path: root/src/vim9compile.c

/* vi:set ts=8 sts=4 sw=4 noet:
 *
 * VIM - Vi IMproved	by Bram Moolenaar
 *
 * Do ":help uganda"  in Vim to read copying and usage conditions.
 * Do ":help credits" in Vim to see a list of people who contributed.
 * See README.txt for an overview of the Vim source code.
 */

/*
 * vim9compile.c: compiling a :def function
 */

#define USING_FLOAT_STUFF
#include "vim.h"

#if defined(FEAT_EVAL) || defined(PROTO)

// When not generating protos this is included in proto.h
#ifdef PROTO
# include "vim9.h"
#endif

// Functions defined with :def are stored in this growarray.
// They are never removed, so that they can be found by index.
// Deleted functions have the df_deleted flag set.
garray_T def_functions = {0, 0, sizeof(dfunc_T), 50, NULL};

static void delete_def_function_contents(dfunc_T *dfunc, int mark_deleted);

/*
 * Lookup variable "name" in the local scope and return it in "lvar".
 * "lvar->lv_from_outer" is incremented accordingly.
 * If "lvar" is NULL only check if the variable can be found.
 * Return FAIL if not found.
 */
    int
lookup_local(char_u *name, size_t len, lvar_T *lvar, cctx_T *cctx)
{
    int	    idx;
    lvar_T  *lvp;

    if (len == 0)
	return FAIL;

    if (((len == 4 && STRNCMP(name, "this", 4) == 0)
		|| (len == 5 && STRNCMP(name, "super", 5) == 0))
	    && cctx->ctx_ufunc != NULL
	    && (cctx->ctx_ufunc->uf_flags & (FC_OBJECT|FC_NEW)))
    {
	int is_super = *name == 's';
	if (is_super)
	{
	    if (name[5] != '.')
	    {
		emsg(_(e_super_must_be_followed_by_dot));
		return FAIL;
	    }
	    if (cctx->ctx_ufunc->uf_class != NULL
		    && cctx->ctx_ufunc->uf_class->class_extends == NULL)
	    {
		emsg(_(e_using_super_not_in_child_class));
		return FAIL;
	    }
	}
	if (lvar != NULL)
	{
	    CLEAR_POINTER(lvar);
	    lvar->lv_loop_depth = -1;
	    lvar->lv_name = (char_u *)(is_super ? "super" : "this");
	    if (cctx->ctx_ufunc->uf_class != NULL)
	    {
		lvar->lv_type = &cctx->ctx_ufunc->uf_class->class_object_type;
		if (is_super)
		{
		    type_T *type = get_type_ptr(cctx->ctx_type_list);

		    if (type != NULL)
		    {
			*type = *lvar->lv_type;
			lvar->lv_type = type;
			type->tt_flags |= TTFLAG_SUPER;
		    }
		}
	    }
	}
	return OK;
    }

    // Find local in current function scope.
    for (idx = 0; idx < cctx->ctx_locals.ga_len; ++idx)
    {
	lvp = ((lvar_T *)cctx->ctx_locals.ga_data) + idx;
	if (lvp->lv_name != NULL
		&& STRNCMP(name, lvp->lv_name, len) == 0
					       && STRLEN(lvp->lv_name) == len)
	{
	    if (lvar != NULL)
	    {
		*lvar = *lvp;
		lvar->lv_from_outer = 0;
		// If the variable was declared inside a loop set
		// lvar->lv_loop_idx and lvar->lv_loop_depth.
		get_loop_var_idx(cctx, idx, lvar);
	    }
	    return OK;
	}
    }

    // Find local in outer function scope.
    if (cctx->ctx_outer != NULL)
    {
	if (lookup_local(name, len, lvar, cctx->ctx_outer) == OK)
	{
	    if (lvar != NULL)
	    {
		cctx->ctx_outer_used = TRUE;
		++lvar->lv_from_outer;
	    }
	    return OK;
	}
    }

    return FAIL;
}

/*
 * Lookup an argument in the current function and an enclosing function.
 * Returns the argument index in "idxp"
 * Returns the argument type in "type"
 * Sets "gen_load_outer" to TRUE if found in outer scope.
 * Returns OK when found, FAIL otherwise.
 */
    int
arg_exists(
	char_u	*name,
	size_t	len,
	int	*idxp,
	type_T	**type,
	int	*gen_load_outer,
	cctx_T	*cctx)
{
    int	    idx;
    char_u  *va_name;

    if (len == 0)
	return FAIL;
    for (idx = 0; idx < cctx->ctx_ufunc->uf_args_visible; ++idx)
    {
	char_u *arg = FUNCARG(cctx->ctx_ufunc, idx);

	if (STRNCMP(name, arg, len) == 0 && arg[len] == NUL)
	{
	    if (idxp != NULL)
	    {
		// Arguments are located above the frame pointer.  One further
		// if there is a vararg argument
		*idxp = idx - (cctx->ctx_ufunc->uf_args.ga_len
							    + STACK_FRAME_SIZE)
			      + (cctx->ctx_ufunc->uf_va_name != NULL ? -1 : 0);

		if (cctx->ctx_ufunc->uf_arg_types != NULL)
		    *type = cctx->ctx_ufunc->uf_arg_types[idx];
		else
		    *type = &t_any;
	    }
	    return OK;
	}
    }

    va_name = cctx->ctx_ufunc->uf_va_name;
    if (va_name != NULL
		    && STRNCMP(name, va_name, len) == 0 && va_name[len] == NUL)
    {
	if (idxp != NULL)
	{
	    // varargs is always the last argument
	    *idxp = -STACK_FRAME_SIZE - 1;
	    *type = cctx->ctx_ufunc->uf_va_type;
	}
	return OK;
    }

    if (cctx->ctx_outer != NULL)
    {
	// Lookup the name for an argument of the outer function.
	if (arg_exists(name, len, idxp, type, gen_load_outer, cctx->ctx_outer)
									 == OK)
	{
	    if (gen_load_outer != NULL)
		++*gen_load_outer;
	    return OK;
	}
    }

    return FAIL;
}

/*
 * Lookup a script-local variable in the current script, possibly defined in a
 * block that contains the function "cctx->ctx_ufunc".
 * "cctx" is NULL at the script level, "cstack" is NULL in a function.
 * If "len" is <= 0 "name" must be NUL terminated.
 * Return NULL when not found.
 */
    static sallvar_T *
find_script_var(char_u *name, size_t len, cctx_T *cctx, cstack_T *cstack)
{
    scriptitem_T    *si = SCRIPT_ITEM(current_sctx.sc_sid);
    hashitem_T	    *hi;
    int		    cc;
    sallvar_T	    *sav;
    ufunc_T	    *ufunc;

    // Find the list of all script variables with the right name.
    if (len > 0)
    {
	cc = name[len];
	name[len] = NUL;
    }
    hi = hash_find(&si->sn_all_vars.dv_hashtab, name);
    if (len > 0)
	name[len] = cc;
    if (HASHITEM_EMPTY(hi))
	return NULL;

    sav = HI2SAV(hi);
    if (sav->sav_block_id == 0)
	// variable defined in the top script scope is always visible
	return sav;

    if (cctx == NULL)
    {
	if (cstack == NULL)
	    return NULL;

	// Not in a function scope, find variable with block ID equal to or
	// smaller than the current block id.  Use "cstack" to go up the block
	// scopes.
	while (sav != NULL)
	{
	    int idx;

	    for (idx = cstack->cs_idx; idx >= 0; --idx)
		if (cstack->cs_block_id[idx] == sav->sav_block_id)
		    break;
	    if (idx >= 0)
		break;
	    sav = sav->sav_next;
	}
	return sav;
    }

    // Go over the variables with this name and find one that was visible
    // from the function.
    ufunc = cctx->ctx_ufunc;
    while (sav != NULL)
    {
	int idx;

	// Go over the blocks that this function was defined in.  If the
	// variable block ID matches it was visible to the function.
	for (idx = 0; idx < ufunc->uf_block_depth; ++idx)
	    if (ufunc->uf_block_ids[idx] == sav->sav_block_id)
		return sav;
	sav = sav->sav_next;
    }

    // Not found, variable was not visible.
    return NULL;
}

/*
 * If "name" can be found in the current script set it's "block_id".
 */
    void
update_script_var_block_id(char_u *name, int block_id)
{
    scriptitem_T    *si = SCRIPT_ITEM(current_sctx.sc_sid);
    hashitem_T	    *hi;
    sallvar_T	    *sav;

    hi = hash_find(&si->sn_all_vars.dv_hashtab, name);
    if (HASHITEM_EMPTY(hi))
	return;
    sav = HI2SAV(hi);
    sav->sav_block_id = block_id;
}

/*
 * Return TRUE if the script context is Vim9 script.
 */
    int
script_is_vim9(void)
{
    return SCRIPT_ITEM(current_sctx.sc_sid)->sn_version == SCRIPT_VERSION_VIM9;
}

/*
 * Lookup a variable (without s: prefix) in the current script.
 * "cctx" is NULL at the script level, "cstack" is NULL in a function.
 * Returns OK or FAIL.
 */
    int
script_var_exists(char_u *name, size_t len, cctx_T *cctx, cstack_T *cstack)
{
    if (current_sctx.sc_sid <= 0)
	return FAIL;
    if (script_is_vim9())
    {
	// Check script variables that were visible where the function was
	// defined.
	if (find_script_var(name, len, cctx, cstack) != NULL)
	    return OK;
    }
    else
    {
	hashtab_T	*ht = &SCRIPT_VARS(current_sctx.sc_sid);
	dictitem_T	*di;
	int		cc;

	// Check script variables that are currently visible
	cc = name[len];
	name[len] = NUL;
	di = find_var_in_ht(ht, 0, name, TRUE);
	name[len] = cc;
	if (di != NULL)
	    return OK;
    }

    return FAIL;
}

/*
 * Returns the index of a class method or class variable with name "name"
 * accessible in the currently compiled function.
 * If "cl_ret" is not NULL set it to the class.
 * Otherwise return -1.
 */
    static int
cctx_class_midx(
    cctx_T  *cctx,
    int	    is_method,
    char_u  *name,
    size_t  len,
    class_T **cl_ret)
{
    if (cctx == NULL || cctx->ctx_ufunc == NULL
	    || cctx->ctx_ufunc->uf_class == NULL
	    || cctx->ctx_ufunc->uf_defclass == NULL)
	return -1;

    // Search for the class method or variable in the class where the calling
    // function is defined.
    class_T *cl = cctx->ctx_ufunc->uf_defclass;
    int m_idx = is_method ? class_method_idx(cl, name, len)
					: class_member_idx(cl, name, len);
    if (m_idx < 0)
    {
	cl = cl->class_extends;
	while (cl != NULL)
	{
	    m_idx = is_method ? class_method_idx(cl, name, len)
					: class_member_idx(cl, name, len);
	    if (m_idx >= 0)
		break;
	    cl = cl->class_extends;
	}
    }

    if (m_idx >= 0)
    {
	if (cl_ret != NULL)
	    *cl_ret = cl;
    }

    return m_idx;
}

/*
 * Returns the index of a class method with name "name" accessible in the
 * currently compiled function.  Returns -1 if not found.  The class where the
 * method is defined is returned in "cl_ret".
 */
    int
cctx_class_method_idx(
    cctx_T  *cctx,
    char_u  *name,
    size_t  len,
    class_T **cl_ret)
{
    return cctx_class_midx(cctx, TRUE, name, len, cl_ret);
}

/*
 * Returns the index of a class variable with name "name" accessible in the
 * currently compiled function.  Returns -1 if not found.  The class where the
 * variable is defined is returned in "cl_ret".
 */
    int
cctx_class_member_idx(
    cctx_T  *cctx,
    char_u  *name,
    size_t  len,
    class_T **cl_ret)
{
    return cctx_class_midx(cctx, FALSE, name, len, cl_ret);
}

/*
 * Return TRUE if "name" is a local variable, argument, script variable or
 * imported.  Also if "name" is "this" and in a class method.
 */
    static int
variable_exists(char_u *name, size_t len, cctx_T *cctx)
{
    return (cctx != NULL
		&& (lookup_local(name, len, NULL, cctx) == OK
		    || arg_exists(name, len, NULL, NULL, NULL, cctx) == OK
		    || (len == 4
			&& cctx->ctx_ufunc != NULL
			&& (cctx->ctx_ufunc->uf_flags & (FC_OBJECT|FC_NEW))
			&& STRNCMP(name, "this", 4) == 0)))
	    || script_var_exists(name, len, cctx, NULL) == OK
	    || cctx_class_member_idx(cctx, name, len, NULL) >= 0
	    || find_imported(name, len, FALSE) != NULL;
}

/*
 * Return TRUE if "name" is a local variable, argument, script variable,
 * imported or function.  Or commands are being skipped, a declaration may have
 * been skipped then.
 */
    static int
item_exists(char_u *name, size_t len, int cmd UNUSED, cctx_T *cctx)
{
    return variable_exists(name, len, cctx);
}

/*
 * Check if "p[len]" is already defined, either in script "import_sid" or in
 * compilation context "cctx".
 * "cctx" is NULL at the script level, "cstack" is NULL in a function.
 * Does not check the global namespace.
 * If "is_arg" is TRUE the error message is for an argument name.
 * Return FAIL and give an error if it defined.
 */
    int
check_defined(
	char_u	    *p,
	size_t	    len,
	cctx_T	    *cctx,
	cstack_T    *cstack,
	int	    is_arg)
{
    int		c = p[len];
    ufunc_T	*ufunc = NULL;

    // underscore argument is OK
    if (len == 1 && *p == '_')
	return OK;

    if (script_var_exists(p, len, cctx, cstack) == OK)
    {
	if (is_arg)
	    semsg(_(e_argument_already_declared_in_script_str), p);
	else
	    semsg(_(e_variable_already_declared_in_script_str), p);
	return FAIL;
    }

    if (cctx_class_member_idx(cctx, p, len, NULL) >= 0)
    {
	if (is_arg)
	    semsg(_(e_argument_already_declared_in_class_str), p);
	else
	    semsg(_(e_variable_already_declared_in_class_str), p);
	return FAIL;
    }

    p[len] = NUL;
    if ((cctx != NULL
		&& (lookup_local(p, len, NULL, cctx) == OK
		    || arg_exists(p, len, NULL, NULL, NULL, cctx) == OK))
	    || find_imported(p, len, FALSE) != NULL
	    || (ufunc = find_func_even_dead(p, 0)) != NULL)
    {
	// A local or script-local function can shadow a global function.
	if (ufunc == NULL || ((ufunc->uf_flags & FC_DEAD) == 0
		    && (!func_is_global(ufunc)
					     || (p[0] == 'g' && p[1] == ':'))))
	{
	    if (is_arg)
		semsg(_(e_argument_name_shadows_existing_variable_str), p);
	    else
		semsg(_(e_name_already_defined_str), p);
	    p[len] = c;
	    return FAIL;
	}
    }
    p[len] = c;
    return OK;
}


/*
 * Return TRUE if "actual" could be "expected" and a runtime typecheck is to be
 * used.  Return FALSE if the types will never match.
 */
    static int
use_typecheck(type_T *actual, type_T *expected)
{
    if (actual->tt_type == VAR_ANY
	    || actual->tt_type == VAR_UNKNOWN
	    || (actual->tt_type == VAR_FUNC
		&& (expected->tt_type == VAR_FUNC
					   || expected->tt_type == VAR_PARTIAL)
		&& (actual->tt_member == &t_any
		    || actual->tt_member == &t_unknown
		    || actual->tt_argcount < 0)
		&& (actual->tt_member == &t_unknown ||
		    (actual->tt_member == &t_void)
					 == (expected->tt_member == &t_void))))
	return TRUE;
    if ((actual->tt_type == VAR_LIST || actual->tt_type == VAR_DICT)
				       && actual->tt_type == expected->tt_type)
	// This takes care of a nested list or dict.
	return use_typecheck(actual->tt_member, expected->tt_member);
    return FALSE;
}

/*
 * Check that
 * - "actual" matches "expected" type or
 * - "actual" is a type that can be "expected" type: add a runtime check; or
 * - return FAIL.
 * If "actual_is_const" is TRUE then the type won't change at runtime, do not
 * generate a TYPECHECK.
 */
    int
need_type_where(
	type_T	*actual,
	type_T	*expected,
	int	number_ok,	// expect VAR_FLOAT but VAR_NUMBER is OK
	int	offset,
	where_T	where,
	cctx_T	*cctx,
	int	silent,
	int	actual_is_const)
{
    int ret;

    if (expected->tt_type != VAR_CLASS && expected->tt_type != VAR_TYPEALIAS)
    {
	if (check_type_is_value(actual) == FAIL)
	    return FAIL;
    }

    if (expected == &t_bool && actual != &t_bool
					&& (actual->tt_flags & TTFLAG_BOOL_OK))
    {
	// Using "0", "1" or the result of an expression with "&&" or "||" as a
	// boolean is OK but requires a conversion.
	generate_2BOOL(cctx, FALSE, offset);
	return OK;
    }

    ret = check_type_maybe(expected, actual, FALSE, where);
    if (ret == OK)
	return OK;

    // If actual a constant a runtime check makes no sense.  If it's
    // null_function it is OK.
    if (actual_is_const && ret == MAYBE && actual == &t_func_unknown)
	return OK;

