On Mon, May 18, 2020 at 03:51:36PM -0400, Jason Merrill wrote:
> On 5/16/20 6:34 PM, Marek Polacek wrote:
> > Since GCC 9, C++17 support is no longer experimental. It was too late
> > to change the default C++ dialect to C++17 in GCC 10, but I think now
> > it's time to pull the trigger (C++14 was made the default in GCC 6.1).
> > We're still missing two C++17 library features, but that shouldn't stop
> > us. See
> > <https://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#status.iso.2017>
> > and
> > <https://gcc.gnu.org/projects/cxx-status.html#cxx17>
> > for the C++17 status.
> >
> > I won't list all C++17 features here, but just a few heads-up:
> >
> > - trigraphs were removed (hardly anyone cares, unless your keyboard is
> > missing the # key),
> > - operator++(bool) was removed (so some tests now run in C++14 and down
> > only),
> > - the keyword register was removed (some legacy code might trip on
> > this),
> > - noexcept specification is now part of the type system and C++17 does
> > not allow dynamic exception specifications anymore (the empty throw
> > specification is still available, but it is deprecated),
> > - the evaluation order rules are different in C++17,
> > - static constexpr data members are now implicitly inline (which makes
> > them definitions),
> > - C++17 requires guaranteed copy elision, meaning that a copy/move
> > constructor call might be elided completely. That means that if
> > something relied on a constructor being instantiated via e.g. copying
> > a function parameter, it might now fail.
> >
> > Jakub, the last point is actually what I encountered in for-27.C and it
> > looks like an OpenMP issue, in that it wrongly depends on an implicit
> > instantiation. Am I mistaken?
> >
> > Due to the 'register' removal, this patch depends on the regenerated
> > cfns.h version I posted earlier today.
> >
> > I'll post an update for cxx-status.html and add a new caveat to changes.html
> > once this is in.
> >
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, aarch64-unknown-linux-gnu,
> > and powerpc64le-unknown-linux-gnu. Ok for trunk?
> >
> > * doc/invoke.texi (C Dialect Options): Adjust -std default for C++.
> > * doc/standards.texi (C Language): Correct the default dialect.
> > (C++ Language): Update the default for C++ to gnu++17.
> >
> > * c-opts.c (c_common_init_options): Default to gnu++17.
> >
> > * c-c++-common/torture/vector-subscript-3.c: Remove the register
> > keywords.
> > * g++.dg/cpp1z/attributes-enum-1a.C: Update for C++17.
> > * g++.dg/cpp1z/fold7a.C: Likewise.
> > * g++.dg/cpp1z/nontype3a.C: Likewise.
> > * g++.dg/cpp1z/utf8-2a.C: Likewise.
> > * g++.dg/parse/error11.C: Use c++14_down.
> > * g++.dg/torture/pr34850.C: Add -Wno-attribute-warning.
> > * g++.dg/torture/pr49394.C: Add dg-warning.
> > * g++.dg/torture/pr82154.C: Use -std=c++14.
> > * g++.dg/ubsan/pr85029.C: Use -Wno-register.
> > * g++.dg/ubsan/vptr-12.C: Use -fstrong-eval-order=some.
> > * lib/target-supports.exp: Set to C++17.
> > * obj-c++.dg/try-catch-9.mm: Use -Wno-register.
> >
> > * testsuite/libgomp.c++/atomic-3.C: Use -std=gnu++14.
> > * testsuite/libgomp.c++/for-27.C: Explicitly instantiate the
> > copy constructor for I<int>.
> > ---
> > gcc/c-family/c-opts.c | 4 ++--
> > gcc/doc/invoke.texi | 2 +-
> > gcc/doc/standards.texi | 4 ++--
> > gcc/testsuite/c-c++-common/torture/vector-subscript-3.c | 6 +++---
> > gcc/testsuite/g++.dg/cpp1z/attributes-enum-1a.C | 4 ++--
> > gcc/testsuite/g++.dg/cpp1z/fold7a.C | 4 ++--
> > gcc/testsuite/g++.dg/cpp1z/nontype3a.C | 4 ++--
> > gcc/testsuite/g++.dg/cpp1z/utf8-2a.C | 4 ++--
> > gcc/testsuite/g++.dg/parse/error11.C | 5 +++--
> > gcc/testsuite/g++.dg/torture/pr34850.C | 2 +-
> > gcc/testsuite/g++.dg/torture/pr49394.C | 2 +-
> > gcc/testsuite/g++.dg/torture/pr82154.C | 3 ++-
> > gcc/testsuite/g++.dg/ubsan/pr85029.C | 2 +-
> > gcc/testsuite/g++.dg/ubsan/vptr-12.C | 2 +-
> > gcc/testsuite/lib/target-supports.exp | 2 +-
> > gcc/testsuite/obj-c++.dg/try-catch-9.mm | 2 +-
> > libgomp/testsuite/libgomp.c++/atomic-3.C | 3 ++-
> > libgomp/testsuite/libgomp.c++/for-27.C | 6 ++++++
> > 18 files changed, 35 insertions(+), 26 deletions(-)
> >
> > diff --git a/gcc/c-family/c-opts.c b/gcc/c-family/c-opts.c
> > index 7695e88c130..5b266c06f3b 100644
> > --- a/gcc/c-family/c-opts.c
> > +++ b/gcc/c-family/c-opts.c
> > @@ -256,9 +256,9 @@ c_common_init_options (unsigned int
> > decoded_options_count,
> > }
> > }
> > - /* Set C++ standard to C++14 if not specified on the command line. */
> > + /* Set C++ standard to C++17 if not specified on the command line. */
> > if (c_dialect_cxx ())
> > - set_std_cxx14 (/*ISO*/false);
> > + set_std_cxx17 (/*ISO*/false);
> > global_dc->colorize_source_p = true;
> > }
> > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> > index 850aeac033d..97e13421323 100644
> > --- a/gcc/doc/invoke.texi
> > +++ b/gcc/doc/invoke.texi
> > @@ -2057,7 +2057,6 @@ The name @samp{c++1y} is deprecated.
