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c++: Concepts and local externs

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I discovered that we'd accept constraints on block-scope function
decls inside templates.  This fixes that.

	gcc/cp/
	* decl.c (grokfndecl): Don't attach to local extern.
This commit is contained in:
Nathan Sidwell 2020-09-11 13:42:59 -07:00
parent 2fda9e9bad
commit f76b0f231b
2 changed files with 48 additions and 4 deletions
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13
gcc/cp/decl.c
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@ -9457,7 +9457,10 @@ grokfndecl (tree ctype,
{
tree tmpl_reqs = NULL_TREE;
tree ctx = friendp ? current_class_type : ctype;
bool memtmpl = (processing_template_decl > template_class_depth (ctx));
bool block_local = TREE_CODE (current_scope ()) == FUNCTION_DECL;
bool memtmpl = (!block_local
&& (processing_template_decl
> template_class_depth (ctx)));
if (memtmpl)
tmpl_reqs = TEMPLATE_PARMS_CONSTRAINTS (current_template_parms);
tree ci = build_constraints (tmpl_reqs, decl_reqs);
@ -9467,9 +9470,11 @@ grokfndecl (tree ctype,
ci = NULL_TREE;
}
/* C++20 CA378: Remove non-templated constrained functions. */
if (ci && !flag_concepts_ts
&& (!processing_template_decl
|| (friendp && !memtmpl && !funcdef_flag)))
if (ci
&& (block_local
|| (!flag_concepts_ts
&& (!processing_template_decl
|| (friendp && !memtmpl && !funcdef_flag)))))
{
error_at (location, "constraints on a non-templated function");
ci = NULL_TREE;

39
gcc/testsuite/g++.dg/concepts/local-extern.C Normal file
View File

@ -0,0 +1,39 @@
// { dg-do compile { target c++17 } }
// { dg-additional-options -fconcepts }
// Don't attach constraints to block-scope fn-decls and ICE
template<typename _Iter>
concept input_or_output_iterator
= requires(_Iter __i) { { *__i } ; };
template<input_or_output_iterator _It>
class common_iterator
{
public:
void
frob ()
{
if (__builtin_is_constant_evaluated())
{
void __failed_assertion(); // ICEd
if (!bool(_M_index == 0)) __failed_assertion();
}
}
private:
unsigned char _M_index;
};
template <typename T> concept C = true;
template<typename T>
void F ()
{
void bad () requires C<T>; // { dg-error "a non-templated function" }
}