[clang] Assertion `NameInfo.getName()' failed.

Reproducer:
https://godbolt.org/z/84zTjzsrM
```cpp
template class C> struct S {
friend C();
}
```

Backtrace:
```console
clang++: /root/llvm-project/llvm/tools/clang/lib/Sema/SemaDeclCXX.cpp:18581: clang::NamedDecl* clang::Sema::ActOnFriendFunctionDecl(clang::Scope*, clang::Declarator&, clang::MultiTemplateParamsArg): Assertion `NameInfo.getName()' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and dumped files.
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. :2:13: current parser token ';'
2. :1:32: parsing struct/union/class body 'S'
#0 0x000000000449a958 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x449a958)
#1 0x0000000004497bb4 llvm::sys::RunSignalHandlers() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4497bb4)
#2 0x00000000044981ec llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x44981ec)
#3 0x00000000043d5018 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
#4 0x00007825be645330 (/lib/x86_64-linux-gnu/libc.so.6+0x45330)
#5 0x00007825be69ec0c pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x9ec0c)
#6 0x00007825be64527e raise (/lib/x86_64-linux-gnu/libc.so.6+0x4527e)
#7 0x00007825be6288ff abort (/lib/x86_64-linux-gnu/libc.so.6+0x288ff)
#8 0x00007825be62881b (/lib/x86_64-linux-gnu/libc.so.6+0x2881b)
#9 0x00007825be63b517 (/lib/x86_64-linux-gnu/libc.so.6+0x3b517)
#10 0x00000000072b1e5f clang::Sema::ActOnFriendFunctionDecl(clang::Scope*, clang::Declarator&, llvm::MutableArrayRef) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x72b1e5f)
#11 0x0000000006e6dfc2 clang::Parser::ParseCXXClassMemberDeclaration(clang::AccessSpecifier, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::ParsingDeclRAIIObject*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6e6dfc2)
#12 0x0000000006e6f22f clang::Parser::ParseCXXClassMemberDeclarationWithPragmas(clang::AccessSpecifier&, clang::ParsedAttributes&, clang::TypeSpecifierType, clang::Decl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6e6f22f)
#13 0x0000000006e6f7ac clang::Parser::ParseCXXMemberSpecification(clang::SourceLocation, clang::SourceLocation, clang::ParsedAttributes&, unsigned int, clang::Decl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6e6f7ac)
#14 0x0000000006e72200 clang::Parser::ParseClassSpecifier(clang::tok::TokenKind, clang::SourceLocation, clang::DeclSpec&, clang::Parser::ParsedTemplateInfo&, clang::AccessSpecifier, bool, clang::Parser::DeclSpecContext, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6e72200)
#15 0x0000000006e40d7c clang::Parser::ParseDeclarationSpecifiers(clang::DeclSpec&, clang::Parser::ParsedTemplateInfo&, clang::AccessSpecifier, clang::Parser::DeclSpecContext, clang::LateParsedAttrList*, clang::ImplicitTypenameContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6e40d7c)
#16 0x0000000006f19949 clang::Parser::ParseDeclarationAfterTemplate(clang::DeclaratorContext, clang::Parser::ParsedTemplateInfo&, clang::ParsingDeclRAIIObject&, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6f19949)
#17 0x0000000006f27217 clang::Parser::ParseTemplateDeclarationOrSpecialization(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (.part.0) ParseTemplate.cpp:0:0
#18 0x0000000006f275ca clang::Parser::ParseDeclarationStartingWithTemplate(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6f275ca)
#19 0x0000000006e54d00 clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6e54d00)
#20 0x0000000006e0b630 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6e0b630)
#21 0x0000000006e0c545 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6e0c545)
#22 0x0000000006e0c930 clang::Parser::ParseFirstTopLevelDecl(clang::OpaquePtr&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6e0c930)
#23 0x0000000006de88ec clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6de88ec)
#24 0x0000000004fad878 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4fad878)
#25 0x00000000052cde58 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x52cde58)
#26 0x000000000525b95d clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x525b95d)
#27 0x00000000053a262d clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x53a262d)
#28 0x0000000000d8d8ac cc1_main(llvm::ArrayRef, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd8d8ac)
#29 0x0000000000d845aa ExecuteCC1Tool(llvm::SmallVectorImpl&, llvm::ToolContext const&, llvm::IntrusiveRefCntPtr) driver.cpp:0:0
#30 0x0000000000d8472d int llvm::function_ref&)>::callback_fn&)>(long, llvm::SmallVectorImpl&) driver.cpp:0:0
#31 0x0000000005021359 void llvm::function_ref::callback_fn>, std::__cxx11::basic_string, std::allocator>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#32 0x00000000043d5414 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43d5414)
#33 0x0000000005021ec5 clang::driver::CC1Command::Execute(llvm::ArrayRef>, std::__cxx11::basic_string, std::allocator>*, bool*) const (.part.0) Job.cpp:0:0
#34 0x0000000004fe02f2 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4fe02f2)
#35 0x0000000004fe4c57 clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4fe4c57)
#36 0x0000000004fef1b5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4fef1b5)
#37 0x0000000000d89d9a clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd89d9a)
#38 0x0000000000cc792a main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xcc792a)
#39 0x00007825be62a1ca (/lib/x86_64-linux-gnu/libc.so.6+0x2a1ca)
#40 0x00007825be62a28b __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2a28b)
#41 0x0000000000d83f55 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd83f55)
clang++: error: clang frontend command failed due to signal (use -v to see invocation)
Program terminated with signal SIGABRT (6)
Compiler returned: 134
```

Reproduce the crash with the C++ snippet from the issue, then inspect llvm/tools/clang/lib/Sema/SemaDeclCXX.cpp at Sema::ActOnFriendFunctionDecl, identified by the backtrace. Trace how the friend declaration reaches the failing NameInfo assertion; done means the reproducer no longer aborts and produces a valid diagnostic or accepted result.

Written by the indexing model from the issue text.