> > @item gnu++14
> > @itemx gnu++1y
> > GNU dialect of @option{-std=c++14}.
> > -This is the default for C++ code.
> > The name @samp{gnu++1y} is deprecated.
> > @item c++17
> > @@ -2068,6 +2067,7 @@ The name @samp{c++1z} is deprecated.
> > @item gnu++17
> > @itemx gnu++1z
> > GNU dialect of @option{-std=c++17}.
> > +This is the default for C++ code.
> > The name @samp{gnu++1z} is deprecated.
> > @item c++20
> > diff --git a/gcc/doc/standards.texi b/gcc/doc/standards.texi
> > index f39d8b378f1..fc5016028dd 100644
> > --- a/gcc/doc/standards.texi
> > +++ b/gcc/doc/standards.texi
> > @@ -130,7 +130,7 @@ select an extended version of the C language explicitly
> > with
> > extensions).
> > The default, if no C language dialect options are given,
> > -is @option{-std=gnu11}.
> > +is @option{-std=gnu17}.
>
> I don't think you mean to change the default C dialect.
The current default C dialect already is gnu17, here I was just correcting that
as a drive-by. I can commit it separately if you prefer.
> > The ISO C standard defines (in clause 4) two classes of conforming
> > implementation. A @dfn{conforming hosted implementation} supports the
> > @@ -246,7 +246,7 @@ select an extended version of the C++ language
> > explicitly with
> > @option{-std=gnu++17} (for C++17 with GNU extensions).
> > The default, if
> > -no C++ language dialect options are given, is @option{-std=gnu++14}.
> > +no C++ language dialect options are given, is @option{-std=gnu++17}.
> > @section Objective-C and Objective-C++ Languages
> > @cindex Objective-C
> > diff --git a/gcc/testsuite/c-c++-common/torture/vector-subscript-3.c
> > b/gcc/testsuite/c-c++-common/torture/vector-subscript-3.c
> > index bb5c91485d7..12779af5438 100644
> > --- a/gcc/testsuite/c-c++-common/torture/vector-subscript-3.c
> > +++ b/gcc/testsuite/c-c++-common/torture/vector-subscript-3.c
> > @@ -12,9 +12,9 @@ struct vec_s {
> > int main () {
> > - register short vector v0 = {1,2,3,4,5,6,7};
> > - register myvec_t v1 = {1,2,3,4,5,6,7};
> > - register struct vec_s v2;
> > + short vector v0 = {1,2,3,4,5,6,7};
> > + myvec_t v1 = {1,2,3,4,5,6,7};
> > + struct vec_s v2;
>
> I'd be careful about changing a c-c++-common torture test like this. Maybe
> #define away register for C++17 and up, or add -Wno-register in C++ mode
> like you do for other testcases?
Done.
> > v2.member = v1;
> > diff --git a/gcc/testsuite/g++.dg/cpp1z/attributes-enum-1a.C
> > b/gcc/testsuite/g++.dg/cpp1z/attributes-enum-1a.C
> > index aacfac875b1..4d7e547920f 100644
> > --- a/gcc/testsuite/g++.dg/cpp1z/attributes-enum-1a.C
> > +++ b/gcc/testsuite/g++.dg/cpp1z/attributes-enum-1a.C
> > @@ -1,5 +1,5 @@
> > -// This macro should not be defined without -std=c++17.
> > +// This macro should be defined with -std=c++17.
> > -#ifdef __cpp_enumerator_attributes
> > +#ifndef __cpp_enumerator_attributes
>
> You're turning this file into the same test as attributes-enum-1.C, and it's
> intended to be the complementary test. Instead, restrict the test to
> pre-C++17.
Indeed, that was sloppy. This test (and the other) is now c++14_down. It was
annoying to find out that only adding the target didn't suffice -- it seems
that dejagnu's proc check-flags happily accepts -std flags in comments too, so
it thought that we specified -std=c++17 and it didn't run the test in any other
mode. Fixed by tweaking the comment...
