[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715
--- Comment #19 from CVS Commits ---
The trunk branch has been updated by Marek Polacek :
https://gcc.gnu.org/g:3abcbf243239f9576a60f4ce7f8ee4b3fa14784b
commit r12-6802-g3abcbf243239f9576a60f4ce7f8ee4b3fa14784b
Author: Marek Polacek
Date: Fri Jan 14 17:41:49 2022 -0500
c++: ICE with noexcept and canonical types [PR101715]
This is a "canonical types differ for identical types" ICE, which started
with r11-4682. It's a bit tricky to explain. Consider:
template struct S {
S bar() noexcept(T::value); // #1
S foo() noexcept(T::value); // #2
};
template S S::foo() noexcept(T::value) {} // #3
We ICE because #3 and #2 have the same type, but their canonical types
differ: TYPE_CANONICAL (#3) == #2 but TYPE_CANONICAL (#2) == #1.
The member functions #1 and #2 have the same type. However, since their
noexcept-specifier is deferred, when parsing them, we create a variant for
both of them, because DEFERRED_PARSE cannot be compared. In other words,
build_cp_fntype_variant's
tree v = TYPE_MAIN_VARIANT (type);
for (; v; v = TYPE_NEXT_VARIANT (v))
if (cp_check_qualified_type (v, type, type_quals, rqual, raises, late))
return v;
will *not* find an existing variant when creating a method_type for #2, so
we
have to create a new one.
But then we perform delayed parsing and call
fixup_deferred_exception_variants
for #1 and #2. f_d_e_v will replace TYPE_RAISES_EXCEPTIONS with the newly
parsed noexcept-specifier. It also sets TYPE_CANONICAL (#2) to #1. Both
noexcepts turned out to be the same, so now we have two equivalent variants
in
the list! I.e.,
+-+ +-+ +-+
| main | | #2 | | #1 |
| S S::(S*) |->| S S::(S*) |->| S S::(S*)
|->NULL
|-| | noex(T::value) | | noex(T::value) |
+-+ +-+ +-+
Then we get to #3. As for #1 and #2, grokdeclarator calls
build_memfn_type,
which ends up calling build_cp_fntype_variant, which will use the loop
above to look for an existing variant. The first one that matches
cp_check_qualified_type will be used, so we use #2 rather than #1, and the
TYPE_CANONICAL mismatch follows. Hopefully that makes sense.
As for the fix, I didn't think I could rewrite the method_type #2 with #1
because the type may have escaped via decltype. So my approach is to
elide #2 from the list, so when looking for a matching variant, we always
find #1 (#2 remains live though, which admittedly sounds sort of dodgy).
PR c++/101715
gcc/cp/ChangeLog:
* tree.cc (fixup_deferred_exception_variants): Remove duplicate
variants after parsing the exception specifications.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/noexcept72.C: New test.
* g++.dg/cpp0x/noexcept73.C: New test.
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715 --- Comment #18 from Sergei Trofimovich --- (In reply to Marek Polacek from comment #17) > Patch posted > https://gcc.gnu.org/pipermail/gcc-patches/2022-January/588520.html Applying patch locally fixes build of compiler-rt from llvm-13 for me. Thank you!
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715 Marek Polacek changed: What|Removed |Added Keywords||patch --- Comment #17 from Marek Polacek --- Patch posted https://gcc.gnu.org/pipermail/gcc-patches/2022-January/588520.html
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715
--- Comment #16 from Marek Polacek ---
This slightly modified test started to ICE with r11-4682 which is the gist of
the problem:
template struct S {
S bar() noexcept(T::value);
S foo() noexcept(T::value);
};
template S S::foo() noexcept(T::value) {}
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715
--- Comment #15 from Sergei Trofimovich ---
clang's compiler-rt fails to build for quite a while due to this ICE.
Trying to poke at the failure. I shrunk the example slightly further:
template struct S {
S & bar() noexcept(A::value);
S & foo() noexcept(A::value);
};
template S & S::foo() noexcept(A::value) {}
c++17 seems to be the trigger (perhaps due to noexcept argument type change?).
Also, if we comment out seemingly unrelated `S::foo()` declaration ICE
disappears. Could it be that there is an unexpected type sharing in an
uninstantiated type?
