From: Jason Merrill <jason@redhat.com>
Date: Tue, 28 Jan 2025 22:46:59 +0000 (-0500)
Subject: c++: 'requires' diagnostic before C++20
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=47b62be9cace0e2e124650f331788d52ffd5fb25;p=thirdparty%2Fgcc.git

c++: 'requires' diagnostic before C++20

We were giving a generic "not declared" error for a requires-expression
without concepts enabled; we can do better.

gcc/cp/ChangeLog:

	* lex.cc (unqualified_name_lookup_error): Handle 'requires' better.
---

diff --git a/gcc/cp/lex.cc b/gcc/cp/lex.cc
index c12b084aad9..12af81ed078 100644
--- a/gcc/cp/lex.cc
+++ b/gcc/cp/lex.cc
@@ -749,6 +749,9 @@ unqualified_name_lookup_error (tree name, location_t loc)
 
   if (IDENTIFIER_ANY_OP_P (name))
     error_at (loc, "%qD not defined", name);
+  else if (!flag_concepts && name == ridpointers[(int)RID_REQUIRES])
+    error_at (loc, "%<requires%> only available with %<-std=c++20%> or "
+	      "%<-fconcepts%>");
   else
     {
       if (!objc_diagnose_private_ivar (name))