> > #error __cpp_enumerator_attributes defined
> > #endif
> > diff --git a/gcc/testsuite/g++.dg/cpp1z/fold7a.C
> > b/gcc/testsuite/g++.dg/cpp1z/fold7a.C
> > index 5c782ff0969..530741d3907 100644
> > --- a/gcc/testsuite/g++.dg/cpp1z/fold7a.C
> > +++ b/gcc/testsuite/g++.dg/cpp1z/fold7a.C
> > @@ -1,5 +1,5 @@
> > -// This macro should not be defined without -std=c++17.
> > +// This macro should be defined with -std=c++17.
> > -#ifdef __cpp_fold_expressions
> > +#ifndef __cpp_fold_expressions
>
> Likewise.
^
> > #error __cpp_fold_expressions defined
> > #endif
> > diff --git a/gcc/testsuite/g++.dg/cpp1z/nontype3a.C
> > b/gcc/testsuite/g++.dg/cpp1z/nontype3a.C
> > index a704e5045b6..7b640e551b6 100644
> > --- a/gcc/testsuite/g++.dg/cpp1z/nontype3a.C
> > +++ b/gcc/testsuite/g++.dg/cpp1z/nontype3a.C
> > @@ -1,5 +1,5 @@
> > -// This macro should not be defined without -std=c++17.
> > +// This macro should be defined with -std=c++17.
> > -#ifdef __cpp_nontype_template_args
> > +#ifndef __cpp_nontype_template_args
>
> Likewise.
^
> > #error __cpp_nontype_template_args defined
> > #endif
> > diff --git a/gcc/testsuite/g++.dg/cpp1z/utf8-2a.C
> > b/gcc/testsuite/g++.dg/cpp1z/utf8-2a.C
> > index 0e243d68a75..c4a8f46fb7d 100644
> > --- a/gcc/testsuite/g++.dg/cpp1z/utf8-2a.C
> > +++ b/gcc/testsuite/g++.dg/cpp1z/utf8-2a.C
> > @@ -1,5 +1,5 @@
> > -// This macro should not be 201411 without -std=c++17.
> > +// This macro should be 201411 with -std=c++17.
> > -#if __cpp_unicode_characters == 201411
> > +#if __cpp_unicode_characters != 201411
>
> Likewise.
^
> > #error Wrong value for __cpp_unicode_characters
> > #endif
> > diff --git a/gcc/testsuite/g++.dg/parse/error11.C
> > b/gcc/testsuite/g++.dg/parse/error11.C
> > index 1a49d6edb12..4e2a7f8b75f 100644
> > --- a/gcc/testsuite/g++.dg/parse/error11.C
> > +++ b/gcc/testsuite/g++.dg/parse/error11.C
> > @@ -1,5 +1,6 @@
> > -// { dg-do compile }
> > -// { dg-options "-fshow-column" }"
> > +// { dg-do compile { target c++14_down } }
> > +// C++17 removed trigraphs.
>
> There are no trigraphs in this testcase, and digraphs are still part of
> C++20.
True. In C++17 we issue slightly different diagnostics for lines 51 and 52,
and I thought it was so because trigraphs had been removed. I've updated
the expected error messages instead. Is that acceptable?
> > +// { dg-options "-fshow-column" }
> > // Origin: Giovanni Bajo <giovannibajo at gcc dot gnu dot org>
> > // Try to find out when the digraph '<:' is used as a mistake, and parse
> > it
> > // correctly to avoid cascaded errors.
> > diff --git a/gcc/testsuite/g++.dg/torture/pr34850.C
> > b/gcc/testsuite/g++.dg/torture/pr34850.C
> > index c4d808c5a0d..59dd5dfde7d 100644
> > --- a/gcc/testsuite/g++.dg/torture/pr34850.C
> > +++ b/gcc/testsuite/g++.dg/torture/pr34850.C
> > @@ -1,6 +1,6 @@
> > /* { dg-do compile } */
> > /* { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
> > -/* { dg-options "-ffat-lto-objects -Wno-return-type" } */
> > +/* { dg-options "-ffat-lto-objects -Wno-return-type
> > -Wno-attribute-warning" } */
>
> Why?
Sorry, this was non-obvious.
This boils down to
void __warn_memset_zero_len() __attribute__((__warning__("")));
long b;
void foo() throw()
{
if (__builtin_constant_p(b))
__warn_memset_zero_len();
}
int bar() { foo(); }
In C++17, with -O2, we give
t.C:6:27: warning: call to '__warn_memset_zero_len' declared with attribute
warning: [-Wattribute-warning]
6 | __warn_memset_zero_len();
while in C++14 we don't. We behave differently due to...
26006 /* In C++17, throw() is equivalent to noexcept (true). throw()
26007 is deprecated in C++11 and above as well, but is still widely used,
26008 so don't warn about it yet. */
26009 else if (cxx_dialect >= cxx17)
26010 type_id_list = noexcept_true_spec;
26011 else
26012 type_id_list = empty_except_spec;
...and different optimizations based on that. In C++17, we inline foo, and
then CCP folds the __builtin_constant_p call and we end up with
bar () {
__warn_memset_zero_len ();
__builtin_unreachable ();
}
and since __warn_memset_zero_len is marked with the warning attribute,
expand_expr_real_1 warns.
