[clang] Assertion `Conv == Best->FoundDecl.getDecl() && "Found Decl & conversion-to-functionptr should be same, right?!"' failed.

Reproducer:
https://godbolt.org/z/G6Pq6q7TM
```cpp
struct M {
template static int static_foo(T) {
return 5;
}
template operator T() { return T{}; }
operator auto() { return &static_foo; }
};

struct N : M {
using M::operator auto;
};

template int test() {
int j = T{}(3);
return 0;
}

int Ninst = test();
```

Backtrace:
```console
clang++: /root/llvm-project/llvm/tools/clang/lib/Sema/SemaOverload.cpp:16709: clang::ExprResult clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, clang::MultiExprArg, clang::SourceLocation): Assertion `Conv == Best->FoundDecl.getDecl() && "Found Decl & conversion-to-functionptr should be same, right?!"' 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
1. parser at end of file
2. :13:24: instantiating function definition 'test'
#0 0x00000000044e6fc8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x44e6fc8)
#1 0x00000000044e3df4 llvm::sys::RunSignalHandlers() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x44e3df4)
#2 0x00000000044e4414 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x44e4414)
#3 0x00000000044236b8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
#4 0x0000744650c42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
#5 0x0000744650c969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
#6 0x0000744650c42476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
#7 0x0000744650c287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
#8 0x0000744650c2871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
#9 0x0000744650c39e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#10 0x00000000076e1eff clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef, clang::SourceLocation) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x76e1eff)
#11 0x00000000073298c2 clang::Sema::BuildCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef, clang::SourceLocation, clang::Expr*, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x73298c2)
#12 0x000000000732e7ff clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef, clang::SourceLocation, clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x732e7ff)
#13 0x0000000007922963 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCallExpr(clang::CallExpr*) SemaTemplateInstantiate.cpp:0:0
#14 0x00000000078ff1c7 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#15 0x000000000791f418 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformInitializer(clang::Expr*, bool) (.part.0) SemaTemplateInstantiate.cpp:0:0
#16 0x000000000792004b clang::Sema::SubstInitializer(clang::Expr*, clang::MultiLevelTemplateArgumentList const&, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x792004b)
#17 0x000000000798d8f8 clang::Sema::InstantiateVariableInitializer(clang::VarDecl*, clang::VarDecl*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x798d8f8)
#18 0x00000000079e0ddc clang::Sema::BuildVariableInstantiation(clang::VarDecl*, clang::VarDecl*, clang::MultiLevelTemplateArgumentList const&, llvm::SmallVector*, clang::DeclContext*, clang::LocalInstantiationScope*, bool, clang::VarTemplateSpecializationDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x79e0ddc)
#19 0x00000000079edf93 clang::TemplateDeclInstantiator::VisitVarDecl(clang::VarDecl*, bool, llvm::ArrayRef*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x79edf93)
#20 0x00000000079f4314 void llvm::function_ref::callback_fn(long) SemaTemplateInstantiateDecl.cpp:0:0
#21 0x000000000883f2a1 clang::StackExhaustionHandler::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x883f2a1)
#22 0x000000000798bb3a clang::Sema::SubstDecl(clang::Decl*, clang::DeclContext*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x798bb3a)
#23 0x00000000078f4e88 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformDeclStmt(clang::DeclStmt*) SemaTemplateInstantiate.cpp:0:0
#24 0x000000000793d065 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCompoundStmt(clang::CompoundStmt*, bool) SemaTemplateInstantiate.cpp:0:0
#25 0x0000000007946464 clang::Sema::SubstStmt(clang::Stmt*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7946464)
#26 0x00000000079e4cfc clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x79e4cfc)
#27 0x00000000079e2f66 clang::Sema::PerformPendingInstantiations(bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x79e2f66)
#28 0x0000000006f45d02 clang::Sema::ActOnEndOfTranslationUnitFragment(clang::TUFragmentKind) (.part.0) Sema.cpp:0:0
#29 0x0000000006f4609d clang::Sema::ActOnEndOfTranslationUnit() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6f4609d)
#30 0x0000000006dab24a clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6dab24a)
#31 0x0000000006d8c05a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6d8c05a)
#32 0x0000000004fe80e8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4fe80e8)
#33 0x0000000005301875 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5301875)
#34 0x000000000528164e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x528164e)
#35 0x00000000053fe5dd clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x53fe5dd)
#36 0x0000000000ddc952 cc1_main(llvm::ArrayRef, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xddc952)
#37 0x0000000000dd328a ExecuteCC1Tool(llvm::SmallVectorImpl&, llvm::ToolContext const&, llvm::IntrusiveRefCntPtr) driver.cpp:0:0
#38 0x0000000000dd340d int llvm::function_ref&)>::callback_fn&)>(long, llvm::SmallVectorImpl&) driver.cpp:0:0
#39 0x0000000005051819 void llvm::function_ref::callback_fn>, std::__cxx11::basic_string, std::allocator>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#40 0x0000000004423af4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4423af4)
#41 0x0000000005051e46 clang::driver::CC1Command::Execute(llvm::ArrayRef>, std::__cxx11::basic_string, std::allocator>*, bool*) const (.part.0) Job.cpp:0:0
#42 0x0000000005010cc2 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5010cc2)
#43 0x0000000005011c6e clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5011c6e)
#44 0x00000000050198c5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x50198c5)
#45 0x0000000000dd8cb4 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdd8cb4)
#46 0x0000000000c8ff1a main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc8ff1a)
#47 0x0000744650c29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#48 0x0000744650c29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#49 0x0000000000dd2d25 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xdd2d25)
clang++: error: clang frontend command failed due to signal (use -v to see invocation)
Compiler returned: 134
```