    // If the actual type can be the expected type add a runtime check.
    if (!actual_is_const && ret == MAYBE && use_typecheck(actual, expected))
    {
	generate_TYPECHECK(cctx, expected, number_ok, offset,
		where.wt_kind == WT_VARIABLE, where.wt_index);
	return OK;
    }

    if (!silent)
	type_mismatch_where(expected, actual, where);
    return FAIL;
}

    int
need_type(
	type_T	*actual,
	type_T	*expected,
	int	number_ok,  // when expected is float number is also OK
	int	offset,
	int	arg_idx,
	cctx_T	*cctx,
	int	silent,
	int	actual_is_const)
{
    where_T where = WHERE_INIT;

    if (arg_idx > 0)
    {
	where.wt_index = arg_idx;
	where.wt_kind = WT_ARGUMENT;
    }
    return need_type_where(actual, expected, number_ok, offset, where,
						cctx, silent, actual_is_const);
}

/*
 * Set type of variable "lvar" to "type".  If the variable is a constant then
 * the type gets TTFLAG_CONST.
 */
    static void
set_var_type(lvar_T *lvar, type_T *type_arg, cctx_T *cctx)
{
    type_T	*type = type_arg;

    if (lvar->lv_const == ASSIGN_CONST && (type->tt_flags & TTFLAG_CONST) == 0)
    {
	if (type->tt_flags & TTFLAG_STATIC)
	    // entry in static_types[] is followed by const type
	    type = type + 1;
	else
	{
	    type = copy_type(type, cctx->ctx_type_list);
	    type->tt_flags |= TTFLAG_CONST;
	}
    }
    lvar->lv_type = type;
}

/*
 * Reserve space for a local variable.
 * "assign" can be ASSIGN_VAR for :var, ASSIGN_CONST for :const and
 * ASSIGN_FINAL for :final.
 * Return the variable or NULL if it failed.
 */
    lvar_T *
reserve_local(
	cctx_T	*cctx,
	char_u	*name,
	size_t	len,
	int	assign,
	type_T	*type)
{
    lvar_T  *lvar;
    dfunc_T *dfunc;

    if (arg_exists(name, len, NULL, NULL, NULL, cctx) == OK)
    {
	emsg_namelen(_(e_str_is_used_as_argument), name, (int)len);
	return NULL;
    }

    if (GA_GROW_FAILS(&cctx->ctx_locals, 1))
	return NULL;
    lvar = ((lvar_T *)cctx->ctx_locals.ga_data) + cctx->ctx_locals.ga_len++;
    CLEAR_POINTER(lvar);

    // Every local variable uses the next entry on the stack.  We could re-use
    // the last ones when leaving a scope, but then variables used in a closure
    // might get overwritten.  To keep things simple do not re-use stack
    // entries.  This is less efficient, but memory is cheap these days.
    dfunc = ((dfunc_T *)def_functions.ga_data) + cctx->ctx_ufunc->uf_dfunc_idx;
    lvar->lv_idx = dfunc->df_var_names.ga_len;

    lvar->lv_name = vim_strnsave(name, len == 0 ? STRLEN(name) : len);
    lvar->lv_const = assign;
    if (type == &t_unknown || type == &t_any)
	// type not known yet, may be inferred from RHS
	lvar->lv_type = type;
    else
	// may use TTFLAG_CONST
	set_var_type(lvar, type, cctx);

    // Remember the name for debugging.
    if (GA_GROW_FAILS(&dfunc->df_var_names, 1))
	return NULL;
    ((char_u **)dfunc->df_var_names.ga_data)[lvar->lv_idx] =
						    vim_strsave(lvar->lv_name);
    ++dfunc->df_var_names.ga_len;

    return lvar;
}

/*
 * If "check_writable" is ASSIGN_CONST give an error if the variable was
 * defined with :final or :const, if "check_writable" is ASSIGN_FINAL give an
 * error if the variable was defined with :const.
 */
    static int
check_item_writable(svar_T *sv, int check_writable, char_u *name)
{
    if ((check_writable == ASSIGN_CONST && sv->sv_const != 0)
	    || (check_writable == ASSIGN_FINAL
					      && sv->sv_const == ASSIGN_CONST))
    {
	semsg(_(e_cannot_change_readonly_variable_str), name);
	return FAIL;
    }
    return OK;
}

/*
 * Find "name" in script-local items of script "sid".
 * Pass "check_writable" to check_item_writable().
 * "cctx" is NULL at the script level, "cstack" is NULL in a function.
 * Returns the index in "sn_var_vals" if found.
 * If found but not in "sn_var_vals" returns -1.
 * If not found or the variable is not writable returns -2.
 */
    int
get_script_item_idx(
	int	    sid,
	char_u	    *name,
	int	    check_writable,
	cctx_T	    *cctx,
	cstack_T    *cstack)
{
    hashtab_T	    *ht;
    dictitem_T	    *di;
    scriptitem_T    *si = SCRIPT_ITEM(sid);
    svar_T	    *sv;
    int		    idx;

    if (!SCRIPT_ID_VALID(sid))
	return -1;
    if (sid == current_sctx.sc_sid)
    {
	sallvar_T *sav = find_script_var(name, 0, cctx, cstack);

	if (sav == NULL)
	    return -2;
	idx = sav->sav_var_vals_idx;
	sv = ((svar_T *)si->sn_var_vals.ga_data) + idx;
	if (check_item_writable(sv, check_writable, name) == FAIL)
	    return -2;
	return idx;
    }

    // First look the name up in the hashtable.
    ht = &SCRIPT_VARS(sid);
    di = find_var_in_ht(ht, 0, name, TRUE);
    if (di == NULL)
    {
	if (si->sn_autoload_prefix != NULL)
	{
	    hashitem_T *hi;

	    // A variable exported from an autoload script is in the global
	    // variables, we can find it in the all_vars table.
	    hi = hash_find(&si->sn_all_vars.dv_hashtab, name);
	    if (!HASHITEM_EMPTY(hi))
		return HI2SAV(hi)->sav_var_vals_idx;
	}
	return -2;
    }

    // Now find the svar_T index in sn_var_vals.
    for (idx = 0; idx < si->sn_var_vals.ga_len; ++idx)
    {
	sv = ((svar_T *)si->sn_var_vals.ga_data) + idx;
	if (sv->sv_tv == &di->di_tv)
	{
	    if (check_item_writable(sv, check_writable, name) == FAIL)
		return -2;
	    return idx;
	}
    }
    return -1;
}

    static imported_T *
find_imported_in_script(char_u *name, size_t len, int sid)
{
    scriptitem_T    *si;
    int		    idx;

    if (!SCRIPT_ID_VALID(sid))
	return NULL;
    si = SCRIPT_ITEM(sid);
    for (idx = 0; idx < si->sn_imports.ga_len; ++idx)
    {
	imported_T *import = ((imported_T *)si->sn_imports.ga_data) + idx;

	if (len == 0 ? STRCMP(name, import->imp_name) == 0
		     : STRLEN(import->imp_name) == len
				  && STRNCMP(name, import->imp_name, len) == 0)
	    return import;
    }
    return NULL;
}

/*
 * Find "name" in imported items of the current script.
 * If "len" is 0 use any length that works.
 * If "load" is TRUE and the script was not loaded yet, load it now.
 */
    imported_T *
find_imported(char_u *name, size_t len, int load)
{
    if (!SCRIPT_ID_VALID(current_sctx.sc_sid))
	return NULL;

    // Skip over "s:" before "s:something" to find the import name.
    int off = name[0] == 's' && name[1] == ':' ? 2 : 0;

    imported_T *ret = find_imported_in_script(name + off, len - off,
							  current_sctx.sc_sid);
    if (ret != NULL && load && (ret->imp_flags & IMP_FLAGS_AUTOLOAD))
    {
	scid_T	actual_sid = 0;
	int	save_emsg_off = emsg_off;

	// "emsg_off" will be set when evaluating an expression silently, but
	// we do want to know about errors in a script.  Also because it then
	// aborts when an error is encountered.
	emsg_off = FALSE;

	// script found before but not loaded yet
	ret->imp_flags &= ~IMP_FLAGS_AUTOLOAD;
	(void)do_source(SCRIPT_ITEM(ret->imp_sid)->sn_name, FALSE,
						       DOSO_NONE, &actual_sid);
	// If the script is a symlink it may be sourced with another name, may
	// need to adjust the script ID for that.
	if (actual_sid != 0)
	    ret->imp_sid = actual_sid;

	emsg_off = save_emsg_off;
    }
    return ret;
}

/*
 * Called when checking for a following operator at "arg".  When the rest of
 * the line is empty or only a comment, peek the next line.  If there is a next
 * line return a pointer to it and set "nextp".
 * Otherwise skip over white space.
 */
    char_u *
may_peek_next_line(cctx_T *cctx, char_u *arg, char_u **nextp)
{
    char_u *p = skipwhite(arg);

    *nextp = NULL;
    if (*p == NUL || (VIM_ISWHITE(*arg) && vim9_comment_start(p)))
    {
	*nextp = peek_next_line_from_context(cctx);
	if (*nextp != NULL)
	    return *nextp;
    }
    return p;
}

/*
 * Return a pointer to the next line that isn't empty or only contains a
 * comment. Skips over white space.
 * Returns NULL if there is none.
 */
    char_u *
peek_next_line_from_context(cctx_T *cctx)
{
    int lnum = cctx->ctx_lnum;

    while (++lnum < cctx->ctx_ufunc->uf_lines.ga_len)
    {
	char_u *line = ((char_u **)cctx->ctx_ufunc->uf_lines.ga_data)[lnum];
	char_u *p;

	// ignore NULLs inserted for continuation lines
	if (line != NULL)
	{
	    p = skipwhite(line);
	    if (vim9_bad_comment(p))
		return NULL;
	    if (*p != NUL && !vim9_comment_start(p))
		return p;
	}
    }
    return NULL;
}

/*
 * Get the next line of the function from "cctx".
 * Skips over empty lines.  Skips over comment lines if "skip_comment" is TRUE.
 * Returns NULL when at the end.
 */
    char_u *
next_line_from_context(cctx_T *cctx, int skip_comment)
{
    char_u	*line;

    do
    {
	++cctx->ctx_lnum;
	if (cctx->ctx_lnum >= cctx->ctx_ufunc->uf_lines.ga_len)
	{
	    line = NULL;
	    break;
	}
	line = ((char_u **)cctx->ctx_ufunc->uf_lines.ga_data)[cctx->ctx_lnum];
	cctx->ctx_line_start = line;
	SOURCING_LNUM = cctx->ctx_lnum + 1;
    } while (line == NULL || *skipwhite(line) == NUL
		     || (skip_comment && vim9_comment_start(skipwhite(line))));
    return line;
}

/*
 * Skip over white space at "whitep" and assign to "*arg".
 * If "*arg" is at the end of the line, advance to the next line.
 * Also when "whitep" points to white space and "*arg" is on a "#".
 * Return FAIL if beyond the last line, "*arg" is unmodified then.
 */
    int
may_get_next_line(char_u *whitep, char_u **arg, cctx_T *cctx)
{
    *arg = skipwhite(whitep);
    if (vim9_bad_comment(*arg))
	return FAIL;
    if (**arg == NUL || (VIM_ISWHITE(*whitep) && vim9_comment_start(*arg)))
    {
	char_u *next = next_line_from_context(cctx, TRUE);

	if (next == NULL)
	    return FAIL;
	*arg = skipwhite(next);
    }
    return OK;
}

/*
 * Idem, and give an error when failed.
 */
    int
may_get_next_line_error(char_u *whitep, char_u **arg, cctx_T *cctx)
{
    if (may_get_next_line(whitep, arg, cctx) == FAIL)
    {
	SOURCING_LNUM = cctx->ctx_lnum + 1;
	emsg(_(e_line_incomplete));
	return FAIL;
    }
    return OK;
}

/*
 * Get a line from the compilation context, compatible with exarg_T getline().
 * Return a pointer to the line in allocated memory.
 * Return NULL for end-of-file or some error.
 */
    static char_u *
exarg_getline(
	int c UNUSED,
	void *cookie,
	int indent UNUSED,
	getline_opt_T options UNUSED)
{
    cctx_T  *cctx = (cctx_T *)cookie;
    char_u  *p;

    for (;;)
    {
	if (cctx->ctx_lnum >= cctx->ctx_ufunc->uf_lines.ga_len - 1)
	    return NULL;
	++cctx->ctx_lnum;
	p = ((char_u **)cctx->ctx_ufunc->uf_lines.ga_data)[cctx->ctx_lnum];
	// Comment lines result in NULL pointers, skip them.
	if (p != NULL)
	    return vim_strsave(p);
    }
}

    void
fill_exarg_from_cctx(exarg_T *eap, cctx_T *cctx)
{
    eap->ea_getline = exarg_getline;
    eap->cookie = cctx;
    eap->skip = cctx->ctx_skip == SKIP_YES;
}

/*
 * Return TRUE if "ufunc" should be compiled, taking into account whether
 * "profile" indicates profiling is to be done.
 */
    int
func_needs_compiling(ufunc_T *ufunc, compiletype_T compile_type)
{
    switch (ufunc->uf_def_status)
    {
	case UF_TO_BE_COMPILED:
	    return TRUE;

	case UF_COMPILED:
	{
	    dfunc_T *dfunc = ((dfunc_T *)def_functions.ga_data)
							 + ufunc->uf_dfunc_idx;

	    switch (compile_type)
	    {
		case CT_PROFILE:
#ifdef FEAT_PROFILE
		    return dfunc->df_instr_prof == NULL;
#endif
		case CT_NONE:
		    return dfunc->df_instr == NULL;
		case CT_DEBUG:
		    return dfunc->df_instr_debug == NULL;
	    }
	}

	case UF_NOT_COMPILED:
	case UF_COMPILE_ERROR:
	case UF_COMPILING:
	    break;
    }
    return FALSE;
}

/*
 * Compile a nested :def command.
 */
    static char_u *
compile_nested_function(exarg_T *eap, cctx_T *cctx, garray_T *lines_to_free)
{
    int		is_global = *eap->arg == 'g' && eap->arg[1] == ':';
    char_u	*name_start = eap->arg;
    char_u	*name_end = to_name_end(eap->arg, TRUE);
    int		off;
    char_u	*func_name;
    char_u	*lambda_name;
    ufunc_T	*ufunc;
    int		r = FAIL;
    compiletype_T   compile_type;
    int		funcref_isn_idx = -1;
    lvar_T	*lvar = NULL;

    if (eap->forceit)
    {
	emsg(_(e_cannot_use_bang_with_nested_def));
	return NULL;
    }

    if (*name_start == '/')
    {
	name_end = skip_regexp(name_start + 1, '/', TRUE);
	if (*name_end == '/')
	    ++name_end;
	set_nextcmd(eap, name_end);
    }
    if (name_end == name_start || *skipwhite(name_end) != '(')
    {
	if (!ends_excmd2(name_start, name_end))
	{
	    if (*skipwhite(name_end) == '.')
		semsg(_(e_cannot_define_dict_func_in_vim9_script_str),
								     eap->cmd);
	    else
		semsg(_(e_invalid_command_str), eap->cmd);
	    return NULL;
	}

	// "def" or "def Name": list functions
	if (generate_DEF(cctx, name_start, name_end - name_start) == FAIL)
	    return NULL;
	return eap->nextcmd == NULL ? (char_u *)"" : eap->nextcmd;
    }

    // Only g:Func() can use a namespace.
    if (name_start[1] == ':' && !is_global)
    {
	semsg(_(e_namespace_not_supported_str), name_start);
	return NULL;
    }
    if (cctx->ctx_skip != SKIP_YES
	    && check_defined(name_start, name_end - name_start, cctx,
							  NULL, FALSE) == FAIL)
	return NULL;
    if (!ASCII_ISUPPER(is_global ? name_start[2] : name_start[0]))
    {
	semsg(_(e_function_name_must_start_with_capital_str), name_start);
	return NULL;
    }

    eap->arg = name_end;
    fill_exarg_from_cctx(eap, cctx);

    eap->forceit = FALSE;
    // We use the special <Lamba>99 name, but it's not really a lambda.
    lambda_name = vim_strsave(get_lambda_name());
    if (lambda_name == NULL)
	return NULL;

    // This may free the current line, make a copy of the name.
    off = is_global ? 2 : 0;
    func_name = vim_strnsave(name_start + off, name_end - name_start - off);
    if (func_name == NULL)
    {
	r = FAIL;
	goto theend;
    }

    // Make sure "KeyTyped" is not set, it may cause indent to be written.
    int save_KeyTyped = KeyTyped;
    KeyTyped = FALSE;

    ufunc = define_function(eap, lambda_name, lines_to_free, 0, NULL, 0);

    KeyTyped = save_KeyTyped;

    if (ufunc == NULL)
    {
	r = eap->skip ? OK : FAIL;
	goto theend;
    }
    if (eap->nextcmd != NULL)
    {
	semsg(_(e_text_found_after_str_str),
	      eap->cmdidx == CMD_def ? "enddef" : "endfunction", eap->nextcmd);
	r = FAIL;
	func_ptr_unref(ufunc);
	goto theend;
    }

    // copy over the block scope IDs before compiling
    if (!is_global && cctx->ctx_ufunc->uf_block_depth > 0)
    {
	int block_depth = cctx->ctx_ufunc->uf_block_depth;

	ufunc->uf_block_ids = ALLOC_MULT(int, block_depth);
	if (ufunc->uf_block_ids != NULL)
	{
	    mch_memmove(ufunc->uf_block_ids, cctx->ctx_ufunc->uf_block_ids,
						    sizeof(int) * block_depth);
	    ufunc->uf_block_depth = block_depth;
	}
    }

