Adding upstream version 3.6.upstream/3.6upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 369 insertions, 0 deletions

diff --git a/lib/verify.h b/lib/verify.h
new file mode 100644
index 0000000..c700243
--- /dev/null
+++ b/lib/verify.h
@@ -0,0 +1,369 @@
+/* Compile-time assert-like macros.
+
+   Copyright (C) 2005-2006, 2009-2023 Free Software Foundation, Inc.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+/* Written by Paul Eggert, Bruno Haible, and Jim Meyering.  */
+
+#ifndef _GL_VERIFY_H
+#define _GL_VERIFY_H
+
+
+/* Define _GL_HAVE__STATIC_ASSERT to 1 if _Static_assert (R, DIAGNOSTIC)
+   works as per C11.  This is supported by GCC 4.6.0+ and by clang 4+.
+
+   Define _GL_HAVE__STATIC_ASSERT1 to 1 if _Static_assert (R) works as
+   per C23.  This is supported by GCC 9.1+.
+
+   Support compilers claiming conformance to the relevant standard,
+   and also support GCC when not pedantic.  If we were willing to slow
+   'configure' down we could also use it with other compilers, but
+   since this affects only the quality of diagnostics, why bother?  */
+#ifndef __cplusplus
+# if (201112 <= __STDC_VERSION__ \
+      || (!defined __STRICT_ANSI__ \
+          && (4 < __GNUC__ + (6 <= __GNUC_MINOR__) || 5 <= __clang_major__)))
+#  define _GL_HAVE__STATIC_ASSERT 1
+# endif
+# if (202311 <= __STDC_VERSION__ \
+      || (!defined __STRICT_ANSI__ && 9 <= __GNUC__))
+#  define _GL_HAVE__STATIC_ASSERT1 1
+# endif
+#endif
+
+/* FreeBSD 9.1 <sys/cdefs.h>, included by <stddef.h> and lots of other
+   system headers, defines a conflicting _Static_assert that is no
+   better than ours; override it.  */
+#ifndef _GL_HAVE__STATIC_ASSERT
+# include <stddef.h>
+# undef _Static_assert
+#endif
+
+/* Each of these macros verifies that its argument R is nonzero.  To
+   be portable, R should be an integer constant expression.  Unlike
+   assert (R), there is no run-time overhead.
+
+   If _Static_assert works, verify (R) uses it directly.  Similarly,
+   _GL_VERIFY_TRUE works by packaging a _Static_assert inside a struct
+   that is an operand of sizeof.
+
+   The code below uses several ideas for C++ compilers, and for C
+   compilers that do not support _Static_assert:
+
+   * The first step is ((R) ? 1 : -1).  Given an expression R, of
+     integral or boolean or floating-point type, this yields an
+     expression of integral type, whose value is later verified to be
+     constant and nonnegative.
+
+   * Next this expression W is wrapped in a type
+     struct _gl_verify_type {
+       unsigned int _gl_verify_error_if_negative: W;
+     }.
+     If W is negative, this yields a compile-time error.  No compiler can
+     deal with a bit-field of negative size.
+
+     One might think that an array size check would have the same
+     effect, that is, that the type struct { unsigned int dummy[W]; }
+     would work as well.  However, inside a function, some compilers
+     (such as C++ compilers and GNU C) allow local parameters and
+     variables inside array size expressions.  With these compilers,
+     an array size check would not properly diagnose this misuse of
+     the verify macro:
+
+       void function (int n) { verify (n < 0); }
+
+   * For the verify macro, the struct _gl_verify_type will need to
+     somehow be embedded into a declaration.  To be portable, this
+     declaration must declare an object, a constant, a function, or a
+     typedef name.  If the declared entity uses the type directly,
+     such as in
+
+       struct dummy {...};
+       typedef struct {...} dummy;
+       extern struct {...} *dummy;
+       extern void dummy (struct {...} *);
+       extern struct {...} *dummy (void);
+
+     two uses of the verify macro would yield colliding declarations
+     if the entity names are not disambiguated.  A workaround is to
+     attach the current line number to the entity name:
+
+       #define _GL_CONCAT0(x, y) x##y
+       #define _GL_CONCAT(x, y) _GL_CONCAT0 (x, y)
+       extern struct {...} * _GL_CONCAT (dummy, __LINE__);
+
+     But this has the problem that two invocations of verify from
+     within the same macro would collide, since the __LINE__ value
+     would be the same for both invocations.  (The GCC __COUNTER__
+     macro solves this problem, but is not portable.)
