Clang errors out after parsing out a typeid of and indexed parameter pack.

[AhmedLilah]

Version: x86-64Trunk
Platform: www.godblot.org

Source

#include <print>

auto function(auto ... inputArgs) {
    return typeid(inputArgs...[0]).name();
}


auto main() -> int {
    std::println("{}", function(5, 5.0, "char", 'c'));
    return 0;
}

Crash 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-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++26 -stdlib=libc++ -O3 <source>
1.	<source>:4:35: current parser token '.'
2.	<source>:3:35: parsing function body 'function'
3.	<source>:3:35: in compound statement ('{}')
 #0 0x0000000003742eb8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3742eb8)
 #1 0x0000000003741004 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3741004)
 #2 0x000000000368caf8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007098b0442520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00000000070ecb10 clang::Expr::HasSideEffects(clang::ASTContext const&, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x70ecb10)
 #5 0x0000000006575ffb clang::Sema::BuildCXXTypeId(clang::QualType, clang::SourceLocation, clang::Expr*, clang::SourceLocation) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x6575ffb)
 #6 0x000000000659f984 clang::Sema::ActOnCXXTypeid(clang::SourceLocation, clang::SourceLocation, bool, void*, clang::SourceLocation) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x659f984)
 #7 0x0000000005f53aff clang::Parser::ParseCXXTypeid() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f53aff)
 #8 0x0000000005f418e1 clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f418e1)
 #9 0x0000000005f4424a clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f4424a)
#10 0x0000000005f44409 clang::Parser::ParseAssignmentExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f44409)
#11 0x0000000005f49789 clang::Parser::ParseExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f49789)
#12 0x0000000005fc4d4d clang::Parser::ParseReturnStatement() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fc4d4d)
#13 0x0000000005fc902e clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fc902e)
#14 0x0000000005fca377 clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fca377)
#15 0x0000000005fcb1b1 clang::Parser::ParseCompoundStatementBody(bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fcb1b1)
#16 0x0000000005fcd71a clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fcd71a)
#17 0x0000000005ecabbb clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ecabbb)
#18 0x0000000005f1221e clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f1221e)
#19 0x0000000005ec4be7 clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ec4be7)
#20 0x0000000005ec5ad3 clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ec5ad3)
#21 0x0000000005ece15a clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ece15a)
#22 0x0000000005ecff47 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ecff47)
#23 0x0000000005ebf09a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ebf09a)
#24 0x0000000003fc577d clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fc577d)
#25 0x0000000004267c31 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x4267c31)
#26 0x00000000041eb1cb clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x41eb1cb)
#27 0x000000000434e9d3 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x434e9d3)
#28 0x0000000000c5bd9c cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc5bd9c)
#29 0x0000000000c55c8d ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#30 0x000000000400ea89 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
#31 0x000000000368cf13 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x368cf13)
#32 0x000000000400eca9 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
#33 0x0000000003fd4925 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fd4925)
#34 0x0000000003fd52fd clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fd52fd)
#35 0x0000000003fdf21c clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fdf21c)
#36 0x0000000000c59191 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc59191)
#37 0x0000000000b3a8a4 main (/opt/compiler-explorer/clang-trunk/bin/clang+++0xb3a8a4)
#38 0x00007098b0429d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#39 0x00007098b0429e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#40 0x0000000000c5572e _start (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc5572e)
clang++: error: clang frontend command failed with exit code 139 (use -v to see invocation)
Compiler returned: 139

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Ahmed S. Lilah (AhmedLilah)

Version: x86-64Trunk Platform: www.godblot.org

Source

#include <print>

auto function(auto ... inputArgs) {
    return typeid(inputArgs...[0]).name();
}


auto main() -> int {
    std::println("{}", function(5, 5.0, "char", 'c'));
    return 0;
}