    // Define the funcref before compiling, so that it is found by any
    // recursive call.
    if (is_global)
    {
	r = generate_NEWFUNC(cctx, lambda_name, func_name);
	func_name = NULL;
	lambda_name = NULL;
    }
    else
    {
	// Define a local variable for the function reference.
	lvar = reserve_local(cctx, func_name, name_end - name_start,
					    ASSIGN_CONST, ufunc->uf_func_type);
	if (lvar == NULL)
	    goto theend;
	if (generate_FUNCREF(cctx, ufunc, NULL, FALSE, 0, &funcref_isn_idx) == FAIL)
	    goto theend;
	r = generate_STORE(cctx, ISN_STORE, lvar->lv_idx, NULL);
    }

    compile_type = get_compile_type(ufunc);
#ifdef FEAT_PROFILE
    // If the outer function is profiled, also compile the nested function for
    // profiling.
    if (cctx->ctx_compile_type == CT_PROFILE)
	compile_type = CT_PROFILE;
#endif
    if (func_needs_compiling(ufunc, compile_type)
	    && compile_def_function(ufunc, TRUE, compile_type, cctx) == FAIL)
    {
	func_ptr_unref(ufunc);
	if (lvar != NULL)
	    // Now the local variable can't be used.
	    *lvar->lv_name = '/';  // impossible value
	goto theend;
    }

#ifdef FEAT_PROFILE
    // When the outer function is compiled for profiling, the nested function
    // may be called without profiling.  Compile it here in the right context.
    if (compile_type == CT_PROFILE && func_needs_compiling(ufunc, CT_NONE))
	compile_def_function(ufunc, FALSE, CT_NONE, cctx);
#endif

    // If a FUNCREF instruction was generated, set the index after compiling.
    if (funcref_isn_idx != -1 && ufunc->uf_def_status == UF_COMPILED)
    {
	isn_T	*funcref_isn = ((isn_T *)cctx->ctx_instr.ga_data) +
							funcref_isn_idx;
	funcref_isn->isn_arg.funcref.fr_dfunc_idx = ufunc->uf_dfunc_idx;
    }

theend:
    vim_free(lambda_name);
    vim_free(func_name);
    return r == FAIL ? NULL : (char_u *)"";
}

/*
 * Compile one Vim expression {expr} in string "p".
 * "p" points to the opening "{".
 * Return a pointer to the character after "}", NULL for an error.
 */
    char_u *
compile_one_expr_in_str(char_u *p, cctx_T *cctx)
{
    char_u	*block_start;
    char_u	*block_end;

    // Skip the opening {.
    block_start = skipwhite(p + 1);
    block_end = block_start;
    if (*block_start != NUL && skip_expr(&block_end, NULL) == FAIL)
	return NULL;
    block_end = skipwhite(block_end);
    // The block must be closed by a }.
    if (*block_end != '}')
    {
	semsg(_(e_missing_close_curly_str), p);
	return NULL;
    }
    if (compile_expr0(&block_start, cctx) == FAIL)
	return NULL;
    may_generate_2STRING(-1, TOSTRING_INTERPOLATE, cctx);

    return block_end + 1;
}

/*
 * Compile a string "str" (either containing a literal string or a mix of
 * literal strings and Vim expressions of the form `{expr}`).  This is used
 * when compiling a heredoc assignment to a variable or an interpolated string
 * in a Vim9 def function.  Vim9 instructions are generated to push strings,
 * evaluate expressions, concatenate them and create a list of lines.  When
 * "evalstr" is TRUE, Vim expressions in "str" are evaluated.
 */
    int
compile_all_expr_in_str(char_u *str, int evalstr, cctx_T *cctx)
{
    char_u	*p = str;
    char_u	*val;
    int		count = 0;

    if (cctx->ctx_skip == SKIP_YES)
	return OK;

    if (!evalstr || *str == NUL)
    {
	// Literal string, possibly empty.
	val = *str != NUL ? vim_strsave(str) : NULL;
	return generate_PUSHS(cctx, &val);
    }

    // Push all the string pieces to the stack, followed by a ISN_CONCAT.
    while (*p != NUL)
    {
	char_u	*lit_start;
	int	escaped_brace = FALSE;

	// Look for a block start.
	lit_start = p;
	while (*p != '{' && *p != '}' && *p != NUL)
	    ++p;

	if (*p != NUL && *p == p[1])
	{
	    // Escaped brace, unescape and continue.
	    // Include the brace in the literal string.
	    ++p;
	    escaped_brace = TRUE;
	}
	else if (*p == '}')
	{
	    semsg(_(e_stray_closing_curly_str), str);
	    return FAIL;
	}

	// Append the literal part.
	if (p != lit_start)
	{
	    val = vim_strnsave(lit_start, (size_t)(p - lit_start));
	    if (generate_PUSHS(cctx, &val) == FAIL)
		return FAIL;
	    ++count;
	}

	if (*p == NUL)
	    break;

	if (escaped_brace)
	{
	    // Skip the second brace.
	    ++p;
	    continue;
	}

	p = compile_one_expr_in_str(p, cctx);
	if (p == NULL)
	    return FAIL;
	++count;
    }

    // Small optimization, if there's only a single piece skip the ISN_CONCAT.
    if (count > 1)
	return generate_CONCAT(cctx, count);

    return OK;
}

/*
 * Return the length of an assignment operator, or zero if there isn't one.
 */
    int
assignment_len(char_u *p, int *heredoc)
{
    if (*p == '=')
    {
	if (p[1] == '<' && p[2] == '<')
	{
	    *heredoc = TRUE;
	    return 3;
	}
	return 1;
    }
    if (vim_strchr((char_u *)"+-*/%", *p) != NULL && p[1] == '=')
	return 2;
    if (STRNCMP(p, "..=", 3) == 0)
	return 3;
    return 0;
}

/*
 * Generate the load instruction for "name".
 */
    static int
generate_loadvar(cctx_T *cctx, lhs_T *lhs)
{
    char_u	*name = lhs->lhs_name;
    type_T	*type = lhs->lhs_type;
    int		res = OK;

    switch (lhs->lhs_dest)
    {
	case dest_option:
	case dest_func_option:
	    generate_LOAD(cctx, ISN_LOADOPT, 0, name, type);
	    break;
	case dest_global:
	    if (vim_strchr(name, AUTOLOAD_CHAR) == NULL)
	    {
		if (name[2] == NUL)
		    generate_instr_type(cctx, ISN_LOADGDICT, &t_dict_any);
		else
		    generate_LOAD(cctx, ISN_LOADG, 0, name + 2, type);
	    }
	    else
		generate_LOAD(cctx, ISN_LOADAUTO, 0, name, type);
	    break;
	case dest_buffer:
	    generate_LOAD(cctx, ISN_LOADB, 0, name + 2, type);
	    break;
	case dest_window:
	    generate_LOAD(cctx, ISN_LOADW, 0, name + 2, type);
	    break;
	case dest_tab:
	    generate_LOAD(cctx, ISN_LOADT, 0, name + 2, type);
	    break;
	case dest_script:
	case dest_script_v9:
	    res = compile_load_scriptvar(cctx,
				  name + (name[1] == ':' ? 2 : 0), NULL, NULL);
	    break;
	case dest_env:
	    // Include $ in the name here
	    generate_LOAD(cctx, ISN_LOADENV, 0, name, type);
	    break;
	case dest_reg:
	    generate_LOAD(cctx, ISN_LOADREG, name[1], NULL, &t_string);
	    break;
	case dest_vimvar:
	    generate_LOADV(cctx, name + 2);
	    break;
	case dest_local:
	    if (cctx->ctx_skip != SKIP_YES)
	    {
		lvar_T	*lvar = lhs->lhs_lvar;
		if (lvar->lv_from_outer > 0)
		    generate_LOADOUTER(cctx, lvar->lv_idx, lvar->lv_from_outer,
				 lvar->lv_loop_depth, lvar->lv_loop_idx, type);
		else
		    generate_LOAD(cctx, ISN_LOAD, lvar->lv_idx, NULL, type);
	    }
	    break;
	case dest_class_member:
	    generate_CLASSMEMBER(cctx, TRUE, lhs->lhs_class,
						     lhs->lhs_classmember_idx);
	    break;
	case dest_expr:
	    // list or dict value should already be on the stack.
	    break;
    }

    return res;
}

/*
 * Skip over "[expr]" or ".member".
 * Does not check for any errors.
 */
    static char_u *
skip_index(char_u *start)
{
    char_u *p = start;

    if (*p == '[')
    {
	p = skipwhite(p + 1);
	(void)skip_expr(&p, NULL);
	p = skipwhite(p);
	if (*p == ']')
	    return p + 1;
	return p;
    }
    // if (*p == '.')
    return to_name_end(p + 1, TRUE);
}

    void
vim9_declare_error(char_u *name)
{
    char *scope = "";

    switch (*name)
    {
	case 'g': scope = _("global"); break;
	case 'b': scope = _("buffer"); break;
	case 'w': scope = _("window"); break;
	case 't': scope = _("tab"); break;
	case 'v': scope = "v:"; break;
	case '$': semsg(_(e_cannot_declare_an_environment_variable_str), name);
		  return;
	case '&': semsg(_(e_cannot_declare_an_option_str), name);
		  return;
	case '@': semsg(_(e_cannot_declare_a_register_str), name);
		  return;
	default: return;
    }
    semsg(_(e_cannot_declare_a_scope_variable_str), scope, name);
}

/*
 * Return TRUE if "name" is a valid register to use.
 * Return FALSE and give an error message if not.
 */
    static int
valid_dest_reg(int name)
{
    if ((name == '@' || valid_yank_reg(name, FALSE)) && name != '.')
	return TRUE;
    emsg_invreg(name);
    return FAIL;
}

/*
 * For one assignment figure out the type of destination.  Return it in "dest".
 * When not recognized "dest" is not set.
 * For an option "option_scope" is set.
 * For a v:var "vimvaridx" is set.
 * "type" is set to the destination type if known, unchanted otherwise.
 * Return FAIL if an error message was given.
 */
    int
get_var_dest(
	char_u		*name,
	assign_dest_T	*dest,
	cmdidx_T	cmdidx,
	int		*option_scope,
	int		*vimvaridx,
	type_T		**type,
	cctx_T		*cctx)
{
    char_u *p;

    if (*name == '&')
    {
	int		cc;
	long		numval;
	getoption_T	opt_type;
	int		opt_p_flags;

	*dest = dest_option;
	if (cmdidx == CMD_final || cmdidx == CMD_const)
	{
	    emsg(_(e_cannot_lock_option));
	    return FAIL;
	}
	p = name;
	p = find_option_end(&p, option_scope);
	if (p == NULL)
	{
	    // cannot happen?
	    emsg(_(e_unexpected_characters_in_assignment));
	    return FAIL;
	}
	cc = *p;
	*p = NUL;
	opt_type = get_option_value(skip_option_env_lead(name),
				   &numval, NULL, &opt_p_flags, *option_scope);
	*p = cc;
	switch (opt_type)
	{
	    case gov_unknown:
		    semsg(_(e_unknown_option_str), name);
		    return FAIL;
	    case gov_string:
	    case gov_hidden_string:
		    if (opt_p_flags & P_FUNC)
		    {
			// might be a Funcref, check the type later
			*type = &t_any;
			*dest = dest_func_option;
		    }
		    else
		    {
			*type = &t_string;
		    }
		    break;
	    case gov_bool:
	    case gov_hidden_bool:
		    *type = &t_bool;
		    break;
	    case gov_number:
	    case gov_hidden_number:
		    *type = &t_number;
		    break;
	}
    }
    else if (*name == '$')
    {
	*dest = dest_env;
	*type = &t_string;
    }
    else if (*name == '@')
    {
	if (!valid_dest_reg(name[1]))
	    return FAIL;
	*dest = dest_reg;
	*type = name[1] == '#' ? &t_number_or_string : &t_string;
    }
    else if (STRNCMP(name, "g:", 2) == 0)
    {
	*dest = dest_global;
    }
    else if (STRNCMP(name, "b:", 2) == 0)
    {
	*dest = dest_buffer;
    }
    else if (STRNCMP(name, "w:", 2) == 0)
    {
	*dest = dest_window;
    }
    else if (STRNCMP(name, "t:", 2) == 0)
    {
	*dest = dest_tab;
    }
    else if (STRNCMP(name, "v:", 2) == 0)
    {
	typval_T	*vtv;
	int		di_flags;

	*vimvaridx = find_vim_var(name + 2, &di_flags);
	if (*vimvaridx < 0)
	{
	    semsg(_(e_variable_not_found_str), name);
	    return FAIL;
	}
	// We use the current value of "sandbox" here, is that OK?
	if (var_check_ro(di_flags, name, FALSE))
	    return FAIL;
	*dest = dest_vimvar;
	vtv = get_vim_var_tv(*vimvaridx);
	*type = typval2type_vimvar(vtv, cctx->ctx_type_list);
    }
    return OK;
}

    static int
is_decl_command(cmdidx_T cmdidx)
{
    return cmdidx == CMD_let || cmdidx == CMD_var
				 || cmdidx == CMD_final || cmdidx == CMD_const;
}

/*
 * Returns TRUE if the class or object variable in "lhs" is modifiable.
 * "var_start" points to the start of the variable name and "lhs->lhs_varlen"
 * has the total length.  Note that the "lhs" can be nested an object reference
 * (e.g.  a.b.c.d.var).
 */
    static int
lhs_class_member_modifiable(lhs_T *lhs, char_u	*var_start, cctx_T *cctx)
{
    size_t	varlen = lhs->lhs_varlen;
    class_T	*cl = lhs->lhs_type->tt_class;
    int		is_object = lhs->lhs_type->tt_type == VAR_OBJECT;
    char_u	*name = var_start + varlen + 1;
    size_t	namelen = lhs->lhs_end - var_start - varlen - 1;
    ocmember_T	*m;

    m = member_lookup(cl, lhs->lhs_type->tt_type, name, namelen, NULL);
    if (m == NULL)
    {
	member_not_found_msg(cl, lhs->lhs_type->tt_type, name, namelen);
	return FALSE;
    }

    if (IS_ENUM(cl))
    {
	semsg(_(e_enumvalue_str_cannot_be_modified), cl->class_name,
		m->ocm_name);
	return FALSE;
    }

    // If it is private member variable, then accessing it outside the
    // class is not allowed.
    // If it is a read only class variable, then it can be modified
    // only inside the class where it is defined.
    if ((m->ocm_access != VIM_ACCESS_ALL) &&
	    ((is_object && !inside_class(cctx, cl))
	     || (!is_object && cctx->ctx_ufunc->uf_class != cl)))
    {
	char *msg = (m->ocm_access == VIM_ACCESS_PRIVATE)
				? e_cannot_access_protected_variable_str
				: e_variable_is_not_writable_str;
	emsg_var_cl_define(msg, m->ocm_name, 0, cl);
	return FALSE;
    }

    return TRUE;
}

/*
 * Figure out the LHS type and other properties for an assignment or one item
 * of ":unlet" with an index.
 * Returns OK or FAIL.
 */
    int
compile_lhs(
	char_u	    *var_start,
	lhs_T	    *lhs,
	cmdidx_T    cmdidx,
	int	    heredoc,
	int	    has_cmd,	    // "var" before "var_start"
	int	    oplen,
	cctx_T	    *cctx)
{
    char_u	*var_end;
    int		is_decl = is_decl_command(cmdidx);

    CLEAR_POINTER(lhs);
    lhs->lhs_dest = dest_local;
    lhs->lhs_vimvaridx = -1;
    lhs->lhs_scriptvar_idx = -1;
    lhs->lhs_member_idx = -1;

    // "dest_end" is the end of the destination, including "[expr]" or
    // ".name".
    // "var_end" is the end of the variable/option/etc. name.
    lhs->lhs_dest_end = skip_var_one(var_start, FALSE);
    if (*var_start == '@')
    {
	if (!valid_dest_reg(var_start[1]))
	    return FAIL;
	var_end = var_start + 2;
    }
    else
    {
	// skip over the leading "&", "&l:", "&g:" and "$"
	var_end = skip_option_env_lead(var_start);
	var_end = to_name_end(var_end, TRUE);
    }

    // "a: type" is declaring variable "a" with a type, not dict "a:".
    if (is_decl && lhs->lhs_dest_end == var_start + 2
					       && lhs->lhs_dest_end[-1] == ':')
	--lhs->lhs_dest_end;
    if (is_decl && var_end == var_start + 2 && var_end[-1] == ':')
	--var_end;
    lhs->lhs_end = lhs->lhs_dest_end;

    // compute the length of the destination without "[expr]" or ".name"
    lhs->lhs_varlen = var_end - var_start;
    lhs->lhs_varlen_total = lhs->lhs_varlen;
    lhs->lhs_name = vim_strnsave(var_start, lhs->lhs_varlen);
    if (lhs->lhs_name == NULL)
	return FAIL;

    if (lhs->lhs_dest_end > var_start + lhs->lhs_varlen)
	// Something follows after the variable: "var[idx]" or "var.key".
	lhs->lhs_has_index = TRUE;

    if (heredoc)
	lhs->lhs_type = &t_list_string;
    else
	lhs->lhs_type = &t_any;

    if (cctx->ctx_skip != SKIP_YES)
    {
	int	    declare_error = FALSE;

	if (get_var_dest(lhs->lhs_name, &lhs->lhs_dest, cmdidx,
				      &lhs->lhs_opt_flags, &lhs->lhs_vimvaridx,
						 &lhs->lhs_type, cctx) == FAIL)
	    return FAIL;
	if (lhs->lhs_dest != dest_local
				 && cmdidx != CMD_const && cmdidx != CMD_final)
	{
	    // Specific kind of variable recognized.
	    declare_error = is_decl;
	}
	else
	{
	    class_T	*defcl;