The backtrace:
$ g++-12.0.0 -c a.c.cpp -std=c++14
$ g++-12.0.0 -c a.c.cpp -std=c++17
a.c.cpp:6:56: internal compiler error: canonical types differ for identical
types 'S& (S::)() noexcept (A::value)' and 'S& (S::)() noexcept
(A::value)'
6 | template S & S::foo() noexcept(A::value) {}
|^
0xc3f6ee comptypes(tree_node*, tree_node*, int)
../../gcc-12-20211226/gcc/cp/typeck.c:1558
0xa784ce duplicate_decls(tree_node*, tree_node*, bool, bool)
../../gcc-12-20211226/gcc/cp/decl.c:2409
0xa7f2bb grokfndecl
../../gcc-12-20211226/gcc/cp/decl.c:10351
0xa83cf6 grokdeclarator(cp_declarator const*, cp_decl_specifier_seq*,
decl_context, int, tree_node**)
../../gcc-12-20211226/gcc/cp/decl.c:14154
0xa88196 start_function(cp_decl_specifier_seq*, cp_declarator const*,
tree_node*)
../../gcc-12-20211226/gcc/cp/decl.c:17171
0xb82c0f cp_parser_function_definition_from_specifiers_and_declarator
../../gcc-12-20211226/gcc/cp/parser.c:31047
0xb82c0f cp_parser_init_declarator
../../gcc-12-20211226/gcc/cp/parser.c:22520
0xb8a93e cp_parser_single_declaration
../../gcc-12-20211226/gcc/cp/parser.c:31683
0xb8aab6 cp_parser_template_declaration_after_parameters
../../gcc-12-20211226/gcc/cp/parser.c:31243
0xb8b340 cp_parser_explicit_template_declaration
../../gcc-12-20211226/gcc/cp/parser.c:31509
0xb8dcf1 cp_parser_declaration
../../gcc-12-20211226/gcc/cp/parser.c:14849
0xb8e7a2 cp_parser_toplevel_declaration
../../gcc-12-20211226/gcc/cp/parser.c:14939
0xb8e7a2 cp_parser_translation_unit
../../gcc-12-20211226/gcc/cp/parser.c:4987
0xb8e7a2 c_parse_file()
../../gcc-12-20211226/gcc/cp/parser.c:47944
0xcbefcd c_common_parse_file()
../../gcc-12-20211226/gcc/c-family/c-opts.c:1238
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715 Andrew Pinski changed: What|Removed |Added CC||pjfloyd at wanadoo dot fr --- Comment #14 from Andrew Pinski --- *** Bug 103516 has been marked as a duplicate of this bug. ***
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715 Andrew Pinski changed: What|Removed |Added CC||slyfox at gcc dot gnu.org --- Comment #13 from Andrew Pinski --- *** Bug 103279 has been marked as a duplicate of this bug. ***
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715 --- Comment #12 from Marek Polacek --- OK, I'd totally forgotten about this PR.
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715 --- Comment #11 from Martin Liška --- @Marek: Can you please take a look?
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715 Andrew Pinski changed: What|Removed |Added CC||marxin at gcc dot gnu.org --- Comment #10 from Andrew Pinski --- *** Bug 103078 has been marked as a duplicate of this bug. ***
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715 Marek Polacek changed: What|Removed |Added Assignee|unassigned at gcc dot gnu.org |mpolacek at gcc dot gnu.org Status|NEW |ASSIGNED
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715 --- Comment #9 from Jonathan Wakely --- Bisection shows the ICE starts at r12-1822, which was backported as r11-8662
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types caused by r12-1824
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715 Richard Biener changed: What|Removed |Added Target Milestone|--- |11.3 Priority|P3 |P2 Known to work||10.3.1
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types caused by r12-1824
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715 --- Comment #8 from Andrew Pinski --- (In reply to H.J. Lu from comment #7) > It is caused by r12-1824. It can't be as it was not backported to GCC 11.
[Bug c++/101715] [11/12 Regression] ICE with noexcept and canonical types differ for identical types caused by r12-1824
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101715 H.J. Lu changed: What|Removed |Added Summary|[11/12 Regression] ICE with |[11/12 Regression] ICE with |noexcept and canonical |noexcept and canonical |types differ for identical |types differ for identical |types |types caused by r12-1824 CC||pinskia at gcc dot gnu.org --- Comment #7 from H.J. Lu --- It is caused by r12-1824.
