Parser crash when template argument is missing from designated initializer list for a union of structs #67173

cogwheel · 2023-09-22T18:21:23Z

The following invalid code compiled with -std=c++2b causes the parser to crash in clang++ 17 and 18, but not 16. Here's a live example.

template <class T>
union Vec2d {
    struct { T x; T y; };
};

template <class T>
constexpr Vec2d<T> operator+(Vec2d<T> const a, Vec2d<T> const b) {
    // Change to `Vec2d<T>` to fix the code
    return Vec2d{.x = a.x + b.x, .y = a.y + b.y};
}

int main() {
    Vec2d<int> foo{};
    Vec2d<int> bar{.x = 5, .y = 10};
    return (foo + bar).x;
}

The text was updated successfully, but these errors were encountered:

shafik · 2023-09-22T19:58:48Z

I reduced this a bunch to remove things not involved: https://godbolt.org/z/YceqcxosP

template <class T>
union Vec2d {
    struct { T x; };
};

Vec2d<int> f(Vec2d<int> const a) {
    // Change to `Vec2d<int>` to fix the code
    return Vec2d{.x = a.x + a.x};
}

void g() {
    f(Vec2d<int>{});
}

Assertion:

clang++: /root/llvm-project/clang/lib/Sema/SemaInit.cpp:1449:
void {anonymous}::InitListChecker::CheckSubElementType(const clang::InitializedEntity&, clang::InitListExpr*, clang::QualType, unsigned int&, clang::InitListExpr*, unsigned int&, bool):
Assertion `AggrDeductionCandidateParamTypes' failed.

Backtrace:

PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 <source>
1.	<source>:8:33: current parser token ';'
2.	<source>:6:34: parsing function body 'f'
3.	<source>:6:34: in compound statement ('{}')
 #0 0x00000000036e2ff8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x36e2ff8)
 #1 0x00000000036e0cbc llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x36e0cbc)
 #2 0x000000000362a078 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f1515578420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #4 0x00007f151503b00b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #5 0x00007f151501a859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #6 0x00007f151501a729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
 #7 0x00007f151502bfd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x000000000659fb63 (anonymous namespace)::InitListChecker::CheckSubElementType(clang::InitializedEntity const&, clang::InitListExpr*, clang::QualType, unsigned int&, clang::InitListExpr*, unsigned int&, bool) SemaInit.cpp:0:0
 #9 0x00000000065a3ecd (anonymous namespace)::InitListChecker::CheckDesignatedInitializer(clang::InitializedEntity const&, clang::InitListExpr*, clang::DesignatedInitExpr*, unsigned int, clang::QualType&, clang::DeclContext::specific_decl_iterator<clang::FieldDecl>*, llvm::APSInt*, unsigned int&, clang::InitListExpr*, unsigned int&, bool, bool) SemaInit.cpp:0:0
#10 0x00000000065a4bc0 (anonymous namespace)::InitListChecker::CheckDesignatedInitializer(clang::InitializedEntity const&, clang::InitListExpr*, clang::DesignatedInitExpr*, unsigned int, clang::QualType&, clang::DeclContext::specific_decl_iterator<clang::FieldDecl>*, llvm::APSInt*, unsigned int&, clang::InitListExpr*, unsigned int&, bool, bool) SemaInit.cpp:0:0
#11 0x00000000065a4bc0 (anonymous namespace)::InitListChecker::CheckDesignatedInitializer(clang::InitializedEntity const&, clang::InitListExpr*, clang::DesignatedInitExpr*, unsigned int, clang::QualType&, clang::DeclContext::specific_decl_iterator<clang::FieldDecl>*, llvm::APSInt*, unsigned int&, clang::InitListExpr*, unsigned int&, bool, bool) SemaInit.cpp:0:0
#12 0x00000000065a1a72 (anonymous namespace)::InitListChecker::CheckStructUnionTypes(clang::InitializedEntity const&, clang::InitListExpr*, clang::QualType, llvm::iterator_range<clang::CXXBaseSpecifier const*>, clang::DeclContext::specific_decl_iterator<clang::FieldDecl>, bool, unsigned int&, clang::InitListExpr*, unsigned int&, bool) SemaInit.cpp:0:0
#13 0x000000000659fead (anonymous namespace)::InitListChecker::CheckListElementTypes(clang::InitializedEntity const&, clang::InitListExpr*, clang::QualType&, bool, unsigned int&, clang::InitListExpr*, unsigned int&, bool) (.constprop.0) SemaInit.cpp:0:0
#14 0x000000000658fffa (anonymous namespace)::InitListChecker::CheckExplicitInitList(clang::InitializedEntity const&, clang::InitListExpr*, clang::QualType&, clang::InitListExpr*, bool) (.constprop.0) SemaInit.cpp:0:0
#15 0x000000000659097e (anonymous namespace)::InitListChecker::InitListChecker(clang::Sema&, clang::InitializedEntity const&, clang::InitListExpr*, clang::QualType&, bool, bool, bool, llvm::SmallVectorImpl<clang::QualType>*) SemaInit.cpp:0:0
#16 0x0000000006598eca TryListInitialization(clang::Sema&, clang::InitializedEntity const&, clang::InitializationKind const&, clang::InitListExpr*, clang::InitializationSequence&, bool) SemaInit.cpp:0:0
#17 0x0000000006596e6b clang::InitializationSequence::InitializeFrom(clang::Sema&, clang::InitializedEntity const&, clang::InitializationKind const&, llvm::MutableArrayRef<clang::Expr*>, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6596e6b)
#18 0x00000000064b1931 clang::Sema::BuildCXXTypeConstructExpr(clang::TypeSourceInfo*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64b1931)
#19 0x000000000653cc6d clang::Sema::ActOnCXXTypeConstructExpr(clang::OpaquePtr<clang::QualType>, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x653cc6d)
#20 0x0000000005ec7846 clang::Parser::ParseCXXTypeConstructExpression(clang::DeclSpec const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ec7846)
#21 0x0000000005ea8b85 clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ea8b85)
#22 0x0000000005ea89cd clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ea89cd)
#23 0x0000000005eaa70a clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5eaa70a)
#24 0x0000000005eaa8a9 clang::Parser::ParseAssignmentExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5eaa8a9)
#25 0x0000000005eaf5a9 clang::Parser::ParseExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5eaf5a9)
#26 0x0000000005f1d2e2 clang::Parser::ParseReturnStatement() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f1d2e2)
#27 0x0000000005f205fb clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f205fb)
#28 0x0000000005f21bf8 clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f21bf8)
#29 0x0000000005f22b39 clang::Parser::ParseCompoundStatementBody(bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f22b39)
#30 0x0000000005f2445a clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f2445a)
#31 0x0000000005e51b41 clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e51b41)
#32 0x0000000005e79128 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e79128)
#33 0x0000000005e45a2b clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e45a2b)
#34 0x0000000005e4615f clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (.part.0) Parser.cpp:0:0
#35 0x0000000005e4c874 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e4c874)
#36 0x0000000005e4d09d clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e4d09d)
#37 0x0000000005e413da clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e413da)
#38 0x0000000004946658 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4946658)
#39 0x00000000041ac459 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41ac459)
#40 0x000000000412d13e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x412d13e)
#41 0x000000000428b79e clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x428b79e)
#42 0x0000000000bdb92e cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbdb92e)
#43 0x0000000000bd34ba ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#44 0x0000000003f8d929 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#45 0x000000000362a524 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x362a524)
#46 0x0000000003f8df1f clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (.part.0) Job.cpp:0:0
#47 0x0000000003f56265 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f56265)
#48 0x0000000003f56ccd clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f56ccd)
#49 0x0000000003f5ebf5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f5ebf5)
#50 0x0000000000bd909c clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbd909c)
#51 0x0000000000ad4921 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xad4921)
#52 0x00007f151501c083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#53 0x0000000000bd2f9e _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbd2f9e)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134