	    // No specific kind of variable recognized, just a name.
	    if (check_reserved_name(lhs->lhs_name, lhs->lhs_has_index
						&& *var_end == '.') == FAIL)
		return FAIL;

	    if (lookup_local(var_start, lhs->lhs_varlen,
					     &lhs->lhs_local_lvar, cctx) == OK)
	    {
		lhs->lhs_lvar = &lhs->lhs_local_lvar;
	    }
	    else
	    {
		CLEAR_FIELD(lhs->lhs_arg_lvar);
		if (arg_exists(var_start, lhs->lhs_varlen,
			 &lhs->lhs_arg_lvar.lv_idx, &lhs->lhs_arg_lvar.lv_type,
			    &lhs->lhs_arg_lvar.lv_from_outer, cctx) == OK)
		{
		    if (is_decl)
		    {
			semsg(_(e_str_is_used_as_argument), lhs->lhs_name);
			return FAIL;
		    }
		    lhs->lhs_lvar = &lhs->lhs_arg_lvar;
		}
	    }

	    if (lhs->lhs_lvar != NULL)
	    {
		if (is_decl)
		{
		    // if we come here with what looks like an assignment like
		    // .= but which has been rejected by assignment_len() from
		    // may_compile_assignment give a better error message
		    char_u *p = skipwhite(lhs->lhs_end);
		    if (p[0] == '.' && p[1] == '=')
			emsg(_(e_dot_equal_not_supported_with_script_version_two));
		    else if (p[0] == ':')
			// type specified in a non-var assignment
			semsg(_(e_trailing_characters_str), p);
		    else
			semsg(_(e_variable_already_declared_str), lhs->lhs_name);
		    return FAIL;
		}
	    }
	    else if ((lhs->lhs_classmember_idx = cctx_class_member_idx(
			    cctx, var_start, lhs->lhs_varlen, &defcl)) >= 0)
	    {
		if (cctx->ctx_ufunc->uf_defclass != defcl)
		{
		    // A class variable can be accessed without the class name
		    // only inside a class.
		    semsg(_(e_class_variable_str_accessible_only_inside_class_str),
			    lhs->lhs_name, defcl->class_name);
		    return FAIL;
		}
		if (is_decl)
		{
		    semsg(_(e_variable_already_declared_in_class_str),
								lhs->lhs_name);
		    return FAIL;
		}

		ocmember_T	*m =
			&defcl->class_class_members[lhs->lhs_classmember_idx];
		if (oc_var_check_ro(defcl, m))
		    return FAIL;

		lhs->lhs_dest = dest_class_member;
		// The class variable is defined either in the current class or
		// in one of the parent class in the hierarchy.
		lhs->lhs_class = defcl;
		lhs->lhs_type = oc_member_type_by_idx(defcl, FALSE,
						lhs->lhs_classmember_idx);
	    }
	    else
	    {
		int script_namespace = lhs->lhs_varlen > 1
				       && STRNCMP(var_start, "s:", 2) == 0;
		int script_var = (script_namespace
			? script_var_exists(var_start + 2, lhs->lhs_varlen - 2,
								    cctx, NULL)
			  : script_var_exists(var_start, lhs->lhs_varlen,
							    cctx, NULL)) == OK;
		imported_T  *import =
			      find_imported(var_start, lhs->lhs_varlen, FALSE);

		if (script_namespace || script_var || import != NULL)
		{
		    char_u	*rawname = lhs->lhs_name
					   + (lhs->lhs_name[1] == ':' ? 2 : 0);

		    if (script_namespace && current_script_is_vim9())
		    {
			semsg(_(e_cannot_use_s_colon_in_vim9_script_str),
								    var_start);
			return FAIL;
		    }
		    if (is_decl)
		    {
			if (script_namespace)
			    semsg(_(e_cannot_declare_script_variable_in_function_str),
								lhs->lhs_name);
			else
			    semsg(_(e_variable_already_declared_in_script_str),
								lhs->lhs_name);
			return FAIL;
		    }
		    else if (cctx->ctx_ufunc->uf_script_ctx_version
							 == SCRIPT_VERSION_VIM9
				    && script_namespace
				    && !script_var && import == NULL)
		    {
			semsg(_(e_unknown_variable_str), lhs->lhs_name);
			return FAIL;
		    }

		    lhs->lhs_dest = current_script_is_vim9()
			      ? dest_script_v9 : dest_script;

		    // existing script-local variables should have a type
		    lhs->lhs_scriptvar_sid = current_sctx.sc_sid;
		    if (import != NULL)
		    {
			char_u	*dot = vim_strchr(var_start, '.');
			char_u	*p;

			// for an import the name is what comes after the dot
			if (dot == NULL)
			{
			    semsg(_(e_no_dot_after_imported_name_str),
								    var_start);
			    return FAIL;
			}
			p = skipwhite(dot + 1);
			var_end = to_name_end(p, TRUE);
			if (var_end == p)
			{
			    semsg(_(e_missing_name_after_imported_name_str),
								    var_start);
			    return FAIL;
			}
			vim_free(lhs->lhs_name);
			lhs->lhs_varlen = var_end - p;
			lhs->lhs_name = vim_strnsave(p, lhs->lhs_varlen);
			if (lhs->lhs_name == NULL)
			    return FAIL;
			rawname = lhs->lhs_name;
			lhs->lhs_scriptvar_sid = import->imp_sid;
			// TODO: where do we check this name is exported?

			// Check if something follows: "exp.var[idx]" or
			// "exp.var.key".
			lhs->lhs_has_index = lhs->lhs_dest_end
							  > skipwhite(var_end);
		    }
		    if (SCRIPT_ID_VALID(lhs->lhs_scriptvar_sid))
		    {
			// Check writable only when no index follows.
			lhs->lhs_scriptvar_idx = get_script_item_idx(
					       lhs->lhs_scriptvar_sid, rawname,
			      lhs->lhs_has_index ? ASSIGN_FINAL : ASSIGN_CONST,
								   cctx, NULL);
			if (lhs->lhs_scriptvar_idx >= 0)
			{
			    scriptitem_T *si = SCRIPT_ITEM(
						       lhs->lhs_scriptvar_sid);
			    svar_T	 *sv =
					    ((svar_T *)si->sn_var_vals.ga_data)
						      + lhs->lhs_scriptvar_idx;
			    lhs->lhs_type = sv->sv_type;
			}
		    }
		}
		else if (check_defined(var_start, lhs->lhs_varlen, cctx,
							  NULL, FALSE) == FAIL)
		    return FAIL;
	    }
	}

	if (declare_error)
	{
	    vim9_declare_error(lhs->lhs_name);
	    return FAIL;
	}
    }

    // handle "a:name" as a name, not index "name" in "a"
    if (lhs->lhs_varlen > 1 || var_start[lhs->lhs_varlen] != ':')
	var_end = lhs->lhs_dest_end;

    if (lhs->lhs_dest != dest_option && lhs->lhs_dest != dest_func_option)
    {
	if (is_decl && *skipwhite(var_end) == ':')
	{
	    char_u *p;

	    // parse optional type: "let var: type = expr"
	    if (VIM_ISWHITE(*var_end))
	    {
		semsg(_(e_no_white_space_allowed_before_colon_str), var_end);
		return FAIL;
	    }
	    if (!VIM_ISWHITE(var_end[1]))
	    {
		semsg(_(e_white_space_required_after_str_str), ":", var_end);
		return FAIL;
	    }
	    p = skipwhite(var_end + 1);
	    lhs->lhs_type = parse_type(&p, cctx->ctx_type_list, TRUE);
	    if (lhs->lhs_type == NULL)
		return FAIL;
	    lhs->lhs_has_type = TRUE;
	    lhs->lhs_end = p;
	}
	else if (lhs->lhs_lvar != NULL)
	    lhs->lhs_type = lhs->lhs_lvar->lv_type;
    }

    if (oplen == 3 && !heredoc
		   && lhs->lhs_dest != dest_global
		   && !lhs->lhs_has_index
		   && lhs->lhs_type->tt_type != VAR_STRING
		   && lhs->lhs_type->tt_type != VAR_ANY)
    {
	emsg(_(e_can_only_concatenate_to_string));
	return FAIL;
    }

    if (lhs->lhs_lvar == NULL && lhs->lhs_dest == dest_local
						 && cctx->ctx_skip != SKIP_YES)
    {
	if (oplen > 1 && !heredoc)
	{
	    // +=, /=, etc. require an existing variable
	    semsg(_(e_cannot_use_operator_on_new_variable_str), lhs->lhs_name);
	    return FAIL;
	}
	if (!is_decl || (lhs->lhs_has_index && !has_cmd
						&& cctx->ctx_skip != SKIP_YES))
	{
	    semsg(_(e_unknown_variable_str), lhs->lhs_name);
	    return FAIL;
	}

	// Check the name is valid for a funcref.
	if ((lhs->lhs_type->tt_type == VAR_FUNC
				      || lhs->lhs_type->tt_type == VAR_PARTIAL)
		&& var_wrong_func_name(lhs->lhs_name, TRUE))
	    return FAIL;

	// New local variable.
	int assign = cmdidx == CMD_final ? ASSIGN_FINAL
			     : cmdidx == CMD_const ? ASSIGN_CONST : ASSIGN_VAR;
	lhs->lhs_lvar = reserve_local(cctx, var_start, lhs->lhs_varlen,
							assign, lhs->lhs_type);
	if (lhs->lhs_lvar == NULL)
	    return FAIL;
	lhs->lhs_new_local = TRUE;
    }

    lhs->lhs_member_type = lhs->lhs_type;
    if (lhs->lhs_has_index)
    {
	char_u	*after = var_start + lhs->lhs_varlen;
	char_u	*p;

	// Something follows after the variable: "var[idx]" or "var.key".
	if (is_decl && cctx->ctx_skip != SKIP_YES)
	{
	    if (has_cmd)
		emsg(_(e_cannot_use_index_when_declaring_variable));
	    else
		semsg(_(e_unknown_variable_str), lhs->lhs_name);
	    return FAIL;
	}

	// Now: var_start[lhs->lhs_varlen] is '[' or '.'
	// Only the last index is used below, if there are others
	// before it generate code for the expression.  Thus for
	// "ll[1][2]" the expression is "ll[1]" and "[2]" is the index.
	for (;;)
	{
	    p = skip_index(after);
	    if (*p != '[' && *p != '.')
	    {
		lhs->lhs_varlen_total = p - var_start;
		break;
	    }
	    after = p;
	}
	if (after > var_start + lhs->lhs_varlen)
	{
	    lhs->lhs_varlen = after - var_start;
	    lhs->lhs_dest = dest_expr;
	    // We don't know the type before evaluating the expression,
	    // use "any" until then.
	    lhs->lhs_type = &t_any;
	}

	int use_class = lhs->lhs_type != NULL
			    && (lhs->lhs_type->tt_type == VAR_CLASS
				    || lhs->lhs_type->tt_type == VAR_OBJECT);
	if (lhs->lhs_type == NULL
		|| (use_class ? lhs->lhs_type->tt_class == NULL
		    : lhs->lhs_type->tt_member == NULL))
	{
	    lhs->lhs_member_type = &t_any;
	}
	else if (use_class)
	{
	    // for an object or class member get the type of the member
	    class_T	*cl = lhs->lhs_type->tt_class;
	    int		is_object = lhs->lhs_type->tt_type == VAR_OBJECT;
	    char_u	*name = var_start + lhs->lhs_varlen + 1;
	    size_t	namelen = lhs->lhs_end - var_start - lhs->lhs_varlen - 1;

	    ocmember_T	*m = member_lookup(cl, lhs->lhs_type->tt_type,
					name, namelen, &lhs->lhs_member_idx);
	    if (m == NULL)
	    {
		member_not_found_msg(cl, lhs->lhs_type->tt_type, name, namelen);
		return FAIL;
	    }

	    if (IS_ENUM(cl))
	    {
		if (!inside_class(cctx, cl))
		{
		    semsg(_(e_enumvalue_str_cannot_be_modified),
			    cl->class_name, m->ocm_name);
		    return FALSE;
		}
		if (lhs->lhs_type->tt_type == VAR_OBJECT &&
			lhs->lhs_member_idx < 2)
		{
		    char *msg = lhs->lhs_member_idx == 0 ?
			e_enum_str_name_cannot_be_modified :
			e_enum_str_ordinal_cannot_be_modified;
		    semsg(_(msg), cl->class_name);
		    return FALSE;
		}
	    }

	    // If it is private member variable, then accessing it outside the
	    // class is not allowed.
	    // If it is a read only class variable, then it can be modified
	    // only inside the class where it is defined.
	    if ((m->ocm_access != VIM_ACCESS_ALL) &&
		    ((is_object && !inside_class(cctx, cl))
		     || (!is_object && cctx->ctx_ufunc->uf_class != cl)))
	    {
		char *msg = (m->ocm_access == VIM_ACCESS_PRIVATE)
				    ? e_cannot_access_protected_variable_str
				    : e_variable_is_not_writable_str;
		emsg_var_cl_define(msg, m->ocm_name, 0, cl);
		return FAIL;
	    }

	    if (!IS_CONSTRUCTOR_METHOD(cctx->ctx_ufunc)
						&& oc_var_check_ro(cl, m))
		return FAIL;

	    lhs->lhs_member_type = m->ocm_type;
	}
	else
	    lhs->lhs_member_type = lhs->lhs_type->tt_member;
    }
    return OK;
}

/*
 * Figure out the LHS and check a few errors.
 */
    int
compile_assign_lhs(
	char_u	    *var_start,
	lhs_T	    *lhs,
	cmdidx_T    cmdidx,
	int	    is_decl,
	int	    heredoc,
	int	    has_cmd,	    // "var" before "var_start"
	int	    oplen,
	cctx_T	    *cctx)
{
    if (compile_lhs(var_start, lhs, cmdidx, heredoc, has_cmd, oplen, cctx)
								       == FAIL)
	return FAIL;

    if (!lhs->lhs_has_index && lhs->lhs_lvar == &lhs->lhs_arg_lvar)
    {
	semsg(_(e_cannot_assign_to_argument_str), lhs->lhs_name);
	return FAIL;
    }
    if (!is_decl && lhs->lhs_lvar != NULL
			   && lhs->lhs_lvar->lv_const != ASSIGN_VAR
			   && !lhs->lhs_has_index)
    {
	semsg(_(e_cannot_assign_to_constant_str), lhs->lhs_name);
	return FAIL;
    }
    return OK;
}

/*
 * Return TRUE if "lhs" has a range index: "[expr : expr]".
 */
    static int
has_list_index(char_u *idx_start, cctx_T *cctx)
{
    char_u  *p = idx_start;
    int	    save_skip;

    if (*p != '[')
	return FALSE;

    p = skipwhite(p + 1);
    if (*p == ':')
	return TRUE;

    save_skip = cctx->ctx_skip;
    cctx->ctx_skip = SKIP_YES;
    (void)compile_expr0(&p, cctx);
    cctx->ctx_skip = save_skip;
    return *skipwhite(p) == ':';
}

/*
 * For an assignment with an index, compile the "idx" in "var[idx]" or "key" in
 * "var.key".
 */
    static int
compile_assign_index(
	char_u	*var_start,
	lhs_T	*lhs,
	int	*range,
	cctx_T	*cctx)
{
    size_t	varlen = lhs->lhs_varlen;
    char_u	*p;
    int		r = OK;
    int		need_white_before = TRUE;
    int		empty_second;

    p = var_start + varlen;
    if (*p == '[')
    {
	p = skipwhite(p + 1);
	if (*p == ':')
	{
	    // empty first index, push zero
	    r = generate_PUSHNR(cctx, 0);
	    need_white_before = FALSE;
	}
	else
	    r = compile_expr0(&p, cctx);

	if (r == OK && *skipwhite(p) == ':')
	{
	    // unlet var[idx : idx]
	    // blob[idx : idx] = value
	    *range = TRUE;
	    p = skipwhite(p);
	    empty_second = *skipwhite(p + 1) == ']';
	    if ((need_white_before && !IS_WHITE_OR_NUL(p[-1]))
		    || (!empty_second && !IS_WHITE_OR_NUL(p[1])))
	    {
		semsg(_(e_white_space_required_before_and_after_str_at_str),
								      ":", p);
		return FAIL;
	    }
	    p = skipwhite(p + 1);
	    if (*p == ']')
		// empty second index, push "none"
		r = generate_PUSHSPEC(cctx, VVAL_NONE);
	    else
		r = compile_expr0(&p, cctx);
	}

	if (r == OK && *skipwhite(p) != ']')
	{
	    // this should not happen
	    emsg(_(e_missing_closing_square_brace));
	    r = FAIL;
	}
    }
    else if (lhs->lhs_member_idx >= 0)
    {
	// object member index
	r = generate_PUSHNR(cctx, lhs->lhs_member_idx);
    }
    else // if (*p == '.')
    {
	char_u *key_end = to_name_end(p + 1, TRUE);
	char_u *key = vim_strnsave(p + 1, key_end - p - 1);

	r = generate_PUSHS(cctx, &key);
    }
    return r;
}

/*
 * For a LHS with an index, load the variable to be indexed.
 */
    static int
compile_load_lhs(
	lhs_T	*lhs,
	char_u	*var_start,
	type_T	*rhs_type,
	cctx_T	*cctx)
{
    if (lhs->lhs_dest == dest_expr)
    {
	size_t	    varlen = lhs->lhs_varlen;
	int	    c = var_start[varlen];
	int	    lines_len = cctx->ctx_ufunc->uf_lines.ga_len;
	int	    res;

