[Bug c++/109283] Destructor of co_yield conditional argument called twice
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109283 --- Comment #3 from ncm at cantrip dot org --- Appears fixed in 13.1 Still ICEs in trunk, Compiler-Explorer-Build-gcc-70d038235cc91ef1ea4fce519e628cfb2d297bff-binutils-2.40) 14.0.0 20230508 (experimental): : In function 'std::generator > source(int&, std::string)': :513:1: internal compiler error: in flatten_await_stmt, at cp/coroutines.cc:2899 513 | }
[Bug c++/59498] [DR 1430][10/11/12/13 Regression] Pack expansion error in template alias
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59498 --- Comment #22 from ncm at cantrip dot org --- CWG 1430 seems to be about disallowing a construct that requires capturing an alias declaration into a name mangling. This bug and at least some of those referred to it do not ask for any such action.
[Bug c++/109283] Destructor of co_yield conditional argument called twice
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109283 --- Comment #2 from ncm at cantrip dot org --- Betting this one is fixed by deleting code.
[Bug c++/109291] type alias template rejects pack
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109291 --- Comment #2 from ncm at cantrip dot org --- CWG 1430 is still marked Open, and is anyway only superficially analogous. Here, there is no need for an alias to be encoded into a type signature.
[Bug c++/109291] New: type alias template rejects pack
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109291
Bug ID: 109291
Summary: type alias template rejects pack
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ncm at cantrip dot org
Target Milestone: ---
template
struct type_identity { using type = T; };
template
using type_identity_t = typename type_identity::type;
template
struct S1 { using alias1 = typename type_identity::type; };
template
struct S2 { using alias2 = typename type_identity_t; };
int main() {
S1::alias1 a; // OK
S2::alias2 b; // Fails
}
// Here, alias1 is fine, but alias2, the same type, is not.
// MSVC accepts both declarations. Clang matches Gcc.
// error: pack expansion argument for non-pack parameter âTâ of alias template
// error: expected nested-name-specifier
[Bug c++/109283] New: Destructor of co_yield conditional argument called twice
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109283 Bug ID: 109283 Summary: Destructor of co_yield conditional argument called twice Product: gcc Version: 12.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: ncm at cantrip dot org Target Milestone: --- Created attachment 54754 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54754&action=edit Reproducer Basically: co_yield a ? s : t; segfaults, if (a) co_yield s; else co_yield t; does not. The segfault traces to s/t's destructor being called twice. Full reproducer attached, relying on Casey Carter's generator implementation, pasted in. This may be related to 101367. Compiled with gcc-12.2, this program segfaults. Compiled with gcc-trunk or gcc-coroutines on Godbolt, identified as: g++ (Compiler-Explorer-Build-gcc-13ec81eb4c3b484ad636000fa8f6d925e15fb983-binutils-2.38) 13.0.1 20230325 (experimental) the compiler ICEs: :513:1: internal compiler error: in flatten_await_stmt, at cp/coroutines.cc:2899 513 | }
[Bug c++/68703] __attribute__((vector_size(N))) template member confusion
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68703 --- Comment #10 from ncm at cantrip dot org --- (In reply to ncm from comment #9) > This bug appears not to manifest in g++-8, 9, and 10. Of the three code samples in comment 4, the first and third fail to compile because N is undefined. What code was intended there? It seems like we should check the corrected versions of those before declaring this fixed. The code sample in example 3 still reports failings in g++-10.2.
[Bug target/87085] with -march=i386, gcc should not generate code including endbr instruction
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87085 ncm at cantrip dot org changed: What|Removed |Added CC||ncm at cantrip dot org --- Comment #8 from ncm at cantrip dot org --- (In reply to H.J. Lu from comment #7) > (In reply to chengming from comment #4) > > Created attachment 44602 [details] > > ELF file > > > > compiled with command > > gcc -v -save-temps -m32 -march=i386 -fcf-protection=none -o onlyReturn > > onlyReturn.c > output.txt 2>&1 > > Fedora 28 run-time only supports i686 or above. You can't use any libraries > on Fedora 28. Not relevant: Reporter is not trying to run i386 code on fedora 28, but only generate i386 code to run on a cross target.
[Bug tree-optimization/97736] [9/10/11 Regression] switch codegen
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97736 --- Comment #12 from ncm at cantrip dot org --- As it is, your probability of failure in 9 and 10 is exactly 1.0.
[Bug tree-optimization/97736] [9/10/11 Regression] switch codegen
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97736 --- Comment #10 from ncm at cantrip dot org --- Don't understand, the compiler we are using (9) has the regression. It looks like a trivial backport.
[Bug libstdc++/42857] std::istream::ignore(std::streamsize n) calls unnecessary underflow
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42857 --- Comment #9 from ncm at cantrip dot org --- (In reply to Jonathan Wakely from comment #8) > Probably changed by one of the patches for PR 94749 or PR 96161, although I > still see two reads for the first example. Thank you, I was mistaken. This bug is still present in g++-10.
[Bug c++/68703] __attribute__((vector_size(N))) template member confusion
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68703 --- Comment #9 from ncm at cantrip dot org --- This bug appears not to manifest in g++-8, 9, and 10.
[Bug c++/66028] false positive, unused loop variable
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66028 --- Comment #2 from ncm at cantrip dot org --- This bug appears not to manifest in g++-10.2.
[Bug libstdc++/42857] std::istream::ignore(std::streamsize n) calls unnecessary underflow
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42857 --- Comment #7 from ncm at cantrip dot org --- This bug appears not to manifest in g++-10.
[Bug c++/58855] Attributes ignored on type alias in template
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58855 --- Comment #2 from ncm at cantrip dot org --- This bug is still present in g++-10.2
[Bug tree-optimization/97736] [9/10/11 Regression] switch codegen
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97736 --- Comment #6 from ncm at cantrip dot org --- The referenced patch seems to have also deleted a fair bit of explanatory comment text, including a list of possible refinements for selected targets.
[Bug target/97736] New: [9/10 Regression] switch codegen
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97736
Bug ID: 97736
Summary: [9/10 Regression] switch codegen
Product: gcc
Version: 9.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: ncm at cantrip dot org
Target Milestone: ---
In Gcc 8 and previous, the following code
bool is_vowel(char c) {
switch (c)
case'a':case'e':case'i':case'o':case'u':
return true;
return false;
}
compiled with -O2 or better, for numerous x86-64 targets,
resolves to a bitwise flag check, e.g.
lea ecx, [rdi-97]
xor eax, eax
cmp cl, 20
ja .L1
mov eax, 1
sal rax, cl
testeax, 1065233
setne al
.L1:
ret
Starting in gcc-9, this optimization is not performed
anymore at -O2 for many common targets (e.g. -march=skylake),
and we get
sub edi, 97
cmp dil, 20
ja .L2
movzx edi, dil
jmp [QWORD PTR .L4[0+rdi*8]]
.L4:
.quad .L5
.quad .L2
.quad .L2
.quad .L2
.quad .L5
.quad .L2
.quad .L2
.quad .L2
.quad .L5
.quad .L2
.quad .L2
.quad .L2
.quad .L2
.quad .L2
.quad .L5
.quad .L2
.quad .L2
.quad .L2
.quad .L2
.quad .L2
.quad .L5
.L2:
mov eax, 0
ret
.L5:
mov eax, 1
ret
same as with -O0 or -O1.
