https://gcc.gnu.org/g:556248d7d2cf557423993eb68f6a55ae6bda0cee
commit r15-7482-g556248d7d2cf557423993eb68f6a55ae6bda0cee
Author: Jason Merrill <ja...@redhat.com>
Date: Tue Feb 11 13:51:32 2025 +0100
c++: don't default -frange-for-ext-temps in -std=gnu++20 [PR188574]
Since -frange-for-ext-temps has been causing trouble, let's not enable it
by default in pre-C++23 GNU modes for GCC 15, and also allow disabling it in
C++23 and up.
PR c++/188574
gcc/c-family/ChangeLog:
* c-opts.cc (c_common_post_options): Only enable
-frange-for-ext-temps by default in C++23.
gcc/ChangeLog:
* doc/invoke.texi: Adjust -frange-for-ext-temps documentation.
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/range-for3.C: Use -frange-for-ext-temps.
* g++.dg/cpp23/range-for4.C: Adjust expected result.
libgomp/ChangeLog:
* testsuite/libgomp.c++/range-for-4.C: Adjust expected result.
Diff:
---
gcc/doc/invoke.texi | 5 ++---
gcc/c-family/c-opts.cc | 17 +++--------------
gcc/testsuite/g++.dg/cpp23/range-for3.C | 4 ++--
gcc/testsuite/g++.dg/cpp23/range-for4.C | 4 ++--
libgomp/testsuite/libgomp.c++/range-for-4.C | 2 +-
5 files changed, 10 insertions(+), 22 deletions(-)
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 0aef2abf05b9..56d43cb67796 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -3548,9 +3548,8 @@ easier, you can use @option{-fno-pretty-templates} to
disable them.
Enable lifetime extension of C++ range based for temporaries.
With @option{-std=c++23} and above this is part of the language standard,
so lifetime of the temporaries is extended until the end of the loop
-regardless of this option. This option allows enabling that behavior also
-in earlier versions of the standard and is enabled by default in the
-GNU dialects, from @option{-std=gnu++11} until @option{-std=gnu++20}.
+by default. This option allows enabling that behavior also
+in earlier versions of the standard.
@opindex fno-rtti
@opindex frtti
diff --git a/gcc/c-family/c-opts.cc b/gcc/c-family/c-opts.cc
index 87b231861a64..d43b3aef1024 100644
--- a/gcc/c-family/c-opts.cc
+++ b/gcc/c-family/c-opts.cc
@@ -1213,20 +1213,9 @@ c_common_post_options (const char **pfilename)
if (cxx_dialect >= cxx20)
flag_concepts = 1;
- /* Enable lifetime extension of range based for temporaries for C++23.
- Diagnose -std=c++23 -fno-range-for-ext-temps. */
- if (cxx_dialect >= cxx23)
- {
- if (OPTION_SET_P (flag_range_for_ext_temps)
- && !flag_range_for_ext_temps)
- error ("%<-fno-range-for-ext-temps%> is incompatible with C++23");
- flag_range_for_ext_temps = 1;
- }
- /* Otherwise default to enabled in GNU modes but allow user to override. */
- else if (cxx_dialect >= cxx11
- && !flag_iso
- && !OPTION_SET_P (flag_range_for_ext_temps))
- flag_range_for_ext_temps = 1;
+ /* Enable lifetime extension of range based for temporaries for C++23. */
+ SET_OPTION_IF_UNSET (&global_options, &global_options_set,
+ flag_range_for_ext_temps, cxx_dialect >= cxx23);
/* -fimmediate-escalation has no effect when immediate functions are not
supported. */
diff --git a/gcc/testsuite/g++.dg/cpp23/range-for3.C
b/gcc/testsuite/g++.dg/cpp23/range-for3.C
index 301e25886ec6..f95b21b3ceee 100644
--- a/gcc/testsuite/g++.dg/cpp23/range-for3.C
+++ b/gcc/testsuite/g++.dg/cpp23/range-for3.C
@@ -1,7 +1,7 @@
// P2718R0 - Wording for P2644R1 Fix for Range-based for Loop
// { dg-do run { target c++11 } }
-// Verify -frange-for-ext-temps is set by default in -std=gnu++* modes.
-// { dg-options "" }
+// Verify -frange-for-ext-temps works in earlier standards.
+// { dg-additional-options "-frange-for-ext-temps" }
#define RANGE_FOR_EXT_TEMPS 1
#include "range-for1.C"
diff --git a/gcc/testsuite/g++.dg/cpp23/range-for4.C
b/gcc/testsuite/g++.dg/cpp23/range-for4.C
index f8c380d32c72..16204974bac9 100644
--- a/gcc/testsuite/g++.dg/cpp23/range-for4.C
+++ b/gcc/testsuite/g++.dg/cpp23/range-for4.C
@@ -1,7 +1,7 @@
// P2718R0 - Wording for P2644R1 Fix for Range-based for Loop
// { dg-do run { target c++11 } }
-// Verify -frange-for-ext-temps is set by default in -std=gnu++* modes.
+// Verify -frange-for-ext-temps is not set by default in -std=gnu++* modes.
// { dg-options "" }
-#define RANGE_FOR_EXT_TEMPS 1
+#define RANGE_FOR_EXT_TEMPS 0
#include "range-for2.C"
diff --git a/libgomp/testsuite/libgomp.c++/range-for-4.C
b/libgomp/testsuite/libgomp.c++/range-for-4.C
index 3c10e7349af7..aa6e4da523c1 100644
--- a/libgomp/testsuite/libgomp.c++/range-for-4.C
+++ b/libgomp/testsuite/libgomp.c++/range-for-4.C
@@ -3,5 +3,5 @@
// { dg-additional-options "-std=gnu++17" }
// { dg-require-effective-target tls_runtime }
-#define RANGE_FOR_EXT_TEMPS 1
+#define RANGE_FOR_EXT_TEMPS 0
#include "range-for-1.C"