	// Evaluate "ll[expr]" of "ll[expr][idx]".  End the line with a NUL and
	// limit the lines array length to avoid skipping to a following line.
	var_start[varlen] = NUL;
	cctx->ctx_ufunc->uf_lines.ga_len = cctx->ctx_lnum + 1;
	char_u *p = var_start;
	res = compile_expr0(&p, cctx);
	var_start[varlen] = c;
	cctx->ctx_ufunc->uf_lines.ga_len = lines_len;
	if (res == FAIL || p != var_start + varlen)
	{
	    // this should not happen
	    if (res != FAIL)
		emsg(_(e_missing_closing_square_brace));
	    return FAIL;
	}

	lhs->lhs_type = cctx->ctx_type_stack.ga_len == 0 ? &t_void
						  : get_type_on_stack(cctx, 0);

	if (lhs->lhs_type->tt_type == VAR_OBJECT)
	{
	    // Check whether the object variable is modifiable
	    if (!lhs_class_member_modifiable(lhs, var_start, cctx))
		return FAIL;
	}

	// Now we can properly check the type.  The variable is indexed, thus
	// we need the member type.  For a class or object we don't know the
	// type yet, it depends on what member is used.
	// The top item in the stack is the Dict, followed by the key and then
	// the type of the value.
	vartype_T vartype = lhs->lhs_type->tt_type;
	type_T *member_type = lhs->lhs_type->tt_member;
	if (rhs_type != NULL && member_type != NULL
		&& vartype != VAR_OBJECT && vartype != VAR_CLASS
		&& rhs_type != &t_void
		&& need_type(rhs_type, member_type, FALSE,
					    -3, 0, cctx, FALSE, FALSE) == FAIL)
	    return FAIL;

	return OK;
    }

    return  generate_loadvar(cctx, lhs);
}

/*
 * Produce code for loading "lhs" and also take care of an index.
 * Return OK/FAIL.
 */
    int
compile_load_lhs_with_index(lhs_T *lhs, char_u *var_start, cctx_T *cctx)
{
    if (lhs->lhs_type->tt_type == VAR_OBJECT)
    {
	// "this.value": load "this" object and get the value at index for an
	// object or class member get the type of the member.
	// Also for "obj.value".
	char_u *dot = vim_strchr(var_start, '.');
	if (dot == NULL)
	{
	    semsg(_(e_missing_dot_after_object_str), lhs->lhs_name);
	    return FAIL;
	}

	class_T	*cl = lhs->lhs_type->tt_class;
	type_T	*type = oc_member_type(cl, TRUE, dot + 1,
					  lhs->lhs_end, &lhs->lhs_member_idx);
	if (lhs->lhs_member_idx < 0)
	    return FAIL;

	if (dot - var_start == 4 && STRNCMP(var_start, "this", 4) == 0)
	{
	    // load "this"
	    lvar_T  *lvar = lhs->lhs_lvar;
	    int	    rc;

	    if (lvar->lv_from_outer > 0)
		rc = generate_LOADOUTER(cctx, lvar->lv_idx,
			lvar->lv_from_outer, lvar->lv_loop_depth,
			lvar->lv_loop_idx, type);
	    else
		rc = generate_LOAD(cctx, ISN_LOAD, lvar->lv_idx, NULL, type);

	    if (rc == FAIL)
		return FAIL;
	}
	else
	{
	    // load object variable or argument
	    if (compile_load_lhs(lhs, var_start, lhs->lhs_type, cctx) == FAIL)
		return FAIL;
	}
	if (IS_INTERFACE(cl))
	    return generate_GET_ITF_MEMBER(cctx, cl, lhs->lhs_member_idx, type);
	return generate_GET_OBJ_MEMBER(cctx, lhs->lhs_member_idx, type);
    }
    else if (lhs->lhs_type->tt_type == VAR_CLASS)
    {
	// "<classname>.value": load class variable "classname.value"
	char_u *dot = vim_strchr(var_start, '.');
	if (dot == NULL)
	{
	    check_type_is_value(lhs->lhs_type);
	    return FAIL;
	}

	class_T	*cl = lhs->lhs_type->tt_class;
	ocmember_T *m = class_member_lookup(cl, dot + 1,
						lhs->lhs_end - dot - 1,
						&lhs->lhs_member_idx);
	if (m == NULL)
	    return FAIL;

	return generate_CLASSMEMBER(cctx, TRUE, cl, lhs->lhs_member_idx);
    }

    if (compile_load_lhs(lhs, var_start, NULL, cctx) == FAIL)
	return FAIL;

    if (lhs->lhs_has_index)
    {
	int range = FALSE;

	// Get member from list or dict.  First compile the
	// index value.
	if (compile_assign_index(var_start, lhs, &range, cctx) == FAIL)
	    return FAIL;
	if (range)
	{
	    semsg(_(e_cannot_use_range_with_assignment_operator_str),
								    var_start);
	    return FAIL;
	}

	// Get the member.
	if (compile_member(FALSE, NULL, cctx) == FAIL)
	    return FAIL;
    }
    return OK;
}

/*
 * Assignment to a list or dict member, or ":unlet" for the item, using the
 * information in "lhs".
 * Returns OK or FAIL.
 */
    int
compile_assign_unlet(
	char_u	*var_start,
	lhs_T	*lhs,
	int	is_assign,
	type_T	*rhs_type,
	cctx_T	*cctx)
{
    vartype_T	dest_type;
    int		range = FALSE;

    if (compile_assign_index(var_start, lhs, &range, cctx) == FAIL)
	return FAIL;
    if (is_assign && range
	    && lhs->lhs_type->tt_type != VAR_LIST
	    && lhs->lhs_type != &t_blob
	    && lhs->lhs_type != &t_any)
    {
	semsg(_(e_cannot_use_range_with_assignment_str), var_start);
	return FAIL;
    }

    if (lhs->lhs_type == NULL || lhs->lhs_type == &t_any)
    {
	// Index on variable of unknown type: check at runtime.
	dest_type = VAR_ANY;
    }
    else
    {
	dest_type = lhs->lhs_type->tt_type;
	if (dest_type == VAR_DICT && range)
	{
	    emsg(_(e_cannot_use_range_with_dictionary));
	    return FAIL;
	}
	if (dest_type == VAR_DICT
		&& may_generate_2STRING(-1, TOSTRING_NONE, cctx) == FAIL)
	    return FAIL;
	if (dest_type == VAR_LIST || dest_type == VAR_BLOB)
	{
	    type_T *type;

	    if (range)
	    {
		type = get_type_on_stack(cctx, 1);
		if (need_type(type, &t_number, FALSE,
					    -2, 0, cctx, FALSE, FALSE) == FAIL)
		return FAIL;
	    }
	    type = get_type_on_stack(cctx, 0);
	    if ((dest_type != VAR_BLOB && type->tt_type != VAR_SPECIAL)
		    && need_type(type, &t_number, FALSE,
					    -1, 0, cctx, FALSE, FALSE) == FAIL)
		return FAIL;
	}
    }

    if (cctx->ctx_skip == SKIP_YES)
	return OK;

    // Load the dict, list or object.  On the stack we then have:
    // - value (for assignment, not for :unlet)
    // - index
    // - for [a : b] second index
    // - variable
    if (compile_load_lhs(lhs, var_start, rhs_type, cctx) == FAIL)
	return FAIL;

    if (dest_type == VAR_LIST
	    || dest_type == VAR_DICT
	    || dest_type == VAR_BLOB
	    || dest_type == VAR_CLASS
	    || dest_type == VAR_OBJECT
	    || dest_type == VAR_ANY)
    {
	if (is_assign)
	{
	    if (range)
	    {
		if (generate_instr_drop(cctx, ISN_STORERANGE, 4) == NULL)
		    return FAIL;
	    }
	    else
	    {
		isn_T	*isn = generate_instr_drop(cctx, ISN_STOREINDEX, 3);

		if (isn == NULL)
		    return FAIL;
		isn->isn_arg.storeindex.si_vartype = dest_type;
		isn->isn_arg.storeindex.si_class = NULL;

		if (dest_type == VAR_OBJECT)
		{
		    class_T *cl = lhs->lhs_type->tt_class;

		    if (IS_INTERFACE(cl))
		    {
			// "this.value": load "this" object and get the value
			// at index for an object or class member get the type
			// of the member
			isn->isn_arg.storeindex.si_class = cl;
			++cl->class_refcount;
		    }
		}
	    }
	}
	else if (range)
	{
	    if (generate_instr_drop(cctx, ISN_UNLETRANGE, 3) == NULL)
		return FAIL;
	}
	else
	{
	    if (generate_instr_drop(cctx, ISN_UNLETINDEX, 2) == NULL)
		return FAIL;
	}
    }
    else
    {
	emsg(_(e_indexable_type_required));
	return FAIL;
    }

    return OK;
}

/*
 * Generate an instruction to push the default value for "vartype".
 * if "dest_local" is TRUE then for some types no instruction is generated.
 * "skip_store" is set to TRUE if no PUSH instruction is generated.
 * Returns OK or FAIL.
 */
    static int
push_default_value(
	cctx_T	    *cctx,
	vartype_T   vartype,
	int	    dest_is_local,
	int	    *skip_store)
{
    int r = OK;

    switch (vartype)
    {
	case VAR_BOOL:
	    r = generate_PUSHBOOL(cctx, VVAL_FALSE);
	    break;
	case VAR_FLOAT:
	    r = generate_PUSHF(cctx, 0.0);
	    break;
	case VAR_STRING:
	    r = generate_PUSHS(cctx, NULL);
	    break;
	case VAR_BLOB:
	    r = generate_PUSHBLOB(cctx, blob_alloc());
	    break;
	case VAR_FUNC:
	    r = generate_PUSHFUNC(cctx, NULL, &t_func_void, TRUE);
	    break;
	case VAR_LIST:
	    r = generate_NEWLIST(cctx, 0, FALSE);
	    break;
	case VAR_DICT:
	    r = generate_NEWDICT(cctx, 0, FALSE);
	    break;
	case VAR_JOB:
	    r = generate_PUSHJOB(cctx);
	    break;
	case VAR_CHANNEL:
	    r = generate_PUSHCHANNEL(cctx);
	    break;
	case VAR_OBJECT:
	    r = generate_PUSHOBJ(cctx);
	    break;
	case VAR_NUMBER:
	case VAR_UNKNOWN:
	case VAR_ANY:
	case VAR_PARTIAL:
	case VAR_VOID:
	case VAR_INSTR:
	case VAR_CLASS:
	case VAR_TYPEALIAS:
	case VAR_SPECIAL:  // cannot happen
	    // This is skipped for local variables, they are always
	    // initialized to zero.  But in a "for" or "while" loop
	    // the value may have been changed.
	    if (dest_is_local && !inside_loop_scope(cctx))
		*skip_store = TRUE;
	    else
		r = generate_PUSHNR(cctx, 0);
	    break;
    }
    return r;
}

/*
 * Compile declaration and assignment:
 * "let name"
 * "var name = expr"
 * "final name = expr"
 * "const name = expr"
 * "name = expr"
 * "arg" points to "name".
 * "++arg" and "--arg"
 * Return NULL for an error.
 * Return "arg" if it does not look like a variable list.
 */
    static char_u *
compile_assignment(
	char_u	    *arg_start,
	exarg_T	    *eap,
	cmdidx_T    cmdidx,
	cctx_T	    *cctx)
{
    char_u	*arg = arg_start;
    char_u	*var_start;
    char_u	*p;
    char_u	*end = arg;
    char_u	*ret = NULL;
    int		var_count = 0;
    int		var_idx;
    int		semicolon = 0;
    int		did_generate_slice = FALSE;
    garray_T	*instr = &cctx->ctx_instr;
    int		jump_instr_idx = instr->ga_len;
    char_u	*op;
    int		oplen = 0;
    int		heredoc = FALSE;
    int		incdec = FALSE;
    type_T	*rhs_type = &t_any;
    char_u	*sp;
    int		is_decl = is_decl_command(cmdidx);
    lhs_T	lhs;
    CLEAR_FIELD(lhs);
    long	start_lnum = SOURCING_LNUM;

    int	has_arg_is_set_prefix = STRNCMP(arg, "ifargisset ", 11) == 0;
    if (has_arg_is_set_prefix)
    {
	arg += 11;
	int def_idx = getdigits(&arg);
	arg = skipwhite(arg);

	// Use a JUMP_IF_ARG_NOT_SET instruction to skip if the value was not
	// given and the default value is "v:none".
	int off = STACK_FRAME_SIZE + (cctx->ctx_ufunc->uf_va_name != NULL
								      ? 1 : 0);
	int count = cctx->ctx_ufunc->uf_def_args.ga_len;
	if (generate_JUMP_IF_ARG(cctx, ISN_JUMP_IF_ARG_NOT_SET,
						def_idx - count - off) == FAIL)
	    goto theend;
    }

    // Skip over the "varname" or "[varname, varname]" to get to any "=".
    p = skip_var_list(arg, TRUE, &var_count, &semicolon, TRUE);
    if (p == NULL)
	return *arg == '[' ? arg : NULL;

    if (eap->cmdidx == CMD_increment || eap->cmdidx == CMD_decrement)
    {
	if (VIM_ISWHITE(eap->cmd[2]))
	{
	    semsg(_(e_no_white_space_allowed_after_str_str),
			 eap->cmdidx == CMD_increment ? "++" : "--", eap->cmd);
	    return NULL;
	}
	op = (char_u *)(eap->cmdidx == CMD_increment ? "+=" : "-=");
	oplen = 2;
	incdec = TRUE;
    }
    else
    {
	sp = p;
	p = skipwhite(p);
	op = p;
	oplen = assignment_len(p, &heredoc);

	if (var_count > 0 && oplen == 0)
	    // can be something like "[1, 2]->func()"
	    return arg;

	if (oplen > 0 && (!VIM_ISWHITE(*sp) || !IS_WHITE_OR_NUL(op[oplen])))
	{
	    error_white_both(op, oplen);
	    return NULL;
	}
    }

    if (heredoc)
    {
	list_T	   *l;

	// [let] varname =<< [trim] {end}
	eap->ea_getline = exarg_getline;
	eap->cookie = cctx;
	l = heredoc_get(eap, op + 3, FALSE, TRUE);
	if (l == NULL)
	    return NULL;

	list_free(l);
	p += STRLEN(p);
	end = p;
    }
    else if (var_count > 0)
    {
	char_u *wp;

	// for "[var, var] = expr" evaluate the expression here, loop over the
	// list of variables below.
	// A line break may follow the "=".

	wp = op + oplen;
	if (may_get_next_line_error(wp, &p, cctx) == FAIL)
	    return FAIL;
	if (compile_expr0(&p, cctx) == FAIL)
	    return NULL;
	end = p;

	if (cctx->ctx_skip != SKIP_YES)
	{
	    type_T	*stacktype;
	    int		needed_list_len;
	    int		did_check = FALSE;

	    stacktype = cctx->ctx_type_stack.ga_len == 0 ? &t_void
						  : get_type_on_stack(cctx, 0);
	    if (stacktype->tt_type == VAR_VOID)
	    {
		emsg(_(e_cannot_use_void_value));
		goto theend;
	    }
	    if (need_type(stacktype, &t_list_any, FALSE, -1, 0, cctx,
							 FALSE, FALSE) == FAIL)
		goto theend;
	    // If a constant list was used we can check the length right here.
	    needed_list_len = semicolon ? var_count - 1 : var_count;
	    if (instr->ga_len > 0)
	    {
		isn_T	*isn = ((isn_T *)instr->ga_data) + instr->ga_len - 1;

		if (isn->isn_type == ISN_NEWLIST)
		{
		    did_check = TRUE;
		    if (semicolon ? isn->isn_arg.number < needed_list_len
			    : isn->isn_arg.number != needed_list_len)
		    {
			semsg(_(e_expected_nr_items_but_got_nr),
				    needed_list_len, (int)isn->isn_arg.number);
			goto theend;
		    }
		}
	    }
	    if (!did_check)
		generate_CHECKLEN(cctx, needed_list_len, semicolon);
	    if (stacktype->tt_member != NULL)
		rhs_type = stacktype->tt_member;
	}
    }

    /*
     * Loop over variables in "[var, var] = expr".
     * For "var = expr" and "let var: type" this is done only once.
     */
    if (var_count > 0)
	var_start = skipwhite(arg + 1);  // skip over the "["
    else
	var_start = arg;
    for (var_idx = 0; var_idx == 0 || var_idx < var_count; var_idx++)
    {
	int	instr_count = -1;
	int	save_lnum;
	int	skip_store = FALSE;
	type_T	*inferred_type = NULL;

	if (var_start[0] == '_' && !eval_isnamec(var_start[1]))
	{
	    // Ignore underscore in "[a, _, b] = list".
	    if (var_count > 0)
	    {
		var_start = skipwhite(var_start + 2);
		continue;
	    }
	    emsg(_(e_cannot_use_underscore_here));
	    goto theend;
	}
	vim_free(lhs.lhs_name);

