[Clang] Assertion `isa<LabelDecl>(D) && "declaration not instantiated in this scope"` failed since 10.0

***Generated by fuzzer.***
Clang trunk crashed and goes back to 10.0 with `-std=c++20` flag.
Compiler Explorer: https://godbolt.org/z/6rK99sKef

## Program
```cpp
template int bar(T) {
int d = 0;
if constexpr (requires { requires(sizeof(int) > d); })
}
```

## Stack Dump
```bash
clang++: /root/llvm-project/llvm/tools/clang/lib/Sema/SemaTemplateInstantiate.cpp:4632: llvm::PointerUnion*>* clang::LocalInstantiationScope::findInstantiationOf(const clang::Decl*): Assertion `isa(D) && "declaration not instantiated in this scope"' failed.
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++ -g -o /app/output.s -mllvm --x86-asm-syntax=intel -fno-verbose-asm -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++20
1. :3:53: current parser token ';'
2. :1:31: parsing function body 'bar'
3. :1:31: in compound statement ('{}')
#0 0x0000000004309158 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4309158)
#1 0x0000000004306584 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4306584)
#2 0x00000000042492d8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
#3 0x00007e0f4c642520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
#4 0x00007e0f4c6969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
#5 0x00007e0f4c642476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
#6 0x00007e0f4c6287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
#7 0x00007e0f4c62871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
#8 0x00007e0f4c639e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#9 0x00000000075898ed clang::LocalInstantiationScope::findInstantiationOf(clang::Decl const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x75898ed)
#10 0x0000000007670f77 clang::Sema::FindInstantiatedDecl(clang::SourceLocation, clang::NamedDecl*, clang::MultiLevelTemplateArgumentList const&, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7670f77)
#11 0x00000000075b0953 (anonymous namespace)::TemplateInstantiator::TransformDecl(clang::SourceLocation, clang::Decl*) SemaTemplateInstantiate.cpp:0:0
#12 0x00000000075c60f0 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformDeclRefExpr(clang::DeclRefExpr*) SemaTemplateInstantiate.cpp:0:0
#13 0x00000000075c65fb (anonymous namespace)::TemplateInstantiator::TransformDeclRefExpr(clang::DeclRefExpr*) SemaTemplateInstantiate.cpp:0:0
#14 0x00000000075961e3 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#15 0x00000000075b5e75 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformInitializer(clang::Expr*, bool) (.part.0) SemaTemplateInstantiate.cpp:0:0
#16 0x00000000075b66c0 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformBinaryOperator(clang::BinaryOperator*) SemaTemplateInstantiate.cpp:0:0
#17 0x0000000007595e6c clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#18 0x00000000075d0397 clang::Sema::SubstConstraintExpr(clang::Expr*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x75d0397)
#19 0x0000000006d98604 (anonymous namespace)::ConstraintSatisfactionChecker::Evaluate(clang::AtomicConstraint const&, clang::MultiLevelTemplateArgumentList const&) SemaConcept.cpp:0:0
#20 0x0000000006d9cee7 CheckConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, llvm::ArrayRef, clang::MultiLevelTemplateArgumentList const&, clang::SourceRange, clang::ConstraintSatisfaction&, clang::Expr**, clang::ConceptReference const*) SemaConcept.cpp:0:0
#21 0x0000000006d9d4df clang::Sema::CheckConstraintSatisfaction(llvm::PointerUnion, llvm::ArrayRef, clang::MultiLevelTemplateArgumentList const&, clang::SourceRange, clang::ConstraintSatisfaction&, clang::ConceptReference const*, clang::Expr**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6d9d4df)
#22 0x00000000070765c5 clang::Sema::BuildNestedRequirement(clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x70765c5)
#23 0x0000000006adf600 clang::Parser::ParseRequiresExpression() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6adf600)
#24 0x0000000006acdaf1 clang::Parser::ParseCastExpression(clang::CastParseKind, bool, bool&, clang::TypoCorrectionTypeBehavior, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6acdaf1)
#25 0x0000000006acf1a7 clang::Parser::ParseCastExpression(clang::CastParseKind, bool, clang::TypoCorrectionTypeBehavior, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6acf1a7)
#26 0x0000000006acf239 clang::Parser::ParseAssignmentExpression(clang::TypoCorrectionTypeBehavior) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6acf239)
