c++: Disable deprecated/unavailable diagnostics when creating thunks for methods...

On the following testcase, we emit false positive warnings/errors about using
the deprecated or unavailable methods when creating thunks for them, even
when nothing (in the testcase so far) actually used those.

The following patch temporarily disables that diagnostics when creating
the thunks.

2024-09-12  Jakub Jelinek  <jakub@redhat.com>

	PR c++/116636
	* method.cc: Include decl.h.
	(use_thunk): Temporarily change deprecated_state to
	UNAVAILABLE_DEPRECATED_SUPPRESS.

	* g++.dg/warn/deprecated-19.C: New test.

diff --git a/gcc/cp/method.cc b/gcc/cp/method.cc
index 68a776d2c5a6a4f5522aa7645800d43aebb32602..21c06c744c9a98ba20353ef78dbd71419dea1b89 100644 (file)
--- a/gcc/cp/method.cc
+++ b/gcc/cp/method.cc
@@ -26,6 +26,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "coretypes.h"
 #include "target.h"
 #include "cp-tree.h"
+#include "decl.h"
 #include "stringpool.h"
 #include "cgraph.h"
 #include "varasm.h"
@@ -283,6 +284,11 @@ use_thunk (tree thunk_fndecl, bool emit_p)
   /* Thunks are always addressable; they only appear in vtables.  */
   TREE_ADDRESSABLE (thunk_fndecl) = 1;
 
+  /* Don't diagnose deprecated or unavailable functions just because they
+     have thunks emitted for them.  */
+  auto du = make_temp_override (deprecated_state,
+                                UNAVAILABLE_DEPRECATED_SUPPRESS);
+
   /* Figure out what function is being thunked to.  It's referenced in
      this translation unit.  */
   TREE_ADDRESSABLE (function) = 1;

diff --git a/gcc/testsuite/g++.dg/warn/deprecated-19.C b/gcc/testsuite/g++.dg/warn/deprecated-19.C
new file mode 100644 (file)
index 0000000..561f124
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/deprecated-19.C
@@ -0,0 +1,22 @@
+// PR c++/116636
+// { dg-do compile }
+// { dg-options "-pedantic -Wdeprecated" }
+
+struct A {
+  virtual int foo () = 0;
+};
+struct B : virtual A {
+  [[deprecated]] int foo () { return 0; }      // { dg-message "declared here" }
+};                                             // { dg-warning "C\\\+\\\+11 attributes only available with" "" { target c++98_only } .-1 }
+struct C : virtual A {
+  [[gnu::unavailable]] int foo () { return 0; }        // { dg-message "declared here" }
+};                                             // { dg-warning "C\\\+\\\+11 attributes only available with" "" { target c++98_only } .-1 }
+
+void
+bar ()
+{
+  B b;
+  b.foo ();                                    // { dg-warning "'virtual int B::foo\\\(\\\)' is deprecated" }
+  C c;
+  c.foo ();                                    // { dg-error "'virtual int C::foo\\\(\\\)' is unavailable" }
+}