Crash 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-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++26 -stdlib=libc++ -O3 <source>
1.	<source>:4:35: current parser token '.'
2.	<source>:3:35: parsing function body 'function'
3.	<source>:3:35: in compound statement ('{}')
 #<!-- -->0 0x0000000003742eb8 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3742eb8)
 #<!-- -->1 0x0000000003741004 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3741004)
 #<!-- -->2 0x000000000368caf8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #<!-- -->3 0x00007098b0442520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #<!-- -->4 0x00000000070ecb10 clang::Expr::HasSideEffects(clang::ASTContext const&amp;, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x70ecb10)
 #<!-- -->5 0x0000000006575ffb clang::Sema::BuildCXXTypeId(clang::QualType, clang::SourceLocation, clang::Expr*, clang::SourceLocation) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x6575ffb)
 #<!-- -->6 0x000000000659f984 clang::Sema::ActOnCXXTypeid(clang::SourceLocation, clang::SourceLocation, bool, void*, clang::SourceLocation) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x659f984)
 #<!-- -->7 0x0000000005f53aff clang::Parser::ParseCXXTypeid() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f53aff)
 #<!-- -->8 0x0000000005f418e1 clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&amp;, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f418e1)
 #<!-- -->9 0x0000000005f4424a clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f4424a)
#<!-- -->10 0x0000000005f44409 clang::Parser::ParseAssignmentExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f44409)
#<!-- -->11 0x0000000005f49789 clang::Parser::ParseExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f49789)
#<!-- -->12 0x0000000005fc4d4d clang::Parser::ParseReturnStatement() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fc4d4d)
#<!-- -->13 0x0000000005fc902e clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector&lt;clang::Stmt*, 32u&gt;&amp;, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fc902e)
#<!-- -->14 0x0000000005fca377 clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector&lt;clang::Stmt*, 32u&gt;&amp;, clang::Parser::ParsedStmtContext, clang::SourceLocation*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fca377)
#<!-- -->15 0x0000000005fcb1b1 clang::Parser::ParseCompoundStatementBody(bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fcb1b1)
#<!-- -->16 0x0000000005fcd71a clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&amp;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fcd71a)
#<!-- -->17 0x0000000005ecabbb clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&amp;, clang::Parser::ParsedTemplateInfo const&amp;, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ecabbb)
#<!-- -->18 0x0000000005f1221e clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&amp;, clang::DeclaratorContext, clang::ParsedAttributes&amp;, clang::Parser::ParsedTemplateInfo&amp;, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f1221e)
#<!-- -->19 0x0000000005ec4be7 clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::ParsingDeclSpec&amp;, clang::AccessSpecifier) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ec4be7)
#<!-- -->20 0x0000000005ec5ad3 clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::ParsingDeclSpec*, clang::AccessSpecifier) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ec5ad3)
#<!-- -->21 0x0000000005ece15a clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ece15a)
#<!-- -->22 0x0000000005ecff47 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&lt;clang::DeclGroupRef&gt;&amp;, clang::Sema::ModuleImportState&amp;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ecff47)
#<!-- -->23 0x0000000005ebf09a clang::ParseAST(clang::Sema&amp;, bool, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ebf09a)
#<!-- -->24 0x0000000003fc577d clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fc577d)
#<!-- -->25 0x0000000004267c31 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x4267c31)
#<!-- -->26 0x00000000041eb1cb clang::CompilerInstance::ExecuteAction(clang::FrontendAction&amp;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x41eb1cb)
#<!-- -->27 0x000000000434e9d3 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x434e9d3)
#<!-- -->28 0x0000000000c5bd9c cc1_main(llvm::ArrayRef&lt;char const*&gt;, char const*, void*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc5bd9c)
#<!-- -->29 0x0000000000c55c8d ExecuteCC1Tool(llvm::SmallVectorImpl&lt;char const*&gt;&amp;, llvm::ToolContext const&amp;) driver.cpp:0:0
#<!-- -->30 0x000000000400ea89 void llvm::function_ref&lt;void ()&gt;::callback_fn&lt;clang::driver::CC1Command::Execute(llvm::ArrayRef&lt;std::optional&lt;llvm::StringRef&gt;&gt;, std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt;&gt;*, bool*) const::'lambda'()&gt;(long) Job.cpp:0:0
#<!-- -->31 0x000000000368cf13 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref&lt;void ()&gt;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x368cf13)
#<!-- -->32 0x000000000400eca9 clang::driver::CC1Command::Execute(llvm::ArrayRef&lt;std::optional&lt;llvm::StringRef&gt;&gt;, std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt;&gt;*, bool*) const (.part.0) Job.cpp:0:0
#<!-- -->33 0x0000000003fd4925 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&amp;, clang::driver::Command const*&amp;, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fd4925)
#<!-- -->34 0x0000000003fd52fd clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&amp;, llvm::SmallVectorImpl&lt;std::pair&lt;int, clang::driver::Command const*&gt;&gt;&amp;, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fd52fd)
#<!-- -->35 0x0000000003fdf21c clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&amp;, llvm::SmallVectorImpl&lt;std::pair&lt;int, clang::driver::Command const*&gt;&gt;&amp;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fdf21c)
#<!-- -->36 0x0000000000c59191 clang_main(int, char**, llvm::ToolContext const&amp;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc59191)
#<!-- -->37 0x0000000000b3a8a4 main (/opt/compiler-explorer/clang-trunk/bin/clang+++0xb3a8a4)
#<!-- -->38 0x00007098b0429d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#<!-- -->39 0x00007098b0429e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#<!-- -->40 0x0000000000c5572e _start (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc5572e)
clang++: error: clang frontend command failed with exit code 139 (use -v to see invocation)
Compiler returned: 139

