Re: Support 'UNSUPPORTED: [...]: exception handling disabled' for libstdc++ testing (was: Support in the GCC(/C++) test suites for '-fno-exceptions')

[Jonathan Wakely <jwakely@redhat.com>]

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On Wed, 7 Jun 2023 at 10:08, Thomas Schwinge <thomas@codesourcery.com>
wrote:

> Hi!
>
> On 2023-06-07T09:12:31+0100, Jonathan Wakely <jwakely@redhat.com> wrote:
> > On Wed, 7 Jun 2023 at 08:13, Thomas Schwinge wrote:
> >> On 2023-06-06T20:31:21+0100, Jonathan Wakely <jwakely@redhat.com>
> wrote:
> >> > On Tue, 6 Jun 2023 at 20:14, Thomas Schwinge <thomas@codesourcery.com
> >
> >> > wrote:
> >> >> This issue comes up in context of me working on C++ support for GCN
> and
> >> >> nvptx target.  Those targets shall default to '-fno-exceptions' --
> or,
> >> >> "in other words", '-fexceptions' is not supported.  (Details omitted
> >> >> here.)
> >> >>
> >> >> It did seem clear to me that with such a configuration it'll be hard
> to
> >> >> get clean test results.  Then I found code in
> >> >> 'gcc/testsuite/lib/gcc-dg.exp:gcc-dg-prune':
> >> >>
> >> >>     # If exceptions are disabled, mark tests expecting exceptions to
> be
> >> >> enabled
> >> >>     # as unsupported.
> >> >>     if { ![check_effective_target_exceptions_enabled] } {
> >> >>         if [regexp "(^|\n)\[^\n\]*: error: exception handling
> disabled"
> >> >> $text] {
> >> >>             return "::unsupported::exception handling disabled"
> >> >>         }
> >> >>
> >> >> ..., which, in a way, sounds as if the test suite generally is meant
> to
> >> >> produce useful results for '-fno-exceptions', nice surprise!
> >> >>
> >> >> Running x86_64-pc-linux-gnu (not yet GCN, nvptx) 'make check' with:
> >> >>
> >> >>     RUNTESTFLAGS='--target_board=unix/-fno-exceptions\{,-m32\}'
> >> >>
> >> >> ..., I find that indeed this does work for a lot of test cases,
> where we
> >> >> then get (random example):
> >> >>
> >> >>      PASS: g++.dg/coroutines/pr99710.C  (test for errors, line 23)
> >> >>     -PASS: g++.dg/coroutines/pr99710.C (test for excess errors)
> >> >>     +UNSUPPORTED: g++.dg/coroutines/pr99710.C: exception handling
> >> disabled
> >> >>
> >> >> ..., due to:
> >> >>
> >> >>      [...]/g++.dg/coroutines/pr99710.C: In function 'task my_coro()':
> >> >>     +[...]/g++.dg/coroutines/pr99710.C:18:10: error: exception
> handling
> >> >> disabled, use '-fexceptions' to enable
> >> >>      [...]/g++.dg/coroutines/pr99710.C:23:7: error: await expressions
> >> are
> >> >> not permitted in handlers
> >> >>      compiler exited with status 1
> >> >>
> >> >> But, we're nowhere near clean test results: PASS -> FAIL as well as
> >> >> XFAIL -> XPASS regressions, due to 'error: exception handling
> disabled'
> >> >> precluding other diagnostics seems to be one major issue.
> >> >>
> >> >> Is there interest in me producing the obvious (?) changes to those
> test
> >> >> cases, such that compiler g++ as well as target library libstdc++
> test
> >> >> results are reasonably clean?  (If you think that's all "wasted
> effort",
> >> >> then I suppose I'll just locally ignore any FAILs/XPASSes/UNRESOLVEDs
> >> >> that appear in combination with
> >> >> 'UNSUPPORTED: [...]: exception handling disabled'.)
> >> >
> >> > I would welcome that for libstdc++.
> >>
> >> Assuming no issues found in testing, OK to push the attached
> >> "Support 'UNSUPPORTED: [...]: exception handling disabled' for libstdc++
> >> testing"?
> >> (Thanks, Jozef!)
> >
> > Yes please.
>
> Pushed commit r14-1604-g5faaabef3819434d13fcbf749bd07bfc98ca7c3c
> "Support 'UNSUPPORTED: [...]: exception handling disabled' for libstdc++
> testing"
> to master branch, as posted.
>
> For one-week-old GCC commit 2720bbd597f56742a17119dfe80edc2ba86af255,
> x86_64-pc-linux-gnu, I see no changes without '-fno-exceptions' (as
> expected), and otherwise:
>
>                     === libstdc++ Summary for
> [-unix-]{+unix/-fno-exceptions+} ===
>
>     # of expected passes            [-15044-]{+12877+}
>     # of unexpected failures        [-5-]{+10+}
>     # of expected failures          [-106-]{+77+}
>     {+# of unresolved testcases     6+}
>     # of unsupported tests          [-747-]{+1846+}
>
> As expected, there's a good number of (random example):