llvmbot · 2023-09-22T19:59:18Z

@llvm/issue-subscribers-c-20

The following invalid code compiled with `-std=c++2b` causes the parser to crash in clang++ 17 and 18, but not 16. Here's a [live example](https://godbolt.org/#z:OYLghAFBqd5TKALEBjA9gEwKYFFMCWALugE4A0BIEAZgQDbYB2AhgLbYgDkAjF%2BTXRMiAZVQtGIHgBYBQogFUAztgAKAD24AGfgCsp5eiyahUAUgBMAIUtXyKxqiIEh1ZpgDC6egFc2TKQB2cncAGQImbAA5PwAjbFIQAE5yAAd0JWIXJi9ffyC0jKyhcMiYtnjElIdsJ2yRIhZSIly/AJ5gmrqhBqaiUui4hOT7RubW/I7RvoHyyuSASnt0H1JUTi4ibDZUoy2AajMAZg9UIyUlfYAVY9wzLQBBHyZs/YA1WotMQ8CbR/2AfslERSD4nD8rNd9upjpCrvsAJ6wn4AEVh9weZkCaKOf0xjy2Oz22EOJzOLAu11uGIwTGB2HUqVI70%2BmGOHhuR1w%2B3QqQSLBIpFsEA%2BqC%2B7M53NpwP2LHILLFbJOkv20qI%2B1iCwhGMB%2BwA9Hr9h4kMZgCSSIcAGxaUXi5XU637C10dROpAkjA4HWA0jYIirJgK8W/AB0ruOKNlYcO1g1YflIYRpMjLETMchsUTWJxeOzGIxEXVbBYEQgWqxeN1tqVHkLt32gnQFbzuO9AOr7LrXI1TQr0Yj%2BwArAmkwOeFoW5WfX6A/taOh0Ome6QFmH0Y8848uEt6NxB/wAlwdOR0NwPLZbECVmsSZYjnxyERtNulgBrEAWQchixJH8ADiOP8tD/QI/ySQceGHXcuGkfg2BAQctHIQ9j1PLh%2BCUEAkKfI9t3IOBYBQT08EIQVKGoOhGFYDhuAfQRhDECROBkORhGUNRNFw8h9AsQxTTQC9rHsbBHGcVwIHcCZ2hCJhMFmIZEimdJMjEnJvDaAxlOKJh5IqYYeGE0T6jGFp1MmQzalU3pml0%2BYpmBPopIMBybIiQY9MUpYlGvdZuEJXYBVvMlzkuSUMWeV5q21f5AWBUFwQrKEYVxKEkRSyd82xdd8QefziVJU4QqpLkaSEelGWZDt7W7Xl%2BUFYUqo5es1VleVGpVFrNWih5dQNI0TRMc1FzMa12odLQnUXF03Q9LBsDbfZfX9UhAw7UNwyOFN%2B1jTN1BHZMo1HHasyy1sNyyjdHkLfZi1LctfgWxqu25Rtm1Oqd21ZTthHrWJe3Wg7h32NMxwnd6FqW2d52GnamlXZLcwuh48Og/dkOfE8z0EyFvNWdYYyOCx%2BBwnQFiWd0WBwRIy0MbhYPIeDEPRri0IwrDH2fMnyHfI4jhDS0LEte9AhkCweAsCw/yg7gjgPDHWY53ClgI5A0HQHYGASciIAwDXGESckTA6LQDJwAA3Ah1jeAhsAAdwAeT5Q86IYLZSEwiBYgx2IIiaBFaP4H3WFIBF7diXRLID8hdY4YR7aYeh/a4nBYh8YAPAkehMN4fgcGLExJGTghfTqM3sGz48GVqHwtijwsRIx%2BgCFiUg/a8HAMZBAh4JzpYaCMYAlGtu3HeYKP6NEcRJBYif2I0DH9AMowTAE6xbEMZvMMgJZeVU7OAFp7cuffgSVFFzDX6wLFifh0DL0hSAIHAt5prpVLcWSnIMsI3LmfTChUtkL%2BADtK2X/m/YyjkzLSQgT0EyYDFLTHGNA5y8Df4KSkF5HyzEdx7jlizbg0I/yWn3paaQqpl7AH2B0EMWgQw8DnPgYgZACY8AWMTTm%2BEiLq1SJrCgVAdY8L4WgShPBrRIXNpbbAw8HZO3Hq7BIHsvZcSDn7KOqiQ5hwjk4KOMdmBEHjonDGKc04Z3oFnKOedTSF2PIQEuzgy4V34FXVANcNgPnrtBY8TcW5tzmp3R%2BPc%2BB9wHkPG2six451YpPJiUhZCzxUPPLiPE%2BIrwvjYISPiX471SHvbgJ8iBn3SbYa%2Bt976P2fvALyIlLLZA/p4FB39ZIIM0kUVSwCtKqRaQZWBTBrKmTyDAmp3Q%2BloLKBgnpJlgEuX6OgjymDlh404BYXBXA0YoVvoQ9QxDSHkMNlQsRtDaGMNIiwu8KyOFKzfFIP8IZpB/mkOBQI0hxwWHuYBWQ0F6YbMxuhew7MSZ4RVhAFAhAaA0G1hPRi094nyDnpxbxSBMK8XoEisFNAiAIj5B%2BQwSKGQghYLvOpfzSBIoMKSpQ6LMXYt4hS/FrciWuHQqs9Z8tuAogIOC944SEhEJIWQihppqGWiORNM2lxtn8r2ZQ6hgQjkPkBVzd80g5V/jVYET80gVUCxAsEL5%2BDULcDZthTmqyibM0NX8xVSx76ZFcNIIAA%3D).