In C++14 we don't inline foo, but VRP removes the code inside foo, DCE then
elides the call to foo completely, and we end up without the call to
__warn_memset_zero_len so we don't warn.
Note that bar misses a return statement, which can be UB at runtime. This
doesn't strike me as a C++ FE issue.
> > typedef unsigned char uint8_t;
> > typedef unsigned int uint32_t;
> > diff --git a/gcc/testsuite/g++.dg/torture/pr49394.C
> > b/gcc/testsuite/g++.dg/torture/pr49394.C
> > index 7bd8fd4dc72..32e1a98ce05 100644
> > --- a/gcc/testsuite/g++.dg/torture/pr49394.C
> > +++ b/gcc/testsuite/g++.dg/torture/pr49394.C
> > @@ -10,7 +10,7 @@ struct Mutex
> > #endif
> > {
> > if (locked)
> > - throw 0;
> > + throw 0; // { dg-warning ".throw. will always call .terminate." "" {
> > target c++17 } }
>
> Instead, the destructor should be noexcept(false) in C++17 and up.
Fixed.
> > }
> > void lock ()
> > {
> > diff --git a/gcc/testsuite/g++.dg/torture/pr82154.C
> > b/gcc/testsuite/g++.dg/torture/pr82154.C
> > index e229c3e640e..698340d8c65 100644
> > --- a/gcc/testsuite/g++.dg/torture/pr82154.C
> > +++ b/gcc/testsuite/g++.dg/torture/pr82154.C
> > @@ -1,5 +1,6 @@
> > // { dg-do compile }
> > -// { dg-additional-options "-Wno-deprecated" }
> > +// { dg-additional-options "-std=c++14 -Wno-deprecated" }
> > +// C++17 does not allow dynamic exception specification.
> > namespace a {
> > int b;
> > diff --git a/gcc/testsuite/g++.dg/ubsan/pr85029.C
> > b/gcc/testsuite/g++.dg/ubsan/pr85029.C
> > index 07472af16a5..836ce69cc15 100644
> > --- a/gcc/testsuite/g++.dg/ubsan/pr85029.C
> > +++ b/gcc/testsuite/g++.dg/ubsan/pr85029.C
> > @@ -1,7 +1,7 @@
> > // PR sanitizer/85029
> > // { dg-do compile }
> > // { dg-skip-if "" { *-*-* } { "-flto -fno-fat-lto-objects" } }
> > -// { dg-options "-fsanitize=undefined" }
> > +// { dg-options "-fsanitize=undefined -Wno-register" }
> > struct B {
> > virtual B bar ();
> > diff --git a/gcc/testsuite/g++.dg/ubsan/vptr-12.C
> > b/gcc/testsuite/g++.dg/ubsan/vptr-12.C
> > index f23bbc3fd10..ce57ba87db0 100644
> > --- a/gcc/testsuite/g++.dg/ubsan/vptr-12.C
> > +++ b/gcc/testsuite/g++.dg/ubsan/vptr-12.C
> > @@ -1,6 +1,6 @@
> > // { dg-do run }
> > // { dg-shouldfail "ubsan" }
> > -// { dg-options "-fsanitize=vptr -fno-sanitize-recover=vptr" }
> > +// { dg-options "-fsanitize=vptr -fno-sanitize-recover=vptr
> > -fstrong-eval-order=some" }
>
> Why? I can't see anything in this testcase that should be affected by
> -fstrong-eval-order.
I think this points to a bug; I'd been meaning to come back to it but
apparently I never did.
I've investigated more now and opened https://gcc.gnu.org/PR95221 along with
my initial analysis. I'm uncertain if this one should be a blocker for the
default change -- valid code should never hit it, after all --, though...
> > struct MyClass
> > {
> > diff --git a/gcc/testsuite/lib/target-supports.exp
> > b/gcc/testsuite/lib/target-supports.exp
> > index 3e91a81dd5a..4191600fcd9 100644
> > --- a/gcc/testsuite/lib/target-supports.exp
> > +++ b/gcc/testsuite/lib/target-supports.exp
> > @@ -9018,7 +9018,7 @@ proc check_effective_target_c++ { } {
> > return 0
> > }
> > -set cxx_default "c++14"
> > +set cxx_default "c++17"
> > # Check whether the current active language standard supports the features
> > # of C++11/C++14 by checking for the presence of one of the -std flags.
> > # This assumes that the default for the compiler is $cxx_default, and that
> > diff --git a/gcc/testsuite/obj-c++.dg/try-catch-9.mm
> > b/gcc/testsuite/obj-c++.dg/try-catch-9.mm
> > index 73c7c991709..b2dc61b9989 100644
> > --- a/gcc/testsuite/obj-c++.dg/try-catch-9.mm
> > +++ b/gcc/testsuite/obj-c++.dg/try-catch-9.mm
> > @@ -6,7 +6,7 @@
> > /* { dg-xfail-run-if "PR23616" { *-*-* } { "-fgnu-runtime" } {
> > "-fnext-runtime" } } */
> > /* { dg-xfail-if "Needs OBJC2 ABI" { *-*-darwin* && { lp64 && { ! objc2 }
> > } } { "-fnext-runtime" "-fgnu-runtime" } { "" } }
> > /* { dg-prune-output ".*internal compiler error.*" } */
> > -/* { dg-options "-fobjc-exceptions -O2" } */
> > +/* { dg-options "-fobjc-exceptions -O2 -Wno-register" } */
> > #include "../objc-obj-c++-shared/TestsuiteObject.m"
> > #include <stdlib.h>
> > diff --git a/libgomp/testsuite/libgomp.c++/atomic-3.C
> > b/libgomp/testsuite/libgomp.c++/atomic-3.C
> > index f957b2fece5..c02532d3206 100644
> > --- a/libgomp/testsuite/libgomp.c++/atomic-3.C
> > +++ b/libgomp/testsuite/libgomp.c++/atomic-3.C
> > @@ -1,5 +1,6 @@
> > // { dg-do run }
> > -// { dg-options "-Wno-deprecated" }
> > +// C++17 forbids ++ on bool.
