[Clang] Crash when taking the address of a capture in a lambda with an explicit object parameter in overload pattern

[Sirraide]

Just documenting this here in case anyone else runs into this; from what I can tell, #84473 already fixes this. I haven’t really looked into this case in particular, but presumably, it’s broken because we currently erroneously treat by-reference captures as dependent in deducing-this lambdas even though they shouldn’t be. It was broken because of that, but the underlying problem is a different one. See below.

This asserts in codegen (https://godbolt.org/z/1czjnznMK):

template <typename... Ts>
struct Overloaded : Ts... {
    using Ts::operator()...;
};

template <typename... Ts>
Overloaded(Ts...) -> Overloaded<Ts...>;

void f() {
    int x;
    Overloaded o {
        [&](this auto& self) {
            (void) &x;
        }
    };
    o();
}

Assertion:

clang++: /root/llvm-project/clang/lib/CodeGen/CGValue.h:277: 
void clang::CodeGen::LValue::initializeSimpleLValue(clang::CodeGen::Address, clang::QualType, clang::CodeGen::LValueBaseInfo, clang::CodeGen::TBAAAccessInfo, clang::ASTContext&): 
Assertion `Addr.getBasePointer()->getType()->isPointerTy()' failed.

Stack trace:

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++2c <source>
1.	<eof> parser at end of file
2.	Per-file LLVM IR generation
3.	<source>:12:9: Generating code for declaration 'f()::(anonymous class)::operator()'
 #0 0x0000000003928918 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3928918)
 #1 0x00000000039265fc llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x39265fc)
 #2 0x000000000386cba8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f2d0a042520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007f2d0a0969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x00007f2d0a042476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x00007f2d0a0287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x00007f2d0a02871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x00007f2d0a039e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x0000000003c3e46c clang::CodeGen::LValue::MakeAddr(clang::CodeGen::Address, clang::QualType, clang::ASTContext&, clang::CodeGen::LValueBaseInfo, clang::CodeGen::TBAAAccessInfo) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3c3e46c)
#10 0x000000000404970f clang::CodeGen::CodeGenFunction::EmitLValueForField(clang::CodeGen::LValue, clang::FieldDecl const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x404970f)
#11 0x000000000404afdd clang::CodeGen::CodeGenFunction::EmitLValueForLambdaField(clang::FieldDecl const*, llvm::Value*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x404afdd)
#12 0x0000000004057af5 clang::CodeGen::CodeGenFunction::EmitDeclRefLValue(clang::DeclRefExpr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4057af5)
#13 0x00000000040549d2 clang::CodeGen::CodeGenFunction::EmitLValueHelper(clang::Expr const*, clang::CodeGen::KnownNonNull_t) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x40549d2)
#14 0x0000000004054d11 clang::CodeGen::CodeGenFunction::EmitLValue(clang::Expr const*, clang::CodeGen::KnownNonNull_t) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4054d11)
#15 0x00000000040a94ff clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#16 0x00000000040ae26c clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x40ae26c)
#17 0x000000000403f14e clang::CodeGen::CodeGenFunction::EmitAnyExpr(clang::Expr const*, clang::CodeGen::AggValueSlot, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x403f14e)
#18 0x0000000004060dc1 clang::CodeGen::CodeGenFunction::EmitIgnoredExpr(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4060dc1)
#19 0x00000000040b0437 (anonymous namespace)::ScalarExprEmitter::VisitCastExpr(clang::CastExpr*) CGExprScalar.cpp:0:0
#20 0x00000000040a7a53 clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#21 0x00000000040ae26c clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x40ae26c)
#22 0x000000000403f14e clang::CodeGen::CodeGenFunction::EmitAnyExpr(clang::Expr const*, clang::CodeGen::AggValueSlot, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x403f14e)
#23 0x0000000004060dc1 clang::CodeGen::CodeGenFunction::EmitIgnoredExpr(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4060dc1)
#24 0x0000000003c4f155 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3c4f155)
#25 0x0000000003c559ec clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3c559ec)
#26 0x0000000003cb79b1 clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3cb79b1)
#27 0x0000000003ccb2ca clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3ccb2ca)
#28 0x0000000003d2a8d2 clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3d2a8d2)
#29 0x0000000003d25195 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3d25195)
#30 0x0000000003d3123d clang::CodeGen::CodeGenModule::EmitDeferred() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3d3123d)
#31 0x0000000003d33ae3 clang::CodeGen::CodeGenModule::Release() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3d33ae3)
#32 0x00000000041d538e (anonymous namespace)::CodeGeneratorImpl::HandleTranslationUnit(clang::ASTContext&) ModuleBuilder.cpp:0:0
#33 0x00000000041d3ea5 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41d3ea5)
#34 0x00000000061d59bc clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x61d59bc)
#35 0x00000000041d3768 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41d3768)
#36 0x0000000004453779 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4453779)
#37 0x00000000043dd09e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43dd09e)
#38 0x00000000045364ee clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x45364ee)
#39 0x0000000000c3e6ec cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc3e6ec)
#40 0x0000000000c3797a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#41 0x00000000042166e9 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
#42 0x000000000386d054 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x386d054)
#43 0x0000000004216cdf 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
#44 0x00000000041dd075 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41dd075)
#45 0x00000000041ddadd 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+++0x41ddadd)
#46 0x00000000041e5845 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41e5845)
#47 0x0000000000c3bb85 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc3bb85)
#48 0x0000000000b1ed54 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xb1ed54)
#49 0x00007f2d0a029d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#50 0x00007f2d0a029e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#51 0x0000000000c3746e _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc3746e)