+
+     A solution is to use the sizeof operator.  It yields a number,
+     getting rid of the identity of the type.  Declarations like
+
+       extern int dummy [sizeof (struct {...})];
+       extern void dummy (int [sizeof (struct {...})]);
+       extern int (*dummy (void)) [sizeof (struct {...})];
+
+     can be repeated.
+
+   * Should the implementation use a named struct or an unnamed struct?
+     Which of the following alternatives can be used?
+
+       extern int dummy [sizeof (struct {...})];
+       extern int dummy [sizeof (struct _gl_verify_type {...})];
+       extern void dummy (int [sizeof (struct {...})]);
+       extern void dummy (int [sizeof (struct _gl_verify_type {...})]);
+       extern int (*dummy (void)) [sizeof (struct {...})];
+       extern int (*dummy (void)) [sizeof (struct _gl_verify_type {...})];
+
+     In the second and sixth case, the struct type is exported to the
+     outer scope; two such declarations therefore collide.  GCC warns
+     about the first, third, and fourth cases.  So the only remaining
+     possibility is the fifth case:
+
+       extern int (*dummy (void)) [sizeof (struct {...})];
+
+   * GCC warns about duplicate declarations of the dummy function if
+     -Wredundant-decls is used.  GCC 4.3 and later have a builtin
+     __COUNTER__ macro that can let us generate unique identifiers for
+     each dummy function, to suppress this warning.
+
+   * This implementation exploits the fact that older versions of GCC,
+     which do not support _Static_assert, also do not warn about the
+     last declaration mentioned above.
+
+   * GCC warns if -Wnested-externs is enabled and 'verify' is used
+     within a function body; but inside a function, you can always
+     arrange to use verify_expr instead.
+
+   * In C++, any struct definition inside sizeof is invalid.
+     Use a template type to work around the problem.  */
+
+/* Concatenate two preprocessor tokens.  */
+#define _GL_CONCAT(x, y) _GL_CONCAT0 (x, y)
+#define _GL_CONCAT0(x, y) x##y
+
+/* _GL_COUNTER is an integer, preferably one that changes each time we
+   use it.  Use __COUNTER__ if it works, falling back on __LINE__
+   otherwise.  __LINE__ isn't perfect, but it's better than a
+   constant.  */
+#if defined __COUNTER__ && __COUNTER__ != __COUNTER__
+# define _GL_COUNTER __COUNTER__
+#else
+# define _GL_COUNTER __LINE__
+#endif
+
+/* Generate a symbol with the given prefix, making it unique if
+   possible.  */
+#define _GL_GENSYM(prefix) _GL_CONCAT (prefix, _GL_COUNTER)
+
+/* Verify requirement R at compile-time, as an integer constant expression
+   that returns 1.  If R is false, fail at compile-time, preferably
+   with a diagnostic that includes the string-literal DIAGNOSTIC.  */
+
+#define _GL_VERIFY_TRUE(R, DIAGNOSTIC) \
+   (!!sizeof (_GL_VERIFY_TYPE (R, DIAGNOSTIC)))
+
+#ifdef __cplusplus
+# if !GNULIB_defined_struct__gl_verify_type
+template <int w>
+  struct _gl_verify_type {
+    unsigned int _gl_verify_error_if_negative: w;
+  };
+#  define GNULIB_defined_struct__gl_verify_type 1
+# endif
+# define _GL_VERIFY_TYPE(R, DIAGNOSTIC) \
+    _gl_verify_type<(R) ? 1 : -1>
+#elif defined _GL_HAVE__STATIC_ASSERT
+# define _GL_VERIFY_TYPE(R, DIAGNOSTIC) \
+    struct {                                   \
+      _Static_assert (R, DIAGNOSTIC);          \
+      int _gl_dummy;                          \
+    }
+#else
+# define _GL_VERIFY_TYPE(R, DIAGNOSTIC) \
+    struct { unsigned int _gl_verify_error_if_negative: (R) ? 1 : -1; }
+#endif
+
+/* Verify requirement R at compile-time, as a declaration without a
+   trailing ';'.  If R is false, fail at compile-time.
+
+   This macro requires three or more arguments but uses at most the first
+   two, so that the _Static_assert macro optionally defined below supports
+   both the C11 two-argument syntax and the C23 one-argument syntax.