> > +// { dg-options "-Wno-deprecated -std=gnu++14" }
> > extern "C" void abort (void);
> > bool v, x1, x2, x3, x4, x5, x6;
> > diff --git a/libgomp/testsuite/libgomp.c++/for-27.C
> > b/libgomp/testsuite/libgomp.c++/for-27.C
> > index 7dca4305f85..d286346e63a 100644
> > --- a/libgomp/testsuite/libgomp.c++/for-27.C
> > +++ b/libgomp/testsuite/libgomp.c++/for-27.C
> > @@ -151,6 +151,12 @@ f4 (const I<int> &x, const I<int> &y)
> > else if (results[i]) \
> > abort ()
> > +// FIXME: OpenMP seems to count on this being instantiated; the copy
> > +// constructor is called in functions fn2/fn3/fn4. But in C++17 we
> > +// elide this copy constructor, so it's never been instantiated. For
> > +// now instantiate it explicitly.
>
> This sounds like a bug that needs to be fixed before the default can change.
> I guess the openmp code needs to mark_used the copy constructor or the like.
...this makes sense. I've opened https://gcc.gnu.org/PR95197 to handle this;
I think either Jakub or I should be able to fix it before long.
Bootstrapped/regtested on x86_64-pc-linux-gnu.
-- >8 --
Since GCC 9, C++17 support is no longer experimental. It was too late
to change the default C++ dialect to C++17 in GCC 10, but I think now
it's time to pull the trigger (C++14 was made the default in GCC 6.1).
We're still missing two C++17 library features, but that shouldn't stop
us. See
<https://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#status.iso.2017>
and
<https://gcc.gnu.org/projects/cxx-status.html#cxx17>
for the C++17 status.
I won't list all C++17 features here, but just a few heads-up:
- trigraphs were removed (hardly anyone cares, unless your keyboard is
missing the # key),
- operator++(bool) was removed (so some tests now run in C++14 and down
only),
- the keyword register was removed (some legacy code might trip on
this),
- noexcept specification is now part of the type system and C++17 does
not allow dynamic exception specifications anymore (the empty throw
specification is still available, but it is deprecated),
- the evaluation order rules are different in C++17,
- static constexpr data members are now implicitly inline (which makes
them definitions),
- C++17 requires guaranteed copy elision, meaning that a copy/move
constructor call might be elided completely. That means that if
something relied on a constructor being instantiated via e.g. copying
a function parameter, it might now fail.
I'll post an update for cxx-status.html and add a new caveat to changes.html
once this is in.
* doc/invoke.texi (C Dialect Options): Adjust -std default for C++.
* doc/standards.texi (C Language): Correct the default dialect.
(C++ Language): Update the default for C++ to gnu++17.
* c-opts.c (c_common_init_options): Default to gnu++17.
* c-c++-common/torture/vector-subscript-3.c: In C++17, define away
the keyword register.
* g++.dg/cpp1z/attributes-enum-1a.C: Only run pre-C++17.
* g++.dg/cpp1z/fold7a.C: Likewise.
* g++.dg/cpp1z/nontype3a.C: Likewise.
* g++.dg/cpp1z/utf8-2a.C: Likewise.
* g++.dg/parse/error11.C: Update expected diagnostics for C++17.
* g++.dg/torture/pr34850.C: Add -Wno-attribute-warning.
* g++.dg/torture/pr49394.C: In C++17, use noexcept(false).
* g++.dg/torture/pr82154.C: Use -std=c++14.
* g++.dg/ubsan/pr85029.C: Use -Wno-register.
* g++.dg/ubsan/vptr-12.C: Use -fstrong-eval-order=some. Adjust
dg-output.
* lib/target-supports.exp: Set to C++17.
* obj-c++.dg/try-catch-9.mm: Use -Wno-register.
* testsuite/libgomp.c++/atomic-3.C: Use -std=gnu++14.
