diff options
Diffstat (limited to 'compiler/rustc_hir_typeck/src/check.rs')
-rw-r--r-- | compiler/rustc_hir_typeck/src/check.rs | 133 |
1 files changed, 132 insertions, 1 deletions
diff --git a/compiler/rustc_hir_typeck/src/check.rs b/compiler/rustc_hir_typeck/src/check.rs index 32f86b804..57feefbca 100644 --- a/compiler/rustc_hir_typeck/src/check.rs +++ b/compiler/rustc_hir_typeck/src/check.rs @@ -1,4 +1,7 @@ use crate::coercion::CoerceMany; +use crate::errors::{ + LangStartIncorrectNumberArgs, LangStartIncorrectParam, LangStartIncorrectRetTy, +}; use crate::gather_locals::GatherLocalsVisitor; use crate::FnCtxt; use crate::GeneratorTypes; @@ -9,8 +12,9 @@ use rustc_hir::lang_items::LangItem; use rustc_hir_analysis::check::fn_maybe_err; use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; use rustc_infer::infer::RegionVariableOrigin; -use rustc_middle::ty::{self, Ty, TyCtxt}; +use rustc_middle::ty::{self, Binder, Ty, TyCtxt}; use rustc_span::def_id::LocalDefId; +use rustc_target::spec::abi::Abi; use rustc_trait_selection::traits; use std::cell::RefCell; @@ -168,6 +172,10 @@ pub(super) fn check_fn<'a, 'tcx>( check_panic_info_fn(tcx, panic_impl_did.expect_local(), fn_sig, decl, declared_ret_ty); } + if let Some(lang_start_defid) = tcx.lang_items().start_fn() && lang_start_defid == hir.local_def_id(fn_id).to_def_id() { + check_lang_start_fn(tcx, fn_sig, decl, fn_def_id); + } + gen_ty } @@ -223,3 +231,126 @@ fn check_panic_info_fn( tcx.sess.span_err(span, "should have no const parameters"); } } + +fn check_lang_start_fn<'tcx>( + tcx: TyCtxt<'tcx>, + fn_sig: ty::FnSig<'tcx>, + decl: &'tcx hir::FnDecl<'tcx>, + def_id: LocalDefId, +) { + let inputs = fn_sig.inputs(); + + let arg_count = inputs.len(); + if arg_count != 4 { + tcx.sess.emit_err(LangStartIncorrectNumberArgs { + params_span: tcx.def_span(def_id), + found_param_count: arg_count, + }); + } + + // only check args if they should exist by checking the count + // note: this does not handle args being shifted or their order swapped very nicely + // but it's a lang item, users shouldn't frequently encounter this + + // first arg is `main: fn() -> T` + if let Some(&main_arg) = inputs.get(0) { + // make a Ty for the generic on the fn for diagnostics + // FIXME: make the lang item generic checks check for the right generic *kind* + // for example `start`'s generic should be a type parameter + let generics = tcx.generics_of(def_id); + let fn_generic = generics.param_at(0, tcx); + let generic_tykind = + ty::Param(ty::ParamTy { index: fn_generic.index, name: fn_generic.name }); + let generic_ty = tcx.mk_ty(generic_tykind); + let expected_fn_sig = + tcx.mk_fn_sig([].iter(), &generic_ty, false, hir::Unsafety::Normal, Abi::Rust); + let expected_ty = tcx.mk_fn_ptr(Binder::dummy(expected_fn_sig)); + + // we emit the same error to suggest changing the arg no matter what's wrong with the arg + let emit_main_fn_arg_err = || { + tcx.sess.emit_err(LangStartIncorrectParam { + param_span: decl.inputs[0].span, + param_num: 1, + expected_ty: expected_ty, + found_ty: main_arg, + }); + }; + + if let ty::FnPtr(main_fn_sig) = main_arg.kind() { + let main_fn_inputs = main_fn_sig.inputs(); + if main_fn_inputs.iter().count() != 0 { + emit_main_fn_arg_err(); + } + + let output = main_fn_sig.output(); + output.map_bound(|ret_ty| { + // if the output ty is a generic, it's probably the right one + if !matches!(ret_ty.kind(), ty::Param(_)) { + emit_main_fn_arg_err(); + } + }); + } else { + emit_main_fn_arg_err(); + } + } + + // second arg is isize + if let Some(&argc_arg) = inputs.get(1) { + if argc_arg != tcx.types.isize { + tcx.sess.emit_err(LangStartIncorrectParam { + param_span: decl.inputs[1].span, + param_num: 2, + expected_ty: tcx.types.isize, + found_ty: argc_arg, + }); + } + } + + // third arg is `*const *const u8` + if let Some(&argv_arg) = inputs.get(2) { + let mut argv_is_okay = false; + if let ty::RawPtr(outer_ptr) = argv_arg.kind() { + if outer_ptr.mutbl.is_not() { + if let ty::RawPtr(inner_ptr) = outer_ptr.ty.kind() { + if inner_ptr.mutbl.is_not() && inner_ptr.ty == tcx.types.u8 { + argv_is_okay = true; + } + } + } + } + + if !argv_is_okay { + let inner_ptr_ty = + tcx.mk_ptr(ty::TypeAndMut { mutbl: hir::Mutability::Not, ty: tcx.types.u8 }); + let expected_ty = + tcx.mk_ptr(ty::TypeAndMut { mutbl: hir::Mutability::Not, ty: inner_ptr_ty }); + tcx.sess.emit_err(LangStartIncorrectParam { + param_span: decl.inputs[2].span, + param_num: 3, + expected_ty, + found_ty: argv_arg, + }); + } + } + + // fourth arg is `sigpipe: u8` + if let Some(&sigpipe_arg) = inputs.get(3) { + if sigpipe_arg != tcx.types.u8 { + tcx.sess.emit_err(LangStartIncorrectParam { + param_span: decl.inputs[3].span, + param_num: 4, + expected_ty: tcx.types.u8, + found_ty: sigpipe_arg, + }); + } + } + + // output type is isize + if fn_sig.output() != tcx.types.isize { + tcx.sess.emit_err(LangStartIncorrectRetTy { + ret_span: decl.output.span(), + expected_ty: tcx.types.isize, + found_ty: fn_sig.output(), + }); + } +} |