[cor3ntin]

In HasSideEffects we should always return false for PackIndexingExpr (because the selected expression it always an id expression), that way we don't have to try to recurse in a selected expression we might not have.

[llvmbot]

Hi!

This issue may be a good introductory issue for people new to working on LLVM. If you would like to work on this issue, your first steps are:

1. Check that no other contributor has already been assigned to this issue. If you believe that no one is actually working on it despite an assignment, ping the person. After one week without a response, the assignee may be changed.
2. In the comments of this issue, request for it to be assigned to you, or just create a pull request after following the steps below. Mention this issue in the description of the pull request.
3. Fix the issue locally.
4. Run the test suite locally. Remember that the subdirectories under test/ create fine-grained testing targets, so you can e.g. use make check-clang-ast to only run Clang's AST tests.
5. Create a Git commit.
6. Run git clang-format HEAD~1 to format your changes.
7. Open a pull request to the upstream repository on GitHub. Detailed instructions can be found in GitHub's documentation. Mention this issue in the description of the pull request.

If you have any further questions about this issue, don't hesitate to ask via a comment in the thread below.

[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Ahmed S. Lilah (AhmedLilah)

Version: x86-64Trunk Platform: www.godblot.org

Source

#include <print>

auto function(auto ... inputArgs) {
    return typeid(inputArgs...[0]).name();
}


auto main() -> int {
    std::println("{}", function(5, 5.0, "char", 'c'));
    return 0;
}

