Crash on invalid: ResolveSingleFunctionTemplateSpecialization

[hokein]

Bugzilla Link	49329
Version	trunk
OS	All
CC	@DougGregor,@zygoloid

Extended Description

Testcase:

template <typename T>
class C {
public:
  template<int TT>
  class Type {
  };
};

template <typename T1>
class A {
public:
  void foo() {
    C<T1>::template Type<2>;
  }
};

void test() {
    A<float> a;
    a.foo();
}

Crash stack trace:

clang: llvm-project/llvm/include/llvm/Support/Casting.h:269: typename cast_retty<X, Y *>::ret_type llvm::cast(Y *) [X = clang::FunctionTemplateDecl, Y = clang::NamedDecl]: Assertion `isa<X>(Val) && "cast<Ty>() argument of incompatible type!"' failed.
PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: ./bin/clang -cc1 -ast-dump /tmp/t1.cpp
1.      <eof> parser at end of file
2.      /tmp/t1.cpp:13:8: instantiating function definition 'A<float>::foo'
 #&#8203;0 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) llvm-project/llvm/lib/Support/Unix/Signals.inc:565:11
 #&#8203;1 PrintStackTraceSignalHandler(void*) llvm-project/llvm/lib/Support/Unix/Signals.inc:632:1
 #&#8203;2 llvm::sys::RunSignalHandlers() llvm-project/llvm/lib/Support/Signals.cpp:70:5
 #&#8203;3 SignalHandler(int) llvm-project/llvm/lib/Support/Unix/Signals.inc:407:1
 #&#8203;4 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14140)
 #&#8203;5 raise ./signal/../sysdeps/unix/sysv/linux/raise.c:51:1
 #&#8203;6 abort ./stdlib/abort.c:81:7
 #&#8203;7 get_sysdep_segment_value ./intl/loadmsgcat.c:509:8
 #&#8203;8 _nl_load_domain ./intl/loadmsgcat.c:970:34
 #&#8203;9 (/lib/x86_64-linux-gnu/libc.so.6+0x34662)
#&#8203;10 llvm::cast_retty<clang::FunctionTemplateDecl, clang::NamedDecl*>::ret_type llvm::cast<clang::FunctionTemplateDecl, clang::NamedDecl>(clang::NamedDecl*) llvm-project/llvm/include/llvm/Support/Casting.h:270:10
#&#8203;11 clang::Sema::ResolveSingleFunctionTemplateSpecialization(clang::OverloadExpr*, bool, clang::DeclAccessPair*) llvm-project/clang/lib/Sema/SemaOverload.cpp:12460:27
#&#8203;12 clang::Sema::ResolveAndFixSingleFunctionTemplateSpecialization(clang::ActionResult<clang::Expr*, true>&, bool, bool, clang::SourceRange, clang::QualType, unsigned int) llvm-project/clang/lib/Sema/SemaOverload.cpp:12525:21
#&#8203;13 clang::Sema::CheckPlaceholderExpr(clang::Expr*) llvm-project/clang/lib/Sema/SemaExpr.cpp:19272:9
#&#8203;14 clang::Sema::ActOnFinishFullExpr(clang::Expr*, clang::SourceLocation, bool, bool) llvm-project/clang/lib/Sema/SemaExprCXX.cpp:8388:16
#&#8203;15 clang::Sema::ActOnExprStmt(clang::ActionResult<clang::Expr*, true>, bool) llvm-project/clang/lib/Sema/SemaStmt.cpp:49:8
#&#8203;16 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformStmt(clang::Stmt*, clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::StmtDiscardKind) llvm-project/clang/lib/Sema/TreeTransform.h:3687:24
#&#8203;17 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCompoundStmt(clang::CompoundStmt*, bool) llvm-project/clang/lib/Sema/TreeTransform.h:7109:38
#&#8203;18 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCompoundStmt(clang::CompoundStmt*) llvm-project/clang/lib/Sema/TreeTransform.h:7095:23
#&#8203;19 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformStmt(clang::Stmt*, clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::StmtDiscardKind) llvm-project/build-debug/tools/clang/include/clang/AST/StmtNodes.inc:73:1
#&#8203;20 clang::Sema::SubstStmt(clang::Stmt*, clang::MultiLevelTemplateArgumentList const&) llvm-project/clang/lib/Sema/SemaTemplateInstantiate.cpp:3460:23
#&#8203;21 clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:4892:14
#&#8203;22 clang::Sema::PerformPendingInstantiations(bool) llvm-project/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp:6139:13
#&#8203;23 clang::Sema::ActOnEndOfTranslationUnitFragment(clang::Sema::TUFragmentKind) llvm-project/clang/lib/Sema/Sema.cpp:995:3
#&#8203;24 clang::Sema::ActOnEndOfTranslationUnit() llvm-project/clang/lib/Sema/Sema.cpp:1030:5

Looks like this is a regression, it is in trunk, but not reproducible in clang-11.0.1.

[shafik]

confirmed, godbolt: https://godbolt.org/z/YWWMqqMza

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[shafik]

Might be related to: #58301