---
gcc/c-family/c-opts.c | 4 ++--
gcc/doc/invoke.texi | 2 +-
gcc/doc/standards.texi | 4 ++--
.../c-c++-common/torture/vector-subscript-3.c | 3 +++
.../g++.dg/cpp1z/attributes-enum-1a.C | 3 ++-
gcc/testsuite/g++.dg/cpp1z/fold7a.C | 3 ++-
gcc/testsuite/g++.dg/cpp1z/nontype3a.C | 3 ++-
gcc/testsuite/g++.dg/cpp1z/utf8-2a.C | 3 ++-
gcc/testsuite/g++.dg/parse/error11.C | 18 +++++++++++-------
gcc/testsuite/g++.dg/torture/pr34850.C | 2 +-
gcc/testsuite/g++.dg/torture/pr49394.C | 2 ++
gcc/testsuite/g++.dg/torture/pr82154.C | 3 ++-
gcc/testsuite/g++.dg/ubsan/pr85029.C | 2 +-
gcc/testsuite/g++.dg/ubsan/vptr-12.C | 5 +++--
gcc/testsuite/lib/target-supports.exp | 2 +-
gcc/testsuite/obj-c++.dg/try-catch-9.mm | 2 +-
libgomp/testsuite/libgomp.c++/atomic-3.C | 3 ++-
17 files changed, 40 insertions(+), 24 deletions(-)
diff --git a/gcc/c-family/c-opts.c b/gcc/c-family/c-opts.c
index 7695e88c130..5b266c06f3b 100644
--- a/gcc/c-family/c-opts.c
+++ b/gcc/c-family/c-opts.c
@@ -256,9 +256,9 @@ c_common_init_options (unsigned int decoded_options_count,
}
}
- /* Set C++ standard to C++14 if not specified on the command line. */
+ /* Set C++ standard to C++17 if not specified on the command line. */
if (c_dialect_cxx ())
- set_std_cxx14 (/*ISO*/false);
+ set_std_cxx17 (/*ISO*/false);
global_dc->colorize_source_p = true;
}
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 7217e27151d..c1acb8a70c2 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -2057,7 +2057,6 @@ The name @samp{c++1y} is deprecated.
@item gnu++14
@itemx gnu++1y
GNU dialect of @option{-std=c++14}.
-This is the default for C++ code.
The name @samp{gnu++1y} is deprecated.
@item c++17
@@ -2068,6 +2067,7 @@ The name @samp{c++1z} is deprecated.
@item gnu++17
@itemx gnu++1z
GNU dialect of @option{-std=c++17}.
+This is the default for C++ code.
The name @samp{gnu++1z} is deprecated.
@item c++20
diff --git a/gcc/doc/standards.texi b/gcc/doc/standards.texi
index f39d8b378f1..fc5016028dd 100644
--- a/gcc/doc/standards.texi
+++ b/gcc/doc/standards.texi
@@ -130,7 +130,7 @@ select an extended version of the C language explicitly with
extensions).
The default, if no C language dialect options are given,
-is @option{-std=gnu11}.
+is @option{-std=gnu17}.
The ISO C standard defines (in clause 4) two classes of conforming
implementation. A @dfn{conforming hosted implementation} supports the
@@ -246,7 +246,7 @@ select an extended version of the C++ language explicitly
with
@option{-std=gnu++17} (for C++17 with GNU extensions).
The default, if
-no C++ language dialect options are given, is @option{-std=gnu++14}.
+no C++ language dialect options are given, is @option{-std=gnu++17}.
@section Objective-C and Objective-C++ Languages
@cindex Objective-C
diff --git a/gcc/testsuite/c-c++-common/torture/vector-subscript-3.c
b/gcc/testsuite/c-c++-common/torture/vector-subscript-3.c
index bb5c91485d7..05d24f49011 100644
--- a/gcc/testsuite/c-c++-common/torture/vector-subscript-3.c
+++ b/gcc/testsuite/c-c++-common/torture/vector-subscript-3.c
@@ -10,6 +10,9 @@ struct vec_s {
vector short member;
};
+#if defined(__cplusplus) && __cplusplus >= 201703L
+#define register /* nothing */
+#endif
int main () {
register short vector v0 = {1,2,3,4,5,6,7};
diff --git a/gcc/testsuite/g++.dg/cpp1z/attributes-enum-1a.C
b/gcc/testsuite/g++.dg/cpp1z/attributes-enum-1a.C
index aacfac875b1..20f0b1d8876 100644
--- a/gcc/testsuite/g++.dg/cpp1z/attributes-enum-1a.C
+++ b/gcc/testsuite/g++.dg/cpp1z/attributes-enum-1a.C
@@ -1,4 +1,5 @@
-// This macro should not be defined without -std=c++17.
+// { dg-do compile { target c++14_down } }
+// This macro should not be defined without c++17.
#ifdef __cpp_enumerator_attributes
#error __cpp_enumerator_attributes defined
diff --git a/gcc/testsuite/g++.dg/cpp1z/fold7a.C
b/gcc/testsuite/g++.dg/cpp1z/fold7a.C
index 5c782ff0969..8cca8792709 100644
--- a/gcc/testsuite/g++.dg/cpp1z/fold7a.C
+++ b/gcc/testsuite/g++.dg/cpp1z/fold7a.C
@@ -1,4 +1,5 @@
-// This macro should not be defined without -std=c++17.
+// { dg-do compile { target c++14_down } }
+// This macro should not be defined without c++17.