#27 0x0000000006ad3819 clang::Parser::ParseExpression(clang::TypoCorrectionTypeBehavior) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ad3819)
#28 0x0000000006ae4c42 clang::Parser::ParseCXXCondition(clang::ActionResult*, clang::SourceLocation, clang::Sema::ConditionKind, bool, clang::Parser::ForRangeInfo*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ae4c42)
#29 0x0000000006b4d73b clang::Parser::ParseParenExprOrCondition(clang::ActionResult*, clang::Sema::ConditionResult&, clang::SourceLocation, clang::Sema::ConditionKind, clang::SourceLocation&, clang::SourceLocation&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6b4d73b)
#30 0x0000000006b5223d clang::Parser::ParseIfStatement(clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6b5223d)
#31 0x0000000006b5007d clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::LabelDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6b5007d)
#32 0x0000000006b50f76 clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::LabelDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6b50f76)
#33 0x0000000006b598be clang::Parser::ParseCompoundStatementBody(bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6b598be)
#34 0x0000000006b5a10a clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6b5a10a)
#35 0x0000000006a6055b clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a6055b)
#36 0x0000000006a969cd clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a969cd)
#37 0x0000000006b66058 clang::Parser::ParseDeclarationAfterTemplate(clang::DeclaratorContext, clang::Parser::ParsedTemplateInfo&, clang::ParsingDeclRAIIObject&, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6b66058)
#38 0x0000000006b73549 clang::Parser::ParseTemplateDeclarationOrSpecialization(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (.part.0) ParseTemplate.cpp:0:0
#39 0x0000000006b7395a clang::Parser::ParseDeclarationStartingWithTemplate(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6b7395a)
#40 0x0000000006a9f340 clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a9f340)
#41 0x0000000006a5bd8c clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a5bd8c)
#42 0x0000000006a5cc75 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a5cc75)
#43 0x0000000006a5d120 clang::Parser::ParseFirstTopLevelDecl(clang::OpaquePtr&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a5d120)
#44 0x0000000006a3dcc3 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a3dcc3)
#45 0x0000000004c6c068 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c6c068)
#46 0x0000000004f65455 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f65455)
#47 0x0000000004ee528e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ee528e)
#48 0x000000000505fafd clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x505fafd)
#49 0x0000000000de89de cc1_main(llvm::ArrayRef, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xde89de)
#50 0x0000000000ddf3aa ExecuteCC1Tool(llvm::SmallVectorImpl&, llvm::ToolContext const&, llvm::IntrusiveRefCntPtr) driver.cpp:0:0
#51 0x0000000000ddf52d int llvm::function_ref&)>::callback_fn&)>(long, llvm::SmallVectorImpl&) driver.cpp:0:0
#52 0x0000000004cdf0a9 void llvm::function_ref::callback_fn>, std::__cxx11::basic_string, std::allocator>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#53 0x0000000004249774 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4249774)
#54 0x0000000004cdf6bf clang::driver::CC1Command::Execute(llvm::ArrayRef>, std::__cxx11::basic_string, std::allocator>*, bool*) const (.part.0) Job.cpp:0:0
#55 0x0000000004ca0052 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ca0052)
#56 0x0000000004ca0ffe clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ca0ffe)
#57 0x0000000004ca8455 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ca8455)
#58 0x0000000000de4d51 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xde4d51)
#59 0x0000000000c8f044 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc8f044)
#60 0x00007e0f4c629d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#61 0x00007e0f4c629e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#62 0x0000000000ddee45 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xddee45)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134
```

Reproduce the crash with the provided C++20 program and compiler flags, using the Compiler Explorer link if needed. Start in llvm/tools/clang/lib/Sema/SemaTemplateInstantiate.cpp, especially LocalInstantiationScope::findInstantiationOf and the instantiation path shown in the stack. Done means the reproducer no longer triggers the assertion and coverage is added for this case.

Written by the indexing model from the issue text.