[llvmbot]

@llvm/issue-subscribers-clang-codegen

Author: None (Sirraide)

Just documenting this here in case anyone else runs into this; from what I can tell, #84473 already fixes this. I haven’t really looked into this case in particular, but presumably, it’s broken because we currently erroneously treat by-reference captures as dependent in deducing-`this` lambdas even though they shouldn’t be.

This asserts in codegen (https://godbolt.org/z/1czjnznMK):

template <typename... Ts>
struct Overloaded : Ts... {
    using Ts::operator()...;
};

template <typename... Ts>
Overloaded(Ts...) -> Overloaded<Ts...>;

void f() {
    int x;
    Overloaded o {
        [&](this auto& self) {
            (void) &x;
        }
    };
    o();
}

Assertion:

clang++: /root/llvm-project/clang/lib/CodeGen/CGValue.h:277: 
void clang::CodeGen::LValue::initializeSimpleLValue(clang::CodeGen::Address, clang::QualType, clang::CodeGen::LValueBaseInfo, clang::CodeGen::TBAAAccessInfo, clang::ASTContext&): 
Assertion `Addr.getBasePointer()->getType()->isPointerTy()' failed.

Stack trace:

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++2c <source>
1.	<eof> parser at end of file
2.	Per-file LLVM IR generation
3.	<source>:12:9: Generating code for declaration 'f()::(anonymous class)::operator()'
 #<!-- -->0 0x0000000003928918 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3928918)
 #<!-- -->1 0x00000000039265fc llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x39265fc)
 #<!-- -->2 0x000000000386cba8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #<!-- -->3 0x00007f2d0a042520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #<!-- -->4 0x00007f2d0a0969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #<!-- -->5 0x00007f2d0a042476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #<!-- -->6 0x00007f2d0a0287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #<!-- -->7 0x00007f2d0a02871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #<!-- -->8 0x00007f2d0a039e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #<!-- -->9 0x0000000003c3e46c clang::CodeGen::LValue::MakeAddr(clang::CodeGen::Address, clang::QualType, clang::ASTContext&amp;, clang::CodeGen::LValueBaseInfo, clang::CodeGen::TBAAAccessInfo) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3c3e46c)
#<!-- -->10 0x000000000404970f clang::CodeGen::CodeGenFunction::EmitLValueForField(clang::CodeGen::LValue, clang::FieldDecl const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x404970f)
#<!-- -->11 0x000000000404afdd clang::CodeGen::CodeGenFunction::EmitLValueForLambdaField(clang::FieldDecl const*, llvm::Value*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x404afdd)
#<!-- -->12 0x0000000004057af5 clang::CodeGen::CodeGenFunction::EmitDeclRefLValue(clang::DeclRefExpr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4057af5)
#<!-- -->13 0x00000000040549d2 clang::CodeGen::CodeGenFunction::EmitLValueHelper(clang::Expr const*, clang::CodeGen::KnownNonNull_t) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x40549d2)
#<!-- -->14 0x0000000004054d11 clang::CodeGen::CodeGenFunction::EmitLValue(clang::Expr const*, clang::CodeGen::KnownNonNull_t) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4054d11)
#<!-- -->15 0x00000000040a94ff clang::StmtVisitorBase&lt;std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*&gt;::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#<!-- -->16 0x00000000040ae26c clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x40ae26c)
#<!-- -->17 0x000000000403f14e clang::CodeGen::CodeGenFunction::EmitAnyExpr(clang::Expr const*, clang::CodeGen::AggValueSlot, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x403f14e)
#<!-- -->18 0x0000000004060dc1 clang::CodeGen::CodeGenFunction::EmitIgnoredExpr(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4060dc1)
#<!-- -->19 0x00000000040b0437 (anonymous namespace)::ScalarExprEmitter::VisitCastExpr(clang::CastExpr*) CGExprScalar.cpp:0:0
#<!-- -->20 0x00000000040a7a53 clang::StmtVisitorBase&lt;std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*&gt;::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#<!-- -->21 0x00000000040ae26c clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x40ae26c)
#<!-- -->22 0x000000000403f14e clang::CodeGen::CodeGenFunction::EmitAnyExpr(clang::Expr const*, clang::CodeGen::AggValueSlot, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x403f14e)
#<!-- -->23 0x0000000004060dc1 clang::CodeGen::CodeGenFunction::EmitIgnoredExpr(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4060dc1)