#ifdef __cpp_fold_expressions
#error __cpp_fold_expressions defined
diff --git a/gcc/testsuite/g++.dg/cpp1z/nontype3a.C
b/gcc/testsuite/g++.dg/cpp1z/nontype3a.C
index a704e5045b6..b3ffe037904 100644
--- a/gcc/testsuite/g++.dg/cpp1z/nontype3a.C
+++ b/gcc/testsuite/g++.dg/cpp1z/nontype3a.C
@@ -1,4 +1,5 @@
-// This macro should not be defined without -std=c++17.
+// { dg-do compile { target c++14_down } }
+// This macro should not be defined without c++17.
#ifdef __cpp_nontype_template_args
#error __cpp_nontype_template_args defined
diff --git a/gcc/testsuite/g++.dg/cpp1z/utf8-2a.C
b/gcc/testsuite/g++.dg/cpp1z/utf8-2a.C
index 0e243d68a75..b2a99a99023 100644
--- a/gcc/testsuite/g++.dg/cpp1z/utf8-2a.C
+++ b/gcc/testsuite/g++.dg/cpp1z/utf8-2a.C
@@ -1,4 +1,5 @@
-// This macro should not be 201411 without -std=c++17.
+// { dg-do compile { target c++14_down } }
+// This macro should not be 201411 without c++17.
#if __cpp_unicode_characters == 201411
#error Wrong value for __cpp_unicode_characters
diff --git a/gcc/testsuite/g++.dg/parse/error11.C
b/gcc/testsuite/g++.dg/parse/error11.C
index 1a49d6edb12..4baf97e531d 100644
--- a/gcc/testsuite/g++.dg/parse/error11.C
+++ b/gcc/testsuite/g++.dg/parse/error11.C
@@ -1,5 +1,5 @@
// { dg-do compile }
-// { dg-options "-fshow-column" }"
+// { dg-options "-fshow-column" }
// Origin: Giovanni Bajo <giovannibajo at gcc dot gnu dot org>
// Try to find out when the digraph '<:' is used as a mistake, and parse it
// correctly to avoid cascaded errors.
@@ -50,12 +50,16 @@ void func(void)
// the special error message.
Foo<: :B> k2; // { dg-bogus "cannot begin|alternate spelling" "smart
error should not be triggered here" }
Foo[:B> k1; // { dg-bogus "cannot begin|alternate spelling" "smart
error should not be triggered here" }
-// { dg-error "6:missing template arguments before" "template" { target *-*-*
} 51 }
-// { dg-error "9:expected primary-expression before ':' token" "primary" {
target *-*-* } 51 }
-// { dg-error "8:expected '\]' before ':' token" "backslash" { target *-*-* }
51 }
-// { dg-error "6:missing template arguments before" "template" { target *-*-*
} 52 }
-// { dg-error "7:expected primary-expression before ':' token" "primary" {
target *-*-* } 52 }
-// { dg-error "7:expected '\]' before ':' token" "backslash" { target *-*-* }
52 }
+// { dg-error "6:missing template arguments before" "template" { target
c++14_down } .-2 }
+// { dg-error "9:expected primary-expression before ':' token" "primary" {
target c++14_down } .-3 }
+// { dg-error "8:expected '\]' before ':' token" "backslash" { target
c++14_down } .-4 }
+// { dg-error "6:missing template arguments before" "template" { target
c++14_down } .-4 }
+// { dg-error "7:expected primary-expression before ':' token" "primary" {
target c++14_down } .-5 }
+// { dg-error "7:expected '\]' before ':' token" "backslash" { target
c++14_down } .-6 }
+// { dg-error "9:expected identifier" "" { target c++17 } .-8 }
+// { dg-error "8:expected" "" { target c++17 } .-9 }
+// { dg-error "7:expected identifier" "" { target c++17 } .-9 }
+// { dg-error "7:expected" "" { target c++17 } .-10 }
//
int Foo[2];
Foo[::value] = 0;
diff --git a/gcc/testsuite/g++.dg/torture/pr34850.C
b/gcc/testsuite/g++.dg/torture/pr34850.C
index c4d808c5a0d..59dd5dfde7d 100644
--- a/gcc/testsuite/g++.dg/torture/pr34850.C
+++ b/gcc/testsuite/g++.dg/torture/pr34850.C
@@ -1,6 +1,6 @@
/* { dg-do compile } */
/* { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
-/* { dg-options "-ffat-lto-objects -Wno-return-type" } */
+/* { dg-options "-ffat-lto-objects -Wno-return-type -Wno-attribute-warning" }
*/
typedef unsigned char uint8_t;
typedef unsigned int uint32_t;
diff --git a/gcc/testsuite/g++.dg/torture/pr49394.C
b/gcc/testsuite/g++.dg/torture/pr49394.C
index 7bd8fd4dc72..75901a5d668 100644
--- a/gcc/testsuite/g++.dg/torture/pr49394.C
+++ b/gcc/testsuite/g++.dg/torture/pr49394.C
@@ -7,6 +7,8 @@ struct Mutex
~Mutex ()
#if __cplusplus <= 201402L
throw(int) // { dg-warning "deprecated" "" { target {
c++11 && { ! c++17 } } } }
+#else
+ noexcept(false)
#endif
{
if (locked)
diff --git a/gcc/testsuite/g++.dg/torture/pr82154.C
b/gcc/testsuite/g++.dg/torture/pr82154.C
index e229c3e640e..698340d8c65 100644
--- a/gcc/testsuite/g++.dg/torture/pr82154.C
+++ b/gcc/testsuite/g++.dg/torture/pr82154.C
@@ -1,5 +1,6 @@
// { dg-do compile }
-// { dg-additional-options "-Wno-deprecated" }
+// { dg-additional-options "-std=c++14 -Wno-deprecated" }
+// C++17 does not allow dynamic exception specification.
