From: Alfie Richards <alfie.richards@arm.com>
Date: Thu, 13 Feb 2025 15:59:43 +0000 (+0000)
Subject: c++: Fix FMV return type ambiguation
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5abac04ffc7cc877ff5e1fa6562923b7b05b8289;p=thirdparty%2Fgcc.git

c++: Fix FMV return type ambiguation

Add logic for the case of two FMV annotated functions with identical
signature other than the return type.

Previously this was ignored, this changes the behavior to emit a diagnostic.

gcc/cp/ChangeLog:
	PR c++/119498
	* decl.cc (duplicate_decls): Change logic to not always exclude FMV
	annotated functions in cases of return type non-ambiguation.

gcc/testsuite/ChangeLog:
	PR c++/119498
	* g++.target/aarch64/pr119498.C: New test.
---

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 83c8e283b56..be26bd39b22 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -2014,8 +2014,10 @@ duplicate_decls (tree newdecl, tree olddecl, bool hiding, bool was_hidden)
 	    }
 	  /* For function versions, params and types match, but they
 	     are not ambiguous.  */
-	  else if ((!DECL_FUNCTION_VERSIONED (newdecl)
-		    && !DECL_FUNCTION_VERSIONED (olddecl))
+	  else if (((!DECL_FUNCTION_VERSIONED (newdecl)
+		     && !DECL_FUNCTION_VERSIONED (olddecl))
+		    || !same_type_p (fndecl_declared_return_type (newdecl),
+				     fndecl_declared_return_type (olddecl)))
 		   /* Let constrained hidden friends coexist for now, we'll
 		      check satisfaction later.  */
 		   && !member_like_constrained_friend_p (newdecl)
diff --git a/gcc/testsuite/g++.target/aarch64/pr119498.C b/gcc/testsuite/g++.target/aarch64/pr119498.C
new file mode 100644
index 00000000000..03f1659068d
--- /dev/null
+++ b/gcc/testsuite/g++.target/aarch64/pr119498.C
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-require-ifunc "" } */
+/* { dg-options "-O0" } */
+/* { dg-additional-options "-Wno-experimental-fmv-target" } */
+
+__attribute__ ((target_version ("default"))) int
+foo ();
+
+__attribute__ ((target_version ("default"))) int
+foo () { return 1; } /* { dg-message "old declaration" } */
+
+__attribute__ ((target_version ("dotprod"))) float
+foo () { return 3; } /* { dg-error "ambiguating new declaration" } */
+
+__attribute__ ((target_version ("sve"))) int
+foo2 () { return 1; } /* { dg-message "old declaration" } */
+
+__attribute__ ((target_version ("dotprod"))) float
+foo2 () { return 3; } /* { dg-error "ambiguating new declaration of" } */