	/*
	 * Figure out the LHS type and other properties.
	 */
	if (compile_assign_lhs(var_start, &lhs, cmdidx,
				is_decl, heredoc, var_start > eap->cmd,
				oplen, cctx) == FAIL)
	    goto theend;
	if (heredoc)
	{
	    SOURCING_LNUM = start_lnum;
	    if (lhs.lhs_has_type
		    && need_type(&t_list_string, lhs.lhs_type, FALSE,
					    -1, 0, cctx, FALSE, FALSE) == FAIL)
		goto theend;
	}
	else
	{
	    if (cctx->ctx_skip == SKIP_YES)
	    {
		if (oplen > 0 && var_count == 0)
		{
		    // skip over the "=" and the expression
		    p = skipwhite(op + oplen);
		    (void)compile_expr0(&p, cctx);
		}
	    }
	    else if (oplen > 0)
	    {
		int	is_const = FALSE;
		char_u	*wp;

		// for "+=", "*=", "..=" etc. first load the current value
		if (*op != '='
			&& compile_load_lhs_with_index(&lhs, var_start,
								 cctx) == FAIL)
		    goto theend;

		// For "var = expr" evaluate the expression.
		if (var_count == 0)
		{
		    int	r;

		    // Compile the expression.
		    instr_count = instr->ga_len;
		    if (incdec)
		    {
			r = generate_PUSHNR(cctx, 1);
		    }
		    else
		    {
			// Temporarily hide the new local variable here, it is
			// not available to this expression.
			if (lhs.lhs_new_local)
			    --cctx->ctx_locals.ga_len;
			wp = op + oplen;
			if (may_get_next_line_error(wp, &p, cctx) == FAIL)
			{
			    if (lhs.lhs_new_local)
				++cctx->ctx_locals.ga_len;
			    goto theend;
			}
			r = compile_expr0_ext(&p, cctx, &is_const);
			if (lhs.lhs_new_local)
			    ++cctx->ctx_locals.ga_len;
		    }
		    if (r == FAIL)
			goto theend;
		}
		else if (semicolon && var_idx == var_count - 1)
		{
		    // For "[var; var] = expr" get the rest of the list
		    did_generate_slice = TRUE;
		    if (generate_SLICE(cctx, var_count - 1) == FAIL)
			goto theend;
		}
		else
		{
		    // For "[var, var] = expr" get the "var_idx" item from the
		    // list.
		    if (generate_GETITEM(cctx, var_idx, *op != '=') == FAIL)
			goto theend;
		}

		rhs_type = cctx->ctx_type_stack.ga_len == 0 ? &t_void
						  : get_type_on_stack(cctx, 0);
		if (check_type_is_value(rhs_type) == FAIL)
		    goto theend;
		if (lhs.lhs_lvar != NULL && (is_decl || !lhs.lhs_has_type))
		{
		    if ((rhs_type->tt_type == VAR_FUNC
				|| rhs_type->tt_type == VAR_PARTIAL)
			    && !lhs.lhs_has_index
			    && var_wrong_func_name(lhs.lhs_name, TRUE))
			goto theend;

		    if (lhs.lhs_new_local && !lhs.lhs_has_type)
		    {
			if (rhs_type->tt_type == VAR_VOID)
			{
			    emsg(_(e_cannot_use_void_value));
			    goto theend;
			}
			else
			{
			    type_T *type;

			    // An empty list or dict has a &t_unknown member,
			    // for a variable that implies &t_any.
			    if (rhs_type == &t_list_empty)
				type = &t_list_any;
			    else if (rhs_type == &t_dict_empty)
				type = &t_dict_any;
			    else if (rhs_type == &t_unknown)
				type = &t_any;
			    else
			    {
				type = rhs_type;
				inferred_type = rhs_type;
			    }
			    set_var_type(lhs.lhs_lvar, type, cctx);
			}
		    }
		    else if (*op == '=')
		    {
			type_T *use_type = lhs.lhs_lvar->lv_type;
			where_T where = WHERE_INIT;

			// Without operator check type here, otherwise below.
			// Use the line number of the assignment.
			SOURCING_LNUM = start_lnum;
			if (var_count > 0)
			{
			    where.wt_index = var_idx + 1;
			    where.wt_kind = WT_VARIABLE;
			}
			// If assigning to a list or dict member, use the
			// member type.  Not for "list[:] =".
			if (lhs.lhs_has_index
				&& !has_list_index(var_start + lhs.lhs_varlen,
									 cctx))
			    use_type = lhs.lhs_member_type;
			if (need_type_where(rhs_type, use_type, FALSE, -1,
					 where, cctx, FALSE, is_const) == FAIL)
			    goto theend;
		    }
		}
		else
		{
		    type_T *lhs_type = lhs.lhs_member_type;

		    // Special case: assigning to @# can use a number or a
		    // string.
		    // Also: can assign a number to a float.
		    if ((lhs_type == &t_number_or_string
				|| lhs_type == &t_float)
			    && rhs_type->tt_type == VAR_NUMBER)
			lhs_type = &t_number;
		    if (*p != '=' && need_type(rhs_type, lhs_type, FALSE,
					    -1, 0, cctx, FALSE, FALSE) == FAIL)
			goto theend;
		}
	    }
	    else if (cmdidx == CMD_final)
	    {
		emsg(_(e_final_requires_a_value));
		goto theend;
	    }
	    else if (cmdidx == CMD_const)
	    {
		emsg(_(e_const_requires_a_value));
		goto theend;
	    }
	    else if (!lhs.lhs_has_type || lhs.lhs_dest == dest_option
					   || lhs.lhs_dest == dest_func_option)
	    {
		emsg(_(e_type_or_initialization_required));
		goto theend;
	    }
	    else
	    {
		// variables are always initialized
		if (GA_GROW_FAILS(instr, 1))
		    goto theend;
		instr_count = instr->ga_len;
		int r = push_default_value(cctx, lhs.lhs_member_type->tt_type,
				      lhs.lhs_dest == dest_local, &skip_store);
		if (r == FAIL)
		    goto theend;
	    }
	    if (var_count == 0)
		end = p;
	}

	// no need to parse more when skipping
	if (cctx->ctx_skip == SKIP_YES)
	    break;

	if (oplen > 0 && *op != '=')
	{
	    type_T	    *expected;
	    type_T	    *stacktype = NULL;

	    if (*op == '.')
	    {
		if (may_generate_2STRING(-1, TOSTRING_NONE, cctx) == FAIL)
		    goto theend;
	    }
	    else
	    {
		expected = lhs.lhs_member_type;
		stacktype = get_type_on_stack(cctx, 0);
		if (
		    // If variable is float operation with number is OK.
		    !(expected == &t_float && (stacktype == &t_number
			    || stacktype == &t_number_bool))
		    && need_type(stacktype, expected, TRUE, -1, 0, cctx,
							 FALSE, FALSE) == FAIL)
		    goto theend;
	    }

	    if (*op == '.')
	    {
		if (generate_CONCAT(cctx, 2) == FAIL)
		    goto theend;
	    }
	    else if (*op == '+')
	    {
		if (generate_add_instr(cctx,
			    operator_type(lhs.lhs_member_type, stacktype),
				       lhs.lhs_member_type, stacktype,
							  EXPR_APPEND) == FAIL)
		    goto theend;
	    }
	    else if (generate_two_op(cctx, op) == FAIL)
		goto theend;
	}

	// Use the line number of the assignment for store instruction.
	save_lnum = cctx->ctx_lnum;
	cctx->ctx_lnum = start_lnum - 1;

	if (lhs.lhs_has_index)
	{
	    // Use the info in "lhs" to store the value at the index in the
	    // list, dict or object.
	    if (compile_assign_unlet(var_start, &lhs, TRUE, rhs_type, cctx)
								       == FAIL)
	    {
		cctx->ctx_lnum = save_lnum;
		goto theend;
	    }
	}
	else
	{
	    if (is_decl && cmdidx == CMD_const && (lhs.lhs_dest == dest_script
					    || lhs.lhs_dest == dest_script_v9
					    || lhs.lhs_dest == dest_global
					    || lhs.lhs_dest == dest_local))
		// ":const var": lock the value, but not referenced variables
		generate_LOCKCONST(cctx);

	    if ((lhs.lhs_type->tt_type == VAR_DICT
					  || lhs.lhs_type->tt_type == VAR_LIST)
		    && lhs.lhs_type->tt_member != NULL
		    && lhs.lhs_type->tt_member != &t_any
		    && lhs.lhs_type->tt_member != &t_unknown)
		// Set the type in the list or dict, so that it can be checked,
		// also in legacy script.
		generate_SETTYPE(cctx, lhs.lhs_type);
	    else if (inferred_type != NULL
		    && (inferred_type->tt_type == VAR_DICT
					|| inferred_type->tt_type == VAR_LIST)
		    && inferred_type->tt_member != NULL
		    && inferred_type->tt_member != &t_unknown
		    && inferred_type->tt_member != &t_any)
		// Set the type in the list or dict, so that it can be checked,
		// also in legacy script.
		generate_SETTYPE(cctx, inferred_type);

	    if (!skip_store && generate_store_lhs(cctx, &lhs,
						 instr_count, is_decl) == FAIL)
	    {
		cctx->ctx_lnum = save_lnum;
		goto theend;
	    }
	}
	cctx->ctx_lnum = save_lnum;

	if (var_idx + 1 < var_count)
	    var_start = skipwhite(lhs.lhs_end + 1);

	if (has_arg_is_set_prefix)
	{
	    // set instruction index in JUMP_IF_ARG_SET to here
	    isn_T *isn = ((isn_T *)instr->ga_data) + jump_instr_idx;
	    isn->isn_arg.jumparg.jump_where = instr->ga_len;
	}
    }

    // For "[var, var] = expr" drop the "expr" value.
    // Also for "[var, var; _] = expr".
    if (var_count > 0 && (!semicolon || !did_generate_slice))
    {
	if (generate_instr_drop(cctx, ISN_DROP, 1) == NULL)
	    goto theend;
    }

    ret = skipwhite(end);

theend:
    vim_free(lhs.lhs_name);
    return ret;
}

/*
 * Check for an assignment at "eap->cmd", compile it if found.
 * Return NOTDONE if there is none, FAIL for failure, OK if done.
 */
    static int
may_compile_assignment(exarg_T *eap, char_u **line, cctx_T *cctx)
{
    char_u  *pskip;
    char_u  *p;

    // Assuming the command starts with a variable or function name,
    // find what follows.
    // Skip over "var.member", "var[idx]" and the like.
    // Also "&opt = val", "$ENV = val" and "@r = val".
    pskip = (*eap->cmd == '&' || *eap->cmd == '$' || *eap->cmd == '@')
						 ? eap->cmd + 1 : eap->cmd;
    p = to_name_end(pskip, TRUE);
    if (p > eap->cmd && *p != NUL)
    {
	char_u *var_end;
	int	oplen;
	int	heredoc;

	if (eap->cmd[0] == '@')
	    var_end = eap->cmd + 2;
	else
	    var_end = find_name_end(pskip, NULL, NULL,
					FNE_CHECK_START | FNE_INCL_BR);
	oplen = assignment_len(skipwhite(var_end), &heredoc);
	if (oplen > 0)
	{
	    size_t len = p - eap->cmd;

	    // Recognize an assignment if we recognize the variable
	    // name:
	    // "&opt = expr"
	    // "$ENV = expr"
	    // "@r = expr"
	    // "g:var = expr"
	    // "g:[key] = expr"
	    // "local = expr"  where "local" is a local var.
	    // "script = expr"  where "script" is a script-local var.
	    // "import = expr"  where "import" is an imported var
	    if (*eap->cmd == '&'
		    || *eap->cmd == '$'
		    || *eap->cmd == '@'
		    || ((len) > 2 && eap->cmd[1] == ':')
		    || STRNCMP(eap->cmd, "g:[", 3) == 0
		    || variable_exists(eap->cmd, len, cctx))
	    {
		*line = compile_assignment(eap->cmd, eap, CMD_SIZE, cctx);
		if (*line == NULL || *line == eap->cmd)
		    return FAIL;
		return OK;
	    }
	}
    }

    // might be "[var, var] = expr" or "ifargisset this.member = expr"
    if (*eap->cmd == '[' || STRNCMP(eap->cmd, "ifargisset ", 11) == 0)
    {
	*line = compile_assignment(eap->cmd, eap, CMD_SIZE, cctx);
	if (*line == NULL)
	    return FAIL;
	if (*line != eap->cmd)
	    return OK;
    }
    return NOTDONE;
}

/*
 * Check if arguments of "ufunc" shadow variables in "cctx".
 * Return OK or FAIL.
 */
    static int
check_args_shadowing(ufunc_T *ufunc, cctx_T *cctx)
{
    int	    i;
    char_u  *arg;
    int	    r = OK;

    // Make sure arguments are not found when compiling a second time.
    ufunc->uf_args_visible = 0;

    // Check for arguments shadowing variables from the context.
    for (i = 0; i < ufunc->uf_args.ga_len; ++i)
    {
	arg = ((char_u **)(ufunc->uf_args.ga_data))[i];
	if (check_defined(arg, STRLEN(arg), cctx, NULL, TRUE) == FAIL)
	{
	    r = FAIL;
	    break;
	}
    }
    ufunc->uf_args_visible = ufunc->uf_args.ga_len;
    return r;
}

#ifdef HAS_MESSAGE_WINDOW
/*
 * Get a count before a command.  Can only be a number.
 * Returns zero if there is no count.
 * Returns -1 if there is something wrong.
 */
    static long
get_cmd_count(char_u *line, exarg_T *eap)
{
    char_u *p;

    // skip over colons and white space
    for (p = line; *p == ':' || VIM_ISWHITE(*p); ++p)
	;
    if (!SAFE_isdigit(*p))
    {
	// The command or modifiers must be following.  Assume a lower case
	// character means there is a modifier.
	if (p < eap->cmd && !vim_islower(*p))
	{
	    emsg(_(e_invalid_range));
	    return -1;
	}
	return 0;
    }
    return atol((char *)p);
}
#endif

/*
 * Get the compilation type that should be used for "ufunc".
 * Keep in sync with INSTRUCTIONS().
 */
    compiletype_T
get_compile_type(ufunc_T *ufunc)
{
    // Update uf_has_breakpoint if needed.
    update_has_breakpoint(ufunc);

    if (debug_break_level > 0 || may_break_in_function(ufunc))
	return CT_DEBUG;
#ifdef FEAT_PROFILE
    if (do_profiling == PROF_YES)
    {
	if (!ufunc->uf_profiling && has_profiling(FALSE, ufunc->uf_name, NULL,
							    &ufunc->uf_hash))
	    func_do_profile(ufunc);
	if (ufunc->uf_profiling)
	    return CT_PROFILE;
    }
#endif
    return CT_NONE;
}


/*
 * Add a function to the list of :def functions.
 * This sets "ufunc->uf_dfunc_idx" but the function isn't compiled yet.
 */
    static int
add_def_function(ufunc_T *ufunc)
{
    dfunc_T *dfunc;

    if (def_functions.ga_len == 0)
    {
	// The first position is not used, so that a zero uf_dfunc_idx means it
	// wasn't set.
	if (GA_GROW_FAILS(&def_functions, 1))
	    return FAIL;
	++def_functions.ga_len;
    }

    // Add the function to "def_functions".
    if (GA_GROW_FAILS(&def_functions, 1))
	return FAIL;
    dfunc = ((dfunc_T *)def_functions.ga_data) + def_functions.ga_len;
    CLEAR_POINTER(dfunc);
    dfunc->df_idx = def_functions.ga_len;
    ufunc->uf_dfunc_idx = dfunc->df_idx;
    dfunc->df_ufunc = ufunc;
    dfunc->df_name = vim_strsave(ufunc->uf_name);
    ga_init2(&dfunc->df_var_names, sizeof(char_u *), 10);
    ++dfunc->df_refcount;
    ++def_functions.ga_len;
    return OK;
}

/*
 * For an object constructor, generate instruction to setup "this" (the first
 * local variable) and to initialize the object variables.
 */
    static int
obj_constructor_prologue(ufunc_T *ufunc, cctx_T *cctx)
{
    generate_CONSTRUCT(cctx, ufunc->uf_class);

    for (int i = 0; i < ufunc->uf_class->class_obj_member_count; ++i)
    {
	ocmember_T *m = &ufunc->uf_class->class_obj_members[i];

	if (i < 2 && IS_ENUM(ufunc->uf_class))
	    // The first two object variables in an enum are the name
	    // and the ordinal.  These are set by the ISN_CONSTRUCT
	    // instruction.  So don't generate instructions to set
	    // these variables.
	    continue;

	if (m->ocm_init != NULL)
	{
	    char_u *expr = m->ocm_init;

	    if (compile_expr0(&expr, cctx) == FAIL)
		return FAIL;

	    if (!ends_excmd2(m->ocm_init, expr))
	    {
		semsg(_(e_trailing_characters_str), expr);
		return FAIL;
	    }

	    type_T	*type = get_type_on_stack(cctx, 0);
	    if (m->ocm_type->tt_type == VAR_ANY
		    && !(m->ocm_flags & OCMFLAG_HAS_TYPE)
		    && type->tt_type != VAR_SPECIAL)
	    {
		// If the member variable type is not yet set, then use
		// the initialization expression type.
		m->ocm_type = type;
	    }
	    else if (m->ocm_type->tt_type != type->tt_type)
	    {
		// The type of the member initialization expression is
		// determined at run time.  Add a runtime type check.
		where_T	where = WHERE_INIT;
		where.wt_kind = WT_MEMBER;
		where.wt_func_name = (char *)m->ocm_name;
		if (need_type_where(type, m->ocm_type, FALSE, -1,
					where, cctx, FALSE, FALSE) == FAIL)
		    return FAIL;
	    }
	}
	else
	    push_default_value(cctx, m->ocm_type->tt_type, FALSE, NULL);

	generate_STORE_THIS(cctx, i);
    }

    return OK;
}

/*
 * For an object method and an constructor, generate instruction to setup
 * "this" (the first local variable).  For a constructor, generate instructions
 * to initialize the object variables.
 */
    static int
obj_method_prologue(ufunc_T *ufunc, cctx_T *cctx)
{
    dfunc_T *dfunc = ((dfunc_T *)def_functions.ga_data) + ufunc->uf_dfunc_idx;

    if (GA_GROW_FAILS(&dfunc->df_var_names, 1))
	return FAIL;