template &lt;class T&gt;
union Vec2d {
    struct { T x; T y; };
};

template &lt;class T&gt;
constexpr Vec2d&lt;T&gt; operator+(Vec2d&lt;T&gt; const a, Vec2d&lt;T&gt; const b) {
    // Change to `Vec2d&lt;T&gt;` to fix the code
    return Vec2d{.x = a.x + b.x, .y = a.y + b.y};
}

int main() {
    Vec2d&lt;int&gt; foo{};
    Vec2d&lt;int&gt; bar{.x = 5, .y = 10};
    return (foo + bar).x;
}

shafik · 2023-09-22T20:01:15Z

This is a regression I suspect it is related to: https://reviews.llvm.org/D139837

CC @yuanfang-chen

Also CC @Fznamznon who has looked at designated init before and may wish to look at this as well.

llvmbot · 2023-09-23T03:49:37Z

@llvm/issue-subscribers-clang-frontend

The following invalid code compiled with `-std=c++2b` causes the parser to crash in clang++ 17 and 18, but not 16. Here's a [live example](https://godbolt.org/#z:OYLghAFBqd5TKALEBjA9gEwKYFFMCWALugE4A0BIEAZgQDbYB2AhgLbYgDkAjF%2BTXRMiAZVQtGIHgBYBQogFUAztgAKAD24AGfgCsp5eiyahUAUgBMAIUtXyKxqiIEh1ZpgDC6egFc2TKQB2cncAGQImbAA5PwAjbFIQAE5yAAd0JWIXJi9ffyC0jKyhcMiYtnjElIdsJ2yRIhZSIly/AJ5gmrqhBqaiUui4hOT7RubW/I7RvoHyyuSASnt0H1JUTi4ibDZUoy2AajMAZg9UIyUlfYAVY9wzLQBBHyZs/YA1WotMQ8CbR/2AfslERSD4nD8rNd9upjpCrvsAJ6wn4AEVh9weZkCaKOf0xjy2Oz22EOJzOLAu11uGIwTGB2HUqVI70%2BmGOHhuR1w%2B3QqQSLBIpFsEA%2BqC%2B7M53NpwP2LHILLFbJOkv20qI%2B1iCwhGMB%2BwA9Hr9h4kMZgCSSIcAGxaUXi5XU637C10dROpAkjA4HWA0jYIirJgK8W/AB0ruOKNlYcO1g1YflIYRpMjLETMchsUTWJxeOzGIxEXVbBYEQgWqxeN1tqVHkLt32gnQFbzuO9AOr7LrXI1TQr0Yj%2BwArAmkwOeFoW5WfX6A/taOh0Ome6QFmH0Y8848uEt6NxB/wAlwdOR0NwPLZbECVmsSZYjnxyERtNulgBrEAWQchixJH8ADiOP8tD/QI/ySQceGHXcuGkfg2BAQctHIQ9j1PLh%2BCUEAkKfI9t3IOBYBQT08EIQVKGoOhGFYDhuAfQRhDECROBkORhGUNRNFw8h9AsQxTTQC9rHsbBHGcVwIHcCZ2hCJhMFmIZEimdJMjEnJvDaAxlOKJh5IqYYeGE0T6jGFp1MmQzalU3pml0%2BYpmBPopIMBybIiQY9MUpYlGvdZuEJXYBVvMlzkuSUMWeV5q21f5AWBUFwQrKEYVxKEkRSyd82xdd8QefziVJU4QqpLkaSEelGWZDt7W7Xl%2BUFYUqo5es1VleVGpVFrNWih5dQNI0TRMc1FzMa12odLQnUXF03Q9LBsDbfZfX9UhAw7UNwyOFN%2B1jTN1BHZMo1HHasyy1sNyyjdHkLfZi1LctfgWxqu25Rtm1Oqd21ZTthHrWJe3Wg7h32NMxwnd6FqW2d52GnamlXZLcwuh48Og/dkOfE8z0EyFvNWdYYyOCx%2BBwnQFiWd0WBwRIy0MbhYPIeDEPRri0IwrDH2fMnyHfI4jhDS0LEte9AhkCweAsCw/yg7gjgPDHWY53ClgI5A0HQHYGASciIAwDXGESckTA6LQDJwAA3Ah1jeAhsAAdwAeT5Q86IYLZSEwiBYgx2IIiaBFaP4H3WFIBF7diXRLID8hdY4YR7aYeh/a4nBYh8YAPAkehMN4fgcGLExJGTghfTqM3sGz48GVqHwtijwsRIx%2BgCFiUg/a8HAMZBAh4JzpYaCMYAlGtu3HeYKP6NEcRJBYif2I0DH9AMowTAE6xbEMZvMMgJZeVU7OAFp7cuffgSVFFzDX6wLFifh0DL0hSAIHAt5prpVLcWSnIMsI3LmfTChUtkL%2BADtK2X/m/YyjkzLSQgT0EyYDFLTHGNA5y8Df4KSkF5HyzEdx7jlizbg0I/yWn3paaQqpl7AH2B0EMWgQw8DnPgYgZACY8AWMTTm%2BEiLq1SJrCgVAdY8L4WgShPBrRIXNpbbAw8HZO3Hq7BIHsvZcSDn7KOqiQ5hwjk4KOMdmBEHjonDGKc04Z3oFnKOedTSF2PIQEuzgy4V34FXVANcNgPnrtBY8TcW5tzmp3R%2BPc%2BB9wHkPG2six451YpPJiUhZCzxUPPLiPE%2BIrwvjYISPiX471SHvbgJ8iBn3SbYa%2Bt976P2fvALyIlLLZA/p4FB39ZIIM0kUVSwCtKqRaQZWBTBrKmTyDAmp3Q%2BloLKBgnpJlgEuX6OgjymDlh404BYXBXA0YoVvoQ9QxDSHkMNlQsRtDaGMNIiwu8KyOFKzfFIP8IZpB/mkOBQI0hxwWHuYBWQ0F6YbMxuhew7MSZ4RVhAFAhAaA0G1hPRi094nyDnpxbxSBMK8XoEisFNAiAIj5B%2BQwSKGQghYLvOpfzSBIoMKSpQ6LMXYt4hS/FrciWuHQqs9Z8tuAogIOC944SEhEJIWQihppqGWiORNM2lxtn8r2ZQ6hgQjkPkBVzd80g5V/jVYET80gVUCxAsEL5%2BDULcDZthTmqyibM0NX8xVSx76ZFcNIIAA%3D).