namespace a {
int b;
diff --git a/gcc/testsuite/g++.dg/ubsan/pr85029.C
b/gcc/testsuite/g++.dg/ubsan/pr85029.C
index 07472af16a5..836ce69cc15 100644
--- a/gcc/testsuite/g++.dg/ubsan/pr85029.C
+++ b/gcc/testsuite/g++.dg/ubsan/pr85029.C
@@ -1,7 +1,7 @@
// PR sanitizer/85029
// { dg-do compile }
// { dg-skip-if "" { *-*-* } { "-flto -fno-fat-lto-objects" } }
-// { dg-options "-fsanitize=undefined" }
+// { dg-options "-fsanitize=undefined -Wno-register" }
struct B {
virtual B bar ();
diff --git a/gcc/testsuite/g++.dg/ubsan/vptr-12.C
b/gcc/testsuite/g++.dg/ubsan/vptr-12.C
index f23bbc3fd10..79d4290754e 100644
--- a/gcc/testsuite/g++.dg/ubsan/vptr-12.C
+++ b/gcc/testsuite/g++.dg/ubsan/vptr-12.C
@@ -1,6 +1,7 @@
// { dg-do run }
// { dg-shouldfail "ubsan" }
-// { dg-options "-fsanitize=vptr -fno-sanitize-recover=vptr" }
+// { dg-options "-fsanitize=vptr -fno-sanitize-recover=vptr
-fstrong-eval-order=some" }
+// FIXME: See PR95221 for why we use a specific eval order.
struct MyClass
{
@@ -18,5 +19,5 @@ main ()
return 0;
}
-// { dg-output "\[^\n\r]*vptr-12.C:16:\[0-9]*: runtime error: member call on
address 0x\[0-9a-fA-F]* which does not point to an object of type
'MyClass'(\n|\r\n|\r)" }
+// { dg-output "\[^\n\r]*vptr-12.C:17:\[0-9]*: runtime error: member call on
address 0x\[0-9a-fA-F]* which does not point to an object of type
'MyClass'(\n|\r\n|\r)" }
// { dg-output "0x\[0-9a-fA-F]*: note: object has invalid vptr" }
diff --git a/gcc/testsuite/lib/target-supports.exp
b/gcc/testsuite/lib/target-supports.exp
index b335108358d..58638a3e189 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -9046,7 +9046,7 @@ proc check_effective_target_c++ { } {
return 0
}
-set cxx_default "c++14"
+set cxx_default "c++17"
# Check whether the current active language standard supports the features
# of C++11/C++14 by checking for the presence of one of the -std flags.
# This assumes that the default for the compiler is $cxx_default, and that
diff --git a/gcc/testsuite/obj-c++.dg/try-catch-9.mm
b/gcc/testsuite/obj-c++.dg/try-catch-9.mm
index 73c7c991709..b2dc61b9989 100644
--- a/gcc/testsuite/obj-c++.dg/try-catch-9.mm
+++ b/gcc/testsuite/obj-c++.dg/try-catch-9.mm
@@ -6,7 +6,7 @@
/* { dg-xfail-run-if "PR23616" { *-*-* } { "-fgnu-runtime" } {
"-fnext-runtime" } } */
/* { dg-xfail-if "Needs OBJC2 ABI" { *-*-darwin* && { lp64 && { ! objc2 } } }
{ "-fnext-runtime" "-fgnu-runtime" } { "" } }
/* { dg-prune-output ".*internal compiler error.*" } */
-/* { dg-options "-fobjc-exceptions -O2" } */
+/* { dg-options "-fobjc-exceptions -O2 -Wno-register" } */
#include "../objc-obj-c++-shared/TestsuiteObject.m"
#include <stdlib.h>
diff --git a/libgomp/testsuite/libgomp.c++/atomic-3.C
b/libgomp/testsuite/libgomp.c++/atomic-3.C
index f957b2fece5..c02532d3206 100644
--- a/libgomp/testsuite/libgomp.c++/atomic-3.C
+++ b/libgomp/testsuite/libgomp.c++/atomic-3.C
@@ -1,5 +1,6 @@
// { dg-do run }
-// { dg-options "-Wno-deprecated" }
+// C++17 forbids ++ on bool.
+// { dg-options "-Wno-deprecated -std=gnu++14" }
extern "C" void abort (void);
bool v, x1, x2, x3, x4, x5, x6;
base-commit: a2d196e75cef95c2b70734ad02e94f9da0e769fe
--
Marek Polacek • Red Hat, Inc. • 300 A St, Boston, MA