    ((char_u **)dfunc->df_var_names.ga_data)[0] =
						vim_strsave((char_u *)"this");
    ++dfunc->df_var_names.ga_len;

    // In the constructor allocate memory for the object and initialize the
    // object members.
    if (IS_CONSTRUCTOR_METHOD(ufunc))
	return obj_constructor_prologue(ufunc, cctx);

    return OK;
}

/*
 * Produce instructions for the default values of optional arguments.
 */
    static int
compile_def_function_default_args(
    ufunc_T	*ufunc,
    cctx_T	*cctx,
    garray_T	*instr)
{
    int	count = ufunc->uf_def_args.ga_len;
    int	first_def_arg = ufunc->uf_args.ga_len - count;
    int	i;
    int	off = STACK_FRAME_SIZE + (ufunc->uf_va_name != NULL ? 1 : 0);
    int	did_set_arg_type = FALSE;

    // Produce instructions for the default values of optional arguments.
    SOURCING_LNUM = 0;  // line number unknown
    for (i = 0; i < count; ++i)
    {
	char_u *arg = ((char_u **)(ufunc->uf_def_args.ga_data))[i];
	if (STRCMP(arg, "v:none") == 0)
	    // "arg = v:none" means the argument is optional without
	    // setting a value when the argument is missing.
	    continue;

	type_T	*val_type;
	int		arg_idx = first_def_arg + i;
	where_T	where = WHERE_INIT;
	int		jump_instr_idx = instr->ga_len;
	isn_T	*isn;

	// Use a JUMP_IF_ARG_SET instruction to skip if the value was given.
	if (generate_JUMP_IF_ARG(cctx, ISN_JUMP_IF_ARG_SET,
						i - count - off) == FAIL)
	    return FAIL;

	// Make sure later arguments are not found.
	ufunc->uf_args_visible = arg_idx;

	int r = compile_expr0(&arg, cctx);
	if (r == FAIL)
	    return FAIL;

	// If no type specified use the type of the default value.
	// Otherwise check that the default value type matches the
	// specified type.
	val_type = get_type_on_stack(cctx, 0);
	where.wt_index = arg_idx + 1;
	where.wt_kind = WT_ARGUMENT;
	if (ufunc->uf_arg_types[arg_idx] == &t_unknown)
	{
	    did_set_arg_type = TRUE;
	    ufunc->uf_arg_types[arg_idx] = val_type;
	}
	else if (need_type_where(val_type, ufunc->uf_arg_types[arg_idx],
		    FALSE, -1, where, cctx, FALSE, FALSE) == FAIL)
	    return FAIL;

	if (generate_STORE(cctx, ISN_STORE, i - count - off, NULL) == FAIL)
	    return FAIL;

	// set instruction index in JUMP_IF_ARG_SET to here
	isn = ((isn_T *)instr->ga_data) + jump_instr_idx;
	isn->isn_arg.jumparg.jump_where = instr->ga_len;
    }

    if (did_set_arg_type)
	set_function_type(ufunc);

    return OK;
}

/*
 * Compile def function body.  Loop over all the lines in the function and
 * generate instructions.
 */
    static int
compile_def_function_body(
    cctx_T	*cctx,
    int		last_func_lnum,
    int		check_return_type,
    garray_T	*lines_to_free,
    char	**errormsg)
{
    char_u	*line = NULL;
    char_u	*p;
    int		did_emsg_before = did_emsg;
#ifdef FEAT_PROFILE
    int		prof_lnum = -1;
#endif
    int		debug_lnum = -1;

    for (;;)
    {
	exarg_T	    ea;
	int	    starts_with_colon = FALSE;
	char_u	    *cmd;
	cmdmod_T    local_cmdmod;

	// Bail out on the first error to avoid a flood of errors and report
	// the right line number when inside try/catch.
	if (did_emsg_before != did_emsg)
	    return FAIL;

	if (line != NULL && *line == '|')
	    // the line continues after a '|'
	    ++line;
	else if (line != NULL && *skipwhite(line) != NUL
		&& !(*line == '#' && (line == cctx->ctx_line_start
						    || VIM_ISWHITE(line[-1]))))
	{
	    semsg(_(e_trailing_characters_str), line);
	    return FAIL;
	}
	else if (line != NULL && vim9_bad_comment(skipwhite(line)))
	    return FAIL;
	else
	{
	    line = next_line_from_context(cctx, FALSE);
	    if (cctx->ctx_lnum >= last_func_lnum)
	    {
		// beyond the last line
#ifdef FEAT_PROFILE
		if (cctx->ctx_skip != SKIP_YES)
		    may_generate_prof_end(cctx, prof_lnum);
#endif
		break;
	    }
	    // Make a copy, splitting off nextcmd and removing trailing spaces
	    // may change it.
	    if (line != NULL)
	    {
		line = vim_strsave(line);
		if (ga_add_string(lines_to_free, line) == FAIL)
		    return FAIL;
	    }
	}

	CLEAR_FIELD(ea);
	ea.cmdlinep = &line;
	ea.cmd = skipwhite(line);
	ea.skip = cctx->ctx_skip == SKIP_YES;

	if (*ea.cmd == '#')
	{
	    // "#" starts a comment, but "#{" is an error
	    if (vim9_bad_comment(ea.cmd))
		return FAIL;
	    line = (char_u *)"";
	    continue;
	}

#ifdef FEAT_PROFILE
	if (cctx->ctx_compile_type == CT_PROFILE && cctx->ctx_lnum != prof_lnum
						  && cctx->ctx_skip != SKIP_YES)
	{
	    may_generate_prof_end(cctx, prof_lnum);

	    prof_lnum = cctx->ctx_lnum;
	    generate_instr(cctx, ISN_PROF_START);
	}
#endif
	if (cctx->ctx_compile_type == CT_DEBUG && cctx->ctx_lnum != debug_lnum
						  && cctx->ctx_skip != SKIP_YES)
	{
	    debug_lnum = cctx->ctx_lnum;
	    generate_instr_debug(cctx);
	}
	cctx->ctx_prev_lnum = cctx->ctx_lnum + 1;

	// Some things can be recognized by the first character.
	switch (*ea.cmd)
	{
	    case '}':
		{
		    // "}" ends a block scope
		    scopetype_T stype = cctx->ctx_scope == NULL
					  ? NO_SCOPE : cctx->ctx_scope->se_type;

		    if (stype == BLOCK_SCOPE)
		    {
			compile_endblock(cctx);
			line = ea.cmd;
		    }
		    else
		    {
			emsg(_(e_using_rcurly_outside_if_block_scope));
			return FAIL;
		    }
		    if (line != NULL)
			line = skipwhite(ea.cmd + 1);
		    continue;
		}

	    case '{':
		// "{" starts a block scope
		// "{'a': 1}->func() is something else
		if (ends_excmd(*skipwhite(ea.cmd + 1)))
		{
		    line = compile_block(ea.cmd, cctx);
		    continue;
		}
		break;
	}

	/*
	 * COMMAND MODIFIERS
	 */
	cctx->ctx_has_cmdmod = FALSE;
	if (parse_command_modifiers(&ea, errormsg, &local_cmdmod, FALSE)
								       == FAIL)
	    return FAIL;
	generate_cmdmods(cctx, &local_cmdmod);
	undo_cmdmod(&local_cmdmod);

	// Check if there was a colon after the last command modifier or before
	// the current position.
	for (p = ea.cmd; p >= line; --p)
	{
	    if (*p == ':')
		starts_with_colon = TRUE;
	    if (p < ea.cmd && !VIM_ISWHITE(*p))
		break;
	}

	// Skip ":call" to get to the function name, unless using :legacy
	p = ea.cmd;
	if (!(local_cmdmod.cmod_flags & CMOD_LEGACY))
	{
	    if (checkforcmd(&ea.cmd, "call", 3))
	    {
		if (*ea.cmd == '(')
		    // not for "call()"
		    ea.cmd = p;
		else
		    ea.cmd = skipwhite(ea.cmd);
	    }

	    if (!starts_with_colon)
	    {
		int	    assign;

		// Check for assignment after command modifiers.
		assign = may_compile_assignment(&ea, &line, cctx);
		if (assign == OK)
		    goto nextline;
		if (assign == FAIL)
		    return FAIL;
	    }
	}

	/*
	 * COMMAND after range
	 * 'text'->func() should not be confused with 'a mark
	 * 0z1234->func() should not be confused with a zero line number
	 * "++nr" and "--nr" are eval commands
	 * in "$ENV->func()" the "$" is not a range
	 * "123->func()" is a method call
	 */
	cmd = ea.cmd;
	if ((*cmd != '$' || starts_with_colon)
		&& (starts_with_colon
		    || !(*cmd == '\''
			|| (cmd[0] == '0' && cmd[1] == 'z')
			|| (cmd[0] != NUL && cmd[0] == cmd[1]
					    && (*cmd == '+' || *cmd == '-'))
			|| number_method(cmd))))
	{
	    ea.cmd = skip_range(ea.cmd, TRUE, NULL);
	    if (ea.cmd > cmd)
	    {
		if (!starts_with_colon
				   && !(local_cmdmod.cmod_flags & CMOD_LEGACY))
		{
		    semsg(_(e_colon_required_before_range_str), cmd);
		    return FAIL;
		}
		ea.addr_count = 1;
		if (ends_excmd2(line, ea.cmd))
		{
		    // A range without a command: jump to the line.
		    generate_EXEC(cctx, ISN_EXECRANGE,
					      vim_strnsave(cmd, ea.cmd - cmd));
		    line = ea.cmd;
		    goto nextline;
		}
	    }
	}
	p = find_ex_command(&ea, NULL,
		starts_with_colon || (local_cmdmod.cmod_flags & CMOD_LEGACY)
						  ? NULL : item_exists, cctx);

	if (p == NULL)
	{
	    if (cctx->ctx_skip != SKIP_YES)
		semsg(_(e_ambiguous_use_of_user_defined_command_str), ea.cmd);
	    return FAIL;
	}

	// When using ":legacy cmd" always use compile_exec().
	if (local_cmdmod.cmod_flags & CMOD_LEGACY)
	{
	    char_u *start = ea.cmd;

	    switch (ea.cmdidx)
	    {
		case CMD_if:
		case CMD_elseif:
		case CMD_else:
		case CMD_endif:
		case CMD_for:
		case CMD_endfor:
		case CMD_continue:
		case CMD_break:
		case CMD_while:
		case CMD_endwhile:
		case CMD_try:
		case CMD_catch:
		case CMD_finally:
		case CMD_endtry:
			semsg(_(e_cannot_use_legacy_with_command_str), ea.cmd);
			return FAIL;
		default: break;
	    }

	    // ":legacy return expr" needs to be handled differently.
	    if (checkforcmd(&start, "return", 4))
		ea.cmdidx = CMD_return;
	    else
		ea.cmdidx = CMD_legacy;
	}

	if (p == ea.cmd && ea.cmdidx != CMD_SIZE)
	{
	    // "eval" is used for "val->func()" and "var" for "var = val", then
	    // "p" is equal to "ea.cmd" for a valid command.
	    if (ea.cmdidx == CMD_eval || ea.cmdidx == CMD_var)
		;
	    else if (cctx->ctx_skip == SKIP_YES)
	    {
		line += STRLEN(line);
		goto nextline;
	    }
	    else
	    {
		semsg(_(e_command_not_recognized_str), ea.cmd);
		return FAIL;
	    }
	}

	if ((cctx->ctx_had_return || cctx->ctx_had_throw)
		&& ea.cmdidx != CMD_elseif
		&& ea.cmdidx != CMD_else
		&& ea.cmdidx != CMD_endif
		&& ea.cmdidx != CMD_endfor
		&& ea.cmdidx != CMD_endwhile
		&& ea.cmdidx != CMD_catch
		&& ea.cmdidx != CMD_finally
		&& ea.cmdidx != CMD_endtry
		&& !ignore_unreachable_code_for_testing)
	{
	    semsg(_(e_unreachable_code_after_str),
				     cctx->ctx_had_return ? "return" : "throw");
	    return FAIL;
	}
	cctx->ctx_had_throw = FALSE;

	p = skipwhite(p);
	if (ea.cmdidx != CMD_SIZE
			    && ea.cmdidx != CMD_write && ea.cmdidx != CMD_read)
	{
	    if (ea.cmdidx >= 0)
		ea.argt = excmd_get_argt(ea.cmdidx);
	    if ((ea.argt & EX_BANG) && *p == '!')
	    {
		ea.forceit = TRUE;
		p = skipwhite(p + 1);
	    }
	    if ((ea.argt & EX_RANGE) == 0 && ea.addr_count > 0)
	    {
		emsg(_(e_no_range_allowed));
		return FAIL;
	    }
	}

	switch (ea.cmdidx)
	{
	    case CMD_def:
	    case CMD_function:
		    ea.arg = p;
		    line = compile_nested_function(&ea, cctx, lines_to_free);
		    break;

	    case CMD_return:
		    line = compile_return(p, check_return_type,
				 local_cmdmod.cmod_flags & CMOD_LEGACY, cctx);
		    cctx->ctx_had_return = TRUE;
		    break;

	    case CMD_let:
		    emsg(_(e_cannot_use_let_in_vim9_script));
		    break;
	    case CMD_var:
	    case CMD_final:
	    case CMD_const:
	    case CMD_increment:
	    case CMD_decrement:
		    line = compile_assignment(p, &ea, ea.cmdidx, cctx);
		    if (line == p)
		    {
			emsg(_(e_invalid_assignment));
			line = NULL;
		    }
		    break;

	    case CMD_unlet:
	    case CMD_unlockvar:
	    case CMD_lockvar:
		    line = compile_unletlock(p, &ea, cctx);
		    break;

	    case CMD_import:
		    emsg(_(e_import_can_only_be_used_in_script));
		    line = NULL;
		    break;

	    case CMD_if:
		    line = compile_if(p, cctx);
		    break;
	    case CMD_elseif:
		    line = compile_elseif(p, cctx);
		    cctx->ctx_had_return = FALSE;
		    break;
	    case CMD_else:
		    line = compile_else(p, cctx);
		    cctx->ctx_had_return = FALSE;
		    break;
	    case CMD_endif:
		    line = compile_endif(p, cctx);
		    break;

	    case CMD_while:
		    line = compile_while(p, cctx);
		    break;
	    case CMD_endwhile:
		    line = compile_endwhile(p, cctx);
		    cctx->ctx_had_return = FALSE;
		    break;

	    case CMD_for:
		    line = compile_for(p, cctx);
		    break;
	    case CMD_endfor:
		    line = compile_endfor(p, cctx);
		    cctx->ctx_had_return = FALSE;
		    break;
	    case CMD_continue:
		    line = compile_continue(p, cctx);
		    break;
	    case CMD_break:
		    line = compile_break(p, cctx);
		    break;

	    case CMD_try:
		    line = compile_try(p, cctx);
		    break;
	    case CMD_catch:
		    line = compile_catch(p, cctx);
		    cctx->ctx_had_return = FALSE;
		    break;
	    case CMD_finally:
		    line = compile_finally(p, cctx);
		    cctx->ctx_had_return = FALSE;
		    break;
	    case CMD_endtry:
		    line = compile_endtry(p, cctx);
		    break;
	    case CMD_throw:
		    line = compile_throw(p, cctx);
		    cctx->ctx_had_throw = TRUE;
		    break;

	    case CMD_eval:
		    line = compile_eval(p, cctx);
		    break;

	    case CMD_defer:
		    line = compile_defer(p, cctx);
		    break;