template &lt;class T&gt;
union Vec2d {
    struct { T x; T y; };
};

template &lt;class T&gt;
constexpr Vec2d&lt;T&gt; operator+(Vec2d&lt;T&gt; const a, Vec2d&lt;T&gt; const b) {
    // Change to `Vec2d&lt;T&gt;` to fix the code
    return Vec2d{.x = a.x + b.x, .y = a.y + b.y};
}

int main() {
    Vec2d&lt;int&gt; foo{};
    Vec2d&lt;int&gt; bar{.x = 5, .y = 10};
    return (foo + bar).x;
}

Fznamznon · 2023-09-25T12:49:44Z

Reduced further:

template <class T>
struct Vec2d {
    struct { T x; };
};

void f() {
    // Change to `Vec2d<int>` to fix the code
    Vec2d v{.x = 1};
}

It is only important to have a designated init for a nested member and CTAD. Not quite clear what happens yet. The failing assertion is introduced by https://reviews.llvm.org/D139837 . https://godbolt.org/z/b4EzefEsa

github-actions bot added the new issue label Sep 22, 2023

shafik added confirmed Verified by a second party c++20 and removed new issue labels Sep 22, 2023

EugeneZelenko added clang:frontend Language frontend issues, e.g. anything involving "Sema" crash Prefer [crash-on-valid] or [crash-on-invalid] labels Sep 23, 2023

yuanfang-chen self-assigned this Sep 25, 2023

shafik mentioned this issue Dec 18, 2023

clang crashes when performing initialization on invalid code. #75781

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Parser crash when template argument is missing from designated initializer list for a union of structs #67173

Parser crash when template argument is missing from designated initializer list for a union of structs #67173

cogwheel commented Sep 22, 2023 •

edited

shafik commented Sep 22, 2023

llvmbot commented Sep 22, 2023

shafik commented Sep 22, 2023

llvmbot commented Sep 23, 2023

Fznamznon commented Sep 25, 2023

Parser crash when template argument is missing from designated initializer list for a union of structs #67173

Parser crash when template argument is missing from designated initializer list for a union of structs #67173

Comments

cogwheel commented Sep 22, 2023 • edited

shafik commented Sep 22, 2023

llvmbot commented Sep 22, 2023

shafik commented Sep 22, 2023

llvmbot commented Sep 23, 2023

Fznamznon commented Sep 25, 2023

cogwheel commented Sep 22, 2023 •

edited