Crash 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-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++26 -stdlib=libc++ -O3 <source>
1.	<source>:4:35: current parser token '.'
2.	<source>:3:35: parsing function body 'function'
3.	<source>:3:35: in compound statement ('{}')
 #<!-- -->0 0x0000000003742eb8 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3742eb8)
 #<!-- -->1 0x0000000003741004 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3741004)
 #<!-- -->2 0x000000000368caf8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #<!-- -->3 0x00007098b0442520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #<!-- -->4 0x00000000070ecb10 clang::Expr::HasSideEffects(clang::ASTContext const&amp;, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x70ecb10)
 #<!-- -->5 0x0000000006575ffb clang::Sema::BuildCXXTypeId(clang::QualType, clang::SourceLocation, clang::Expr*, clang::SourceLocation) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x6575ffb)
 #<!-- -->6 0x000000000659f984 clang::Sema::ActOnCXXTypeid(clang::SourceLocation, clang::SourceLocation, bool, void*, clang::SourceLocation) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x659f984)
 #<!-- -->7 0x0000000005f53aff clang::Parser::ParseCXXTypeid() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f53aff)
 #<!-- -->8 0x0000000005f418e1 clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&amp;, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f418e1)
 #<!-- -->9 0x0000000005f4424a clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f4424a)
#<!-- -->10 0x0000000005f44409 clang::Parser::ParseAssignmentExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f44409)
#<!-- -->11 0x0000000005f49789 clang::Parser::ParseExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f49789)
#<!-- -->12 0x0000000005fc4d4d clang::Parser::ParseReturnStatement() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fc4d4d)
#<!-- -->13 0x0000000005fc902e clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector&lt;clang::Stmt*, 32u&gt;&amp;, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fc902e)
#<!-- -->14 0x0000000005fca377 clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector&lt;clang::Stmt*, 32u&gt;&amp;, clang::Parser::ParsedStmtContext, clang::SourceLocation*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fca377)
#<!-- -->15 0x0000000005fcb1b1 clang::Parser::ParseCompoundStatementBody(bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fcb1b1)
#<!-- -->16 0x0000000005fcd71a clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&amp;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5fcd71a)
#<!-- -->17 0x0000000005ecabbb clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&amp;, clang::Parser::ParsedTemplateInfo const&amp;, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ecabbb)
#<!-- -->18 0x0000000005f1221e clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&amp;, clang::DeclaratorContext, clang::ParsedAttributes&amp;, clang::Parser::ParsedTemplateInfo&amp;, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f1221e)
#<!-- -->19 0x0000000005ec4be7 clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::ParsingDeclSpec&amp;, clang::AccessSpecifier) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ec4be7)
#<!-- -->20 0x0000000005ec5ad3 clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::ParsingDeclSpec*, clang::AccessSpecifier) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ec5ad3)
#<!-- -->21 0x0000000005ece15a clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ece15a)
#<!-- -->22 0x0000000005ecff47 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&lt;clang::DeclGroupRef&gt;&amp;, clang::Sema::ModuleImportState&amp;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ecff47)
#<!-- -->23 0x0000000005ebf09a clang::ParseAST(clang::Sema&amp;, bool, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ebf09a)
#<!-- -->24 0x0000000003fc577d clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fc577d)
#<!-- -->25 0x0000000004267c31 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x4267c31)
#<!-- -->26 0x00000000041eb1cb clang::CompilerInstance::ExecuteAction(clang::FrontendAction&amp;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x41eb1cb)
#<!-- -->27 0x000000000434e9d3 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x434e9d3)
#<!-- -->28 0x0000000000c5bd9c cc1_main(llvm::ArrayRef&lt;char const*&gt;, char const*, void*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc5bd9c)
#<!-- -->29 0x0000000000c55c8d ExecuteCC1Tool(llvm::SmallVectorImpl&lt;char const*&gt;&amp;, llvm::ToolContext const&amp;) driver.cpp:0:0
#<!-- -->30 0x000000000400ea89 void llvm::function_ref&lt;void ()&gt;::callback_fn&lt;clang::driver::CC1Command::Execute(llvm::ArrayRef&lt;std::optional&lt;llvm::StringRef&gt;&gt;, std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt;&gt;*, bool*) const::'lambda'()&gt;(long) Job.cpp:0:0
#<!-- -->31 0x000000000368cf13 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref&lt;void ()&gt;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x368cf13)
#<!-- -->32 0x000000000400eca9 clang::driver::CC1Command::Execute(llvm::ArrayRef&lt;std::optional&lt;llvm::StringRef&gt;&gt;, std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt;&gt;*, bool*) const (.part.0) Job.cpp:0:0
#<!-- -->33 0x0000000003fd4925 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&amp;, clang::driver::Command const*&amp;, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fd4925)
#<!-- -->34 0x0000000003fd52fd clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&amp;, llvm::SmallVectorImpl&lt;std::pair&lt;int, clang::driver::Command const*&gt;&gt;&amp;, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fd52fd)
#<!-- -->35 0x0000000003fdf21c clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&amp;, llvm::SmallVectorImpl&lt;std::pair&lt;int, clang::driver::Command const*&gt;&gt;&amp;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fdf21c)
#<!-- -->36 0x0000000000c59191 clang_main(int, char**, llvm::ToolContext const&amp;) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc59191)
#<!-- -->37 0x0000000000b3a8a4 main (/opt/compiler-explorer/clang-trunk/bin/clang+++0xb3a8a4)
#<!-- -->38 0x00007098b0429d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#<!-- -->39 0x00007098b0429e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#<!-- -->40 0x0000000000c5572e _start (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc5572e)
clang++: error: clang frontend command failed with exit code 139 (use -v to see invocation)
Compiler returned: 139

[AhmedLilah]

Hi there,

I want to start contributing to the project.

Can you give me a heads up on how to start and how to get started fixing this bug?

And how do I get it assigned to me?

[Endilll]

You should check out our documentation: https://clang.llvm.org/get_started.html
Then you should reproduce the crash locally.
After that you can navigate to

llvm-project/clang/lib/AST/Expr.cpp

Lines 3624 to 3626 in 4bce270

	case PackIndexingExprClass:
	return cast<PackIndexingExpr>(this)->getSelectedExpr()->HasSideEffects(
	Ctx, IncludePossibleEffects);

, apply Corentin's suggestion and see if it helps.