+
+   Unfortunately, unlike C11, this implementation must appear as an
+   ordinary declaration, and cannot appear inside struct { ... }.  */
+
+#if 202311 <= __STDC_VERSION__ || 200410 <= __cpp_static_assert
+# define _GL_VERIFY(R, DIAGNOSTIC, ...) static_assert (R, DIAGNOSTIC)
+#elif defined _GL_HAVE__STATIC_ASSERT
+# define _GL_VERIFY(R, DIAGNOSTIC, ...) _Static_assert (R, DIAGNOSTIC)
+#else
+# define _GL_VERIFY(R, DIAGNOSTIC, ...)                                \
+    extern int (*_GL_GENSYM (_gl_verify_function) (void))	       \
+      [_GL_VERIFY_TRUE (R, DIAGNOSTIC)]
+# if 4 < __GNUC__ + (6 <= __GNUC_MINOR__)
+#  pragma GCC diagnostic ignored "-Wnested-externs"
+# endif
+#endif
+
+/* _GL_STATIC_ASSERT_H is defined if this code is copied into assert.h.  */
+#ifdef _GL_STATIC_ASSERT_H
+/* Define _Static_assert if needed.  */
+/* With clang ≥ 3.8.0 in C++ mode, _Static_assert already works and accepts
+   1 or 2 arguments.  We better don't override it, because clang's standard
+   C++ library uses static_assert inside classes in several places, and our
+   replacement via _GL_VERIFY does not work in these contexts.  */
+# if (defined __cplusplus && defined __clang__ \
+      && (4 <= __clang_major__ + (8 <= __clang_minor__)))
+#  if 5 <= __clang_major__
+/* Avoid "warning: 'static_assert' with no message is a C++17 extension".  */
+#   pragma clang diagnostic ignored "-Wc++17-extensions"
+#  else
+/* Avoid "warning: static_assert with no message is a C++1z extension".  */
+#   pragma clang diagnostic ignored "-Wc++1z-extensions"
+#  endif
+# elif !defined _GL_HAVE__STATIC_ASSERT1 && !defined _Static_assert
+#  if !defined _MSC_VER || defined __clang__
+#   define _Static_assert(...) \
+      _GL_VERIFY (__VA_ARGS__, "static assertion failed", -)
+#  else
+    /* Work around MSVC preprocessor incompatibility with ISO C; see
+       <https://stackoverflow.com/questions/5134523/>.  */
+#   define _Static_assert(R, ...) \
+      _GL_VERIFY ((R), "static assertion failed", -)
+#  endif
+# endif
+/* Define static_assert if needed.  */
+# if (!defined static_assert \
+      && __STDC_VERSION__ < 202311 \
+      && (!defined __cplusplus \
+          || (__cpp_static_assert < 201411 \
+              && __GNUG__ < 6 && __clang_major__ < 6)))
+#  if defined __cplusplus && _MSC_VER >= 1900 && !defined __clang__
+/* MSVC 14 in C++ mode supports the two-arguments static_assert but not
+   the one-argument static_assert, and it does not support _Static_assert.
+   We have to play preprocessor tricks to distinguish the two cases.
+   Since the MSVC preprocessor is not ISO C compliant (see above),.