>
>     -PASS: 18_support/105387.cc (test for excess errors)
>     -PASS: 18_support/105387.cc execution test
>     +UNSUPPORTED: 18_support/105387.cc: exception handling disabled
>
> ..., plus the following:
>
>     [-PASS:-]{+FAIL:+} 23_containers/vector/capacity/constexpr.cc (test
> for excess errors)
>
>
> [...]/libstdc++-v3/testsuite/23_containers/vector/capacity/constexpr.cc:101:
> error: non-constant condition for static assertion
>     In file included from
> [...]/libstdc++-v3/testsuite/23_containers/vector/capacity/constexpr.cc:6:
>
> [...]/libstdc++-v3/testsuite/23_containers/vector/capacity/constexpr.cc:101:
>  in 'constexpr' expansion of 'test_shrink_to_fit()'
>     [...]/libstdc++-v3/testsuite/util/testsuite_hooks.h:56: error:
> '__builtin_fprintf(stderr, ((const char*)"%s:%d: %s: Assertion \'%s\'
> failed.\012"), ((const
> char*)"[...]/libstdc++-v3/testsuite/23_containers/vector/capacity/constexpr.cc"),
> 92, ((const char*)"constexpr bool test_shrink_to_fit()"), ((const
> char*)"v.capacity() == 0"))' is not a constant expression
>     [...]/libstdc++-v3/testsuite/util/testsuite_hooks.h:66: note: in
> expansion of macro '_VERIFY_PRINT'
>
> [...]/libstdc++-v3/testsuite/23_containers/vector/capacity/constexpr.cc:92:
> note: in expansion of macro 'VERIFY'
>     compiler exited with status 1
>
> ..., and:
>
>     PASS: 23_containers/vector/capacity/shrink_to_fit.cc (test for excess
> errors)
>     [-PASS:-]{+FAIL:+} 23_containers/vector/capacity/shrink_to_fit.cc
> execution test
>
>
> [...]/libstdc++-v3/testsuite/23_containers/vector/capacity/shrink_to_fit.cc:33:
> void test01(): Assertion 'v.size() == v.capacity()' failed.
>
> ..., and:
>
>     PASS: 27_io/basic_ostream/inserters_arithmetic/pod/23875.cc (test for
> excess errors)
>     [-PASS:-]{+FAIL:+}
> 27_io/basic_ostream/inserters_arithmetic/pod/23875.cc execution test
>
>     terminate called after throwing an instance of 'std::bad_cast'
>       what():  std::bad_cast
>
> ..., and:
>
>     [-PASS:-]{+FAIL:+} ext/bitmap_allocator/check_allocate_max_size.cc
> (test for excess errors)
>     [-PASS:-]{+UNRESOLVED:+}
> ext/bitmap_allocator/check_allocate_max_size.cc [-execution
> test-]{+compilation failed to produce executable+}
>
>
> [...]/libstdc++-v3/testsuite/ext/bitmap_allocator/check_allocate_max_size.cc:
> In function 'int main()':
>
> [...]/libstdc++-v3/testsuite/ext/bitmap_allocator/check_allocate_max_size.cc:29:
> error: 'check_allocate_max_size' is not a member of '__gnu_test'
>
> [...]/libstdc++-v3/testsuite/ext/bitmap_allocator/check_allocate_max_size.cc:29:
> error: expected primary-expression before '>' token
>
> [...]/libstdc++-v3/testsuite/ext/bitmap_allocator/check_allocate_max_size.cc:29:
> error: expected primary-expression before ')' token
>
> ..., and similarly:
>
>     [-PASS:-]{+FAIL:+} ext/malloc_allocator/check_allocate_max_size.cc
> (test for excess errors)
>     [-PASS:-]{+UNRESOLVED:+}
> ext/malloc_allocator/check_allocate_max_size.cc [-execution
> test-]{+compilation failed to produce executable+}
>
>     [-PASS:-]{+FAIL:+} ext/mt_allocator/check_allocate_max_size.cc (test
> for excess errors)
>     [-PASS:-]{+UNRESOLVED:+} ext/mt_allocator/check_allocate_max_size.cc
> [-execution test-]{+compilation failed to produce executable+}
>
>     [-PASS:-]{+FAIL:+} ext/new_allocator/check_allocate_max_size.cc (test
> for excess errors)
>     [-PASS:-]{+UNRESOLVED:+} ext/new_allocator/check_allocate_max_size.cc
> [-execution test-]{+compilation failed to produce executable+}
>
>     [-PASS:-]{+FAIL:+} ext/pool_allocator/check_allocate_max_size.cc (test
> for excess errors)
>     [-PASS:-]{+UNRESOLVED:+} ext/pool_allocator/check_allocate_max_size.cc
> [-execution test-]{+compilation failed to produce executable+}
>
>     [-PASS:-]{+FAIL:+} ext/throw_allocator/check_allocate_max_size.cc
> (test for excess errors)
>     [-PASS:-]{+UNRESOLVED:+}
> ext/throw_allocator/check_allocate_max_size.cc [-execution
> test-]{+compilation failed to produce executable+}
>
> That's all!  :-)
>
> Given my limited C++ language and libstdc++ implementation skills, it's
> probably more effective if you address these?  But I'll of course give it
> a try if you'd like me to.
>

Yes, I'll fix those, thanks for the heads up.