#ifdef HAS_MESSAGE_WINDOW
	    case CMD_echowindow:
		    {
			long cmd_count = get_cmd_count(line, &ea);
			if (cmd_count < 0)
			    line = NULL;
			else
			    line = compile_mult_expr(p, ea.cmdidx,
							     cmd_count, cctx);
		    }
		    break;
#endif
	    case CMD_echo:
	    case CMD_echon:
	    case CMD_echoconsole:
	    case CMD_echoerr:
	    case CMD_echomsg:
	    case CMD_execute:
		    line = compile_mult_expr(p, ea.cmdidx, 0, cctx);
		    break;

	    case CMD_put:
		    ea.cmd = cmd;
		    line = compile_put(p, &ea, cctx);
		    break;

	    case CMD_substitute:
		    if (check_global_and_subst(ea.cmd, p) == FAIL)
			return FAIL;
		    if (cctx->ctx_skip == SKIP_YES)
			line = (char_u *)"";
		    else
		    {
			ea.arg = p;
			line = compile_substitute(line, &ea, cctx);
		    }
		    break;

	    case CMD_redir:
		    ea.arg = p;
		    line = compile_redir(line, &ea, cctx);
		    break;

	    case CMD_cexpr:
	    case CMD_lexpr:
	    case CMD_caddexpr:
	    case CMD_laddexpr:
	    case CMD_cgetexpr:
	    case CMD_lgetexpr:
#ifdef FEAT_QUICKFIX
		    ea.arg = p;
		    line = compile_cexpr(line, &ea, cctx);
#else
		    ex_ni(&ea);
		    line = NULL;
#endif
		    break;

	    case CMD_append:
	    case CMD_change:
	    case CMD_insert:
	    case CMD_k:
	    case CMD_t:
	    case CMD_xit:
		    not_in_vim9(&ea);
		    return FAIL;

	    case CMD_SIZE:
		    if (cctx->ctx_skip != SKIP_YES)
		    {
			semsg(_(e_invalid_command_str), ea.cmd);
			return FAIL;
		    }
		    // We don't check for a next command here.
		    line = (char_u *)"";
		    break;

	    case CMD_lua:
	    case CMD_mzscheme:
	    case CMD_perl:
	    case CMD_py3:
	    case CMD_python3:
	    case CMD_python:
	    case CMD_pythonx:
	    case CMD_ruby:
	    case CMD_tcl:
		    ea.arg = p;
		    if (vim_strchr(line, '\n') == NULL)
			line = compile_exec(line, &ea, cctx);
		    else
			// heredoc lines have been concatenated with NL
			// characters in get_function_body()
			line = compile_script(line, cctx);
		    break;

	    case CMD_vim9script:
		    if (cctx->ctx_skip != SKIP_YES)
		    {
			emsg(_(e_vim9script_can_only_be_used_in_script));
			return FAIL;
		    }
		    line = (char_u *)"";
		    break;

	    case CMD_class:
		    emsg(_(e_class_can_only_be_used_in_script));
		    return FAIL;

	    case CMD_type:
		    emsg(_(e_type_can_only_be_used_in_script));
		    return FAIL;

	    case CMD_global:
		    if (check_global_and_subst(ea.cmd, p) == FAIL)
			return FAIL;
		    // FALLTHROUGH
	    default:
		    // Not recognized, execute with do_cmdline_cmd().
		    ea.arg = p;
		    line = compile_exec(line, &ea, cctx);
		    break;
	}
nextline:
	if (line == NULL)
	    return FAIL;
	line = skipwhite(line);

	// Undo any command modifiers.
	generate_undo_cmdmods(cctx);

	if (cctx->ctx_type_stack.ga_len < 0)
	{
	    iemsg("Type stack underflow");
	    return FAIL;
	}
    } // END of the loop over all the function body lines.

    return OK;
}

/*
 * After ex_function() has collected all the function lines: parse and compile
 * the lines into instructions.
 * Adds the function to "def_functions".
 * When "check_return_type" is set then set ufunc->uf_ret_type to the type of
 * the return statement (used for lambda).  When uf_ret_type is already set
 * then check that it matches.
 * When "profiling" is true add ISN_PROF_START instructions.
 * "outer_cctx" is set for a nested function.
 * This can be used recursively through compile_lambda(), which may reallocate
 * "def_functions".
 * Returns OK or FAIL.
 */
    int
compile_def_function(
	ufunc_T		*ufunc,
	int		check_return_type,
	compiletype_T   compile_type,
	cctx_T		*outer_cctx)
{
    garray_T	lines_to_free;
    char	*errormsg = NULL;	// error message
    cctx_T	cctx;
    garray_T	*instr;
    int		did_emsg_before = did_emsg;
    int		did_emsg_silent_before = did_emsg_silent;
    int		ret = FAIL;
    sctx_T	save_current_sctx = current_sctx;
    int		save_estack_compiling = estack_compiling;
    int		save_cmod_flags = cmdmod.cmod_flags;
    int		do_estack_push;
    int		new_def_function = FALSE;

    // allocated lines are freed at the end
    ga_init2(&lines_to_free, sizeof(char_u *), 50);

    // When using a function that was compiled before: Free old instructions.
    // The index is reused.  Otherwise add a new entry in "def_functions".
    if (ufunc->uf_dfunc_idx > 0)
    {
	dfunc_T *dfunc = ((dfunc_T *)def_functions.ga_data)
							 + ufunc->uf_dfunc_idx;
	isn_T	*instr_dest = NULL;

	switch (compile_type)
	{
	    case CT_PROFILE:
#ifdef FEAT_PROFILE
			    instr_dest = dfunc->df_instr_prof; break;
#endif
	    case CT_NONE:   instr_dest = dfunc->df_instr; break;
	    case CT_DEBUG:  instr_dest = dfunc->df_instr_debug; break;
	}
	if (instr_dest != NULL)
	    // Was compiled in this mode before: Free old instructions.
	    delete_def_function_contents(dfunc, FALSE);
	ga_clear_strings(&dfunc->df_var_names);
	dfunc->df_defer_var_idx = 0;
    }
    else
    {
	if (add_def_function(ufunc) == FAIL)
	    return FAIL;
	new_def_function = TRUE;
    }

    if ((ufunc->uf_flags & FC_CLOSURE) && outer_cctx == NULL)
    {
	semsg(_(e_compiling_closure_without_context_str),
						   printable_func_name(ufunc));
	return FAIL;
    }

    ufunc->uf_def_status = UF_COMPILING;

    CLEAR_FIELD(cctx);

    cctx.ctx_compile_type = compile_type;
    cctx.ctx_ufunc = ufunc;
    cctx.ctx_lnum = -1;
    cctx.ctx_outer = outer_cctx;
    ga_init2(&cctx.ctx_locals, sizeof(lvar_T), 10);
    // Each entry on the type stack consists of two type pointers.
    ga_init2(&cctx.ctx_type_stack, sizeof(type2_T), 50);
    cctx.ctx_type_list = &ufunc->uf_type_list;
    ga_init2(&cctx.ctx_instr, sizeof(isn_T), 50);
    instr = &cctx.ctx_instr;

    // Set the context to the function, it may be compiled when called from
    // another script.  Set the script version to the most modern one.
    // The line number will be set in next_line_from_context().
    current_sctx = ufunc->uf_script_ctx;
    current_sctx.sc_version = SCRIPT_VERSION_VIM9;

    // Don't use the flag from ":legacy" here.
    cmdmod.cmod_flags &= ~CMOD_LEGACY;

    // Make sure error messages are OK.
    do_estack_push = !estack_top_is_ufunc(ufunc, 1);
    if (do_estack_push)
	estack_push_ufunc(ufunc, 1);
    estack_compiling = TRUE;

    if (check_args_shadowing(ufunc, &cctx) == FAIL)
	goto erret;

    // For an object method and a constructor generate instructions to
    // initialize "this" and the object variables.
    if (ufunc->uf_flags & (FC_OBJECT|FC_NEW))
	if (obj_method_prologue(ufunc, &cctx) == FAIL)
	    goto erret;

    if (ufunc->uf_def_args.ga_len > 0)
	if (compile_def_function_default_args(ufunc, &cctx, instr) == FAIL)
	    goto erret;
    ufunc->uf_args_visible = ufunc->uf_args.ga_len;

    // Compiling a function in an interface is done to get the function type.
    // No code is actually compiled.
    if (ufunc->uf_class != NULL && IS_INTERFACE(ufunc->uf_class))
    {
	ufunc->uf_def_status = UF_NOT_COMPILED;
	ret = OK;
	goto erret;
    }

    // compile the function body
    if (compile_def_function_body(&cctx, ufunc->uf_lines.ga_len,
		check_return_type, &lines_to_free, &errormsg) == FAIL)
	goto erret;

    if (cctx.ctx_scope != NULL)
    {
	if (cctx.ctx_scope->se_type == IF_SCOPE)
	    emsg(_(e_missing_endif));
	else if (cctx.ctx_scope->se_type == WHILE_SCOPE)
	    emsg(_(e_missing_endwhile));
	else if (cctx.ctx_scope->se_type == FOR_SCOPE)
	    emsg(_(e_missing_endfor));
	else
	    emsg(_(e_missing_rcurly));
	goto erret;
    }

    // TODO: if a function ends in "throw" but there was a return elsewhere we
    // should not assume the return type is "void".
    if (!cctx.ctx_had_return && !cctx.ctx_had_throw)
    {
	if (ufunc->uf_ret_type->tt_type == VAR_UNKNOWN)
	    ufunc->uf_ret_type = &t_void;
	else if (ufunc->uf_ret_type->tt_type != VAR_VOID
		&& !IS_CONSTRUCTOR_METHOD(ufunc))
	{
	    emsg(_(e_missing_return_statement));
	    goto erret;
	}

	// Return void if there is no return at the end.
	// For a constructor return the object.
	if (IS_CONSTRUCTOR_METHOD(ufunc))
	{
	    generate_instr(&cctx, ISN_RETURN_OBJECT);
	    ufunc->uf_ret_type = &ufunc->uf_class->class_object_type;
	}
	else
	    generate_instr(&cctx, ISN_RETURN_VOID);
    }

    // When compiled with ":silent!" and there was an error don't consider the
    // function compiled.
    if (emsg_silent == 0 || did_emsg_silent == did_emsg_silent_before)
    {
	dfunc_T	*dfunc = ((dfunc_T *)def_functions.ga_data)
							 + ufunc->uf_dfunc_idx;
	dfunc->df_deleted = FALSE;
	dfunc->df_script_seq = current_sctx.sc_seq;
#ifdef FEAT_PROFILE
	if (cctx.ctx_compile_type == CT_PROFILE)
	{
	    dfunc->df_instr_prof = instr->ga_data;
	    dfunc->df_instr_prof_count = instr->ga_len;
	}
	else
#endif
	if (cctx.ctx_compile_type == CT_DEBUG)
	{
	    dfunc->df_instr_debug = instr->ga_data;
	    dfunc->df_instr_debug_count = instr->ga_len;
	}
	else
	{
	    dfunc->df_instr = instr->ga_data;
	    dfunc->df_instr_count = instr->ga_len;
	}
	dfunc->df_varcount = dfunc->df_var_names.ga_len;
	dfunc->df_has_closure = cctx.ctx_has_closure;

	if (cctx.ctx_outer_used)
	{
	    ufunc->uf_flags |= FC_CLOSURE;
	    if (outer_cctx != NULL)
		++outer_cctx->ctx_closure_count;
	}

	ufunc->uf_def_status = UF_COMPILED;
    }

    ret = OK;

erret:
    if (ufunc->uf_def_status == UF_COMPILING)
    {
	dfunc_T	*dfunc = ((dfunc_T *)def_functions.ga_data)
							 + ufunc->uf_dfunc_idx;

	// Compiling aborted, free the generated instructions.
	clear_instr_ga(instr);
	VIM_CLEAR(dfunc->df_name);
	ga_clear_strings(&dfunc->df_var_names);

	// If using the last entry in the table and it was added above, we
	// might as well remove it.
	if (!dfunc->df_deleted && new_def_function
			    && ufunc->uf_dfunc_idx == def_functions.ga_len - 1)
	{
	    --def_functions.ga_len;
	    ufunc->uf_dfunc_idx = 0;
	}
	ufunc->uf_def_status = UF_COMPILE_ERROR;

	while (cctx.ctx_scope != NULL)
	    drop_scope(&cctx);

	if (errormsg != NULL)
	    emsg(errormsg);
	else if (did_emsg == did_emsg_before)
	    emsg(_(e_compiling_def_function_failed));
    }

    if (cctx.ctx_redir_lhs.lhs_name != NULL)
    {
	if (ret == OK)
	{
	    emsg(_(e_missing_redir_end));
	    ret = FAIL;
	}
	vim_free(cctx.ctx_redir_lhs.lhs_name);
	vim_free(cctx.ctx_redir_lhs.lhs_whole);
    }

    current_sctx = save_current_sctx;
    estack_compiling = save_estack_compiling;
    cmdmod.cmod_flags =	save_cmod_flags;
    if (do_estack_push)
	estack_pop();

    ga_clear_strings(&lines_to_free);
    free_locals(&cctx);
    ga_clear(&cctx.ctx_type_stack);
    return ret;
}

    void
set_function_type(ufunc_T *ufunc)
{
    int varargs = ufunc->uf_va_name != NULL;
    int argcount = ufunc->uf_args.ga_len;

    // Create a type for the function, with the return type and any
    // argument types.
    // A vararg is included in uf_args.ga_len but not in uf_arg_types.
    // The type is included in "tt_args".
    if (argcount > 0 || varargs)
    {
	if (ufunc->uf_type_list.ga_itemsize == 0)
	    ga_init2(&ufunc->uf_type_list, sizeof(type_T *), 10);
	ufunc->uf_func_type = alloc_func_type(ufunc->uf_ret_type,
					   argcount, &ufunc->uf_type_list);
	// Add argument types to the function type.
	if (func_type_add_arg_types(ufunc->uf_func_type,
				    argcount + varargs,
				    &ufunc->uf_type_list) == FAIL)
	    return;
	ufunc->uf_func_type->tt_argcount = argcount + varargs;
	ufunc->uf_func_type->tt_min_argcount =
				      argcount - ufunc->uf_def_args.ga_len;
	if (ufunc->uf_arg_types == NULL)
	{
	    int i;

	    // lambda does not have argument types.
	    for (i = 0; i < argcount; ++i)
		ufunc->uf_func_type->tt_args[i] = &t_any;
	}
	else
	    mch_memmove(ufunc->uf_func_type->tt_args,
			 ufunc->uf_arg_types, sizeof(type_T *) * argcount);
	if (varargs)
	{
	    ufunc->uf_func_type->tt_args[argcount] =
		   ufunc->uf_va_type == NULL ? &t_list_any : ufunc->uf_va_type;
	    ufunc->uf_func_type->tt_flags = TTFLAG_VARARGS;
	}
    }
    else
	// No arguments, can use a predefined type.
	ufunc->uf_func_type = get_func_type(ufunc->uf_ret_type,
					   argcount, &ufunc->uf_type_list);
}

/*
 * Free all instructions for "dfunc" except df_name.
 */
    static void
delete_def_function_contents(dfunc_T *dfunc, int mark_deleted)
{
    int idx;

    // In same cases the instructions may refer to a class in which the
    // function is defined and unreferencing the class may call back here
    // recursively.  Set the df_delete_busy to avoid problems.
    if (dfunc->df_delete_busy)
	return;
    dfunc->df_delete_busy = TRUE;

    ga_clear(&dfunc->df_def_args_isn);
    ga_clear_strings(&dfunc->df_var_names);

    if (dfunc->df_instr != NULL)
    {
	for (idx = 0; idx < dfunc->df_instr_count; ++idx)
	    delete_instr(dfunc->df_instr + idx);
	VIM_CLEAR(dfunc->df_instr);
    }
    if (dfunc->df_instr_debug != NULL)
    {
	for (idx = 0; idx < dfunc->df_instr_debug_count; ++idx)
	    delete_instr(dfunc->df_instr_debug + idx);
	VIM_CLEAR(dfunc->df_instr_debug);
    }
#ifdef FEAT_PROFILE
    if (dfunc->df_instr_prof != NULL)
    {
	for (idx = 0; idx < dfunc->df_instr_prof_count; ++idx)
	    delete_instr(dfunc->df_instr_prof + idx);
	VIM_CLEAR(dfunc->df_instr_prof);
    }
#endif

    if (mark_deleted)
	dfunc->df_deleted = TRUE;
    if (dfunc->df_ufunc != NULL)
	dfunc->df_ufunc->uf_def_status = UF_NOT_COMPILED;

    dfunc->df_delete_busy = FALSE;
}

/*
 * When a user function is deleted, clear the contents of any associated def
 * function, unless another user function still uses it.
 * The position in def_functions can be re-used.
 */
    void
unlink_def_function(ufunc_T *ufunc)
{
    if (ufunc->uf_dfunc_idx <= 0)
	return;

    dfunc_T *dfunc = ((dfunc_T *)def_functions.ga_data)
	+ ufunc->uf_dfunc_idx;

    if (--dfunc->df_refcount <= 0)
	delete_def_function_contents(dfunc, TRUE);
    ufunc->uf_def_status = UF_NOT_COMPILED;
    ufunc->uf_dfunc_idx = 0;
    if (dfunc->df_ufunc == ufunc)
	dfunc->df_ufunc = NULL;
}

/*
 * Used when a user function refers to an existing dfunc.
 */
    void
link_def_function(ufunc_T *ufunc)
{
    if (ufunc->uf_dfunc_idx <= 0)
	return;

    dfunc_T *dfunc = ((dfunc_T *)def_functions.ga_data)
	+ ufunc->uf_dfunc_idx;

    ++dfunc->df_refcount;
}

#if defined(EXITFREE) || defined(PROTO)
/*
 * Free all functions defined with ":def".
 */
    void
free_def_functions(void)
{
    int idx;

    for (idx = 0; idx < def_functions.ga_len; ++idx)
    {
	dfunc_T *dfunc = ((dfunc_T *)def_functions.ga_data) + idx;

	delete_def_function_contents(dfunc, TRUE);
	vim_free(dfunc->df_name);
    }

    ga_clear(&def_functions);
}
#endif


#endif // FEAT_EVAL