+   the solution is specific to MSVC.  */
+#   define _GL_EXPAND(x) x
+#   define _GL_SA1(a1) static_assert ((a1), "static assertion failed")
+#   define _GL_SA2 static_assert
+#   define _GL_SA3 static_assert
+#   define _GL_SA_PICK(x1,x2,x3,x4,...) x4
+#   define static_assert(...) _GL_EXPAND(_GL_SA_PICK(__VA_ARGS__,_GL_SA3,_GL_SA2,_GL_SA1)) (__VA_ARGS__)
+/* Avoid "fatal error C1189: #error:  The C++ Standard Library forbids macroizing keywords."  */
+#   define _ALLOW_KEYWORD_MACROS 1
+#  else
+#   define static_assert _Static_assert /* C11 requires this #define. */
+#  endif
+# endif
+#endif
+
+/* @assert.h omit start@  */
+
+#if defined __clang_major__ && __clang_major__ < 5
+# define _GL_HAS_BUILTIN_TRAP 0
+#elif 3 < __GNUC__ + (3 < __GNUC_MINOR__ + (4 <= __GNUC_PATCHLEVEL__))
+# define _GL_HAS_BUILTIN_TRAP 1
+#elif defined __has_builtin
+# define _GL_HAS_BUILTIN_TRAP __has_builtin (__builtin_trap)
+#else
+# define _GL_HAS_BUILTIN_TRAP 0
+#endif
+
+#ifndef _GL_HAS_BUILTIN_UNREACHABLE
+# if defined __clang_major__ && __clang_major__ < 5
+#  define _GL_HAS_BUILTIN_UNREACHABLE 0
+# elif 4 < __GNUC__ + (5 <= __GNUC_MINOR__)
+#  define _GL_HAS_BUILTIN_UNREACHABLE 1
+# elif defined __has_builtin
+#  define _GL_HAS_BUILTIN_UNREACHABLE __has_builtin (__builtin_unreachable)
+# else
+#  define _GL_HAS_BUILTIN_UNREACHABLE 0
+# endif
+#endif
+
+/* Each of these macros verifies that its argument R is nonzero.  To
+   be portable, R should be an integer constant expression.  Unlike
+   assert (R), there is no run-time overhead.
+
+   There are two macros, since no single macro can be used in all
+   contexts in C.  verify_expr (R, E) is for scalar contexts, including
+   integer constant expression contexts.  verify (R) is for declaration
+   contexts, e.g., the top level.  */
+
+/* Verify requirement R at compile-time.  Return the value of the
+   expression E.  */
+
+#define verify_expr(R, E) \
+   (_GL_VERIFY_TRUE (R, "verify_expr (" #R ", " #E ")") ? (E) : (E))
+
+/* Verify requirement R at compile-time, as a declaration without a
+   trailing ';'.  verify (R) acts like static_assert (R) except that
+   it is portable to C11/C++14 and earlier, it can issue better
+   diagnostics, and its name is shorter and may be more convenient.  */
+
+#ifdef __PGI
+/* PGI barfs if R is long.  */
+# define verify(R) _GL_VERIFY (R, "verify (...)", -)
+#else
+# define verify(R) _GL_VERIFY (R, "verify (" #R ")", -)
+#endif
+
+/* Assume that R always holds.  Behavior is undefined if R is false,
+   fails to evaluate, or has side effects.
+
+   'assume (R)' is a directive from the programmer telling the
+   compiler that R is true so the compiler needn't generate code to
+   test R.  This is why 'assume' is in verify.h: it's related to
+   static checking (in this case, static checking done by the
+   programmer), not dynamic checking.
+
+   'assume (R)' can affect compilation of all the code, not just code
+   that happens to be executed after the assume (R) is "executed".
+   For example, if the code mistakenly does 'assert (R); assume (R);'
+   the compiler is entitled to optimize away the 'assert (R)'.
+
+   Although assuming R can help a compiler generate better code or
+   diagnostics, performance can suffer if R uses hard-to-optimize
+   features such as function calls not inlined by the compiler.
+
+   Avoid Clang's __builtin_assume, as it breaks GNU Emacs master
+   as of 2020-08-23T21:09:49Z!eggert@cs.ucla.edu; see
+   <https://bugs.gnu.org/43152#71>.  It's not known whether this breakage
+   is a Clang bug or an Emacs bug; play it safe for now.  */
+
+#if _GL_HAS_BUILTIN_UNREACHABLE
+# define assume(R) ((R) ? (void) 0 : __builtin_unreachable ())
+#elif 1200 <= _MSC_VER
+# define assume(R) __assume (R)
+#elif 202311 <= __STDC_VERSION__
+# include <stddef.h>
+# define assume(R) ((R) ? (void) 0 : unreachable ())
+#elif (defined GCC_LINT || defined lint) && _GL_HAS_BUILTIN_TRAP
+  /* Doing it this way helps various packages when configured with
+     --enable-gcc-warnings, which compiles with -Dlint.  It's nicer
+     if 'assume' silences warnings with GCC 3.4 through GCC 4.4.7 (2012).  */
+# define assume(R) ((R) ? (void) 0 : __builtin_trap ())
+#else
+  /* Some older tools grok NOTREACHED, e.g., Oracle Studio 12.6 (2017).  */
+# define assume(R) ((R) ? (void) 0 : /*NOTREACHED*/ (void) 0)
+#endif
+
+/* @assert.h omit end@  */
+
+#endif