#<!-- -->24 0x0000000003c4f155 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef&lt;clang::Attr const*&gt;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3c4f155)
#<!-- -->25 0x0000000003c559ec clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&amp;, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3c559ec)
#<!-- -->26 0x0000000003cb79b1 clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3cb79b1)
#<!-- -->27 0x0000000003ccb2ca clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3ccb2ca)
#<!-- -->28 0x0000000003d2a8d2 clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3d2a8d2)
#<!-- -->29 0x0000000003d25195 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3d25195)
#<!-- -->30 0x0000000003d3123d clang::CodeGen::CodeGenModule::EmitDeferred() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3d3123d)
#<!-- -->31 0x0000000003d33ae3 clang::CodeGen::CodeGenModule::Release() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3d33ae3)
#<!-- -->32 0x00000000041d538e (anonymous namespace)::CodeGeneratorImpl::HandleTranslationUnit(clang::ASTContext&amp;) ModuleBuilder.cpp:0:0
#<!-- -->33 0x00000000041d3ea5 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41d3ea5)
#<!-- -->34 0x00000000061d59bc clang::ParseAST(clang::Sema&amp;, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x61d59bc)
#<!-- -->35 0x00000000041d3768 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41d3768)
#<!-- -->36 0x0000000004453779 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4453779)
#<!-- -->37 0x00000000043dd09e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43dd09e)
#<!-- -->38 0x00000000045364ee clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x45364ee)
#<!-- -->39 0x0000000000c3e6ec cc1_main(llvm::ArrayRef&lt;char const*&gt;, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc3e6ec)
#<!-- -->40 0x0000000000c3797a ExecuteCC1Tool(llvm::SmallVectorImpl&lt;char const*&gt;&amp;, llvm::ToolContext const&amp;) driver.cpp:0:0
#<!-- -->41 0x00000000042166e9 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
#<!-- -->42 0x000000000386d054 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref&lt;void ()&gt;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x386d054)
#<!-- -->43 0x0000000004216cdf 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
#<!-- -->44 0x00000000041dd075 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&amp;, clang::driver::Command const*&amp;, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41dd075)
#<!-- -->45 0x00000000041ddadd 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-assertions-trunk/bin/clang+++0x41ddadd)
#<!-- -->46 0x00000000041e5845 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-assertions-trunk/bin/clang+++0x41e5845)
#<!-- -->47 0x0000000000c3bb85 clang_main(int, char**, llvm::ToolContext const&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc3bb85)
#<!-- -->48 0x0000000000b1ed54 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xb1ed54)
#<!-- -->49 0x00007f2d0a029d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#<!-- -->50 0x00007f2d0a029e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#<!-- -->51 0x0000000000c3746e _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc3746e)

[Sirraide]

Actually, it turns out this is only ‘fixed’ for this case because we now (after #84473) no longer treat by-reference captures as dependent; so this is actually a separate problem and after #84473 is broken for by-copy captures instead. I’ll look into this a bit more.

[Sirraide]

I may end up making the fix for this part of #84473 seeing as there are two problems here (1. we’re erroneously making by-reference captures dependent; this is fixed by #84473, and 2. we’re for some reason crashing on dependent captures here).

Making this a separate pr would mean I’d have to write a test case that purposefully uses by-reference captures so we get a dependent capture—even though those shouldn’t be dependent to begin with, and it seems a bit weird to me to introduce a test that purposefully relies on incorrect behaviour.

[Sirraide]

The issue here appears to be that when attempting to load the field at index 0, we use the Overloaded type as the base of the load and not the type of the lambda, so the result type of the load ends up being the lambda itself (which is the ‘first field’ because it’s the base class of the Overloaded type) instead of its first capture.

[Sirraide]

For non-lambda class types, this problem is solved by inserting an UncheckedDerivedToBase cast in the member access; I think we need to do the equivalent of that in codegen, because we don’t have a member access here to begin with.