Hover crash while printing expr with recovery-asts

[kadircet]

void foo() {
  int x;
  int width = x;
  const int test[1] = {
      wi^dth,
      1,
  };
}

Triggering hover on ^ results in a crash, while it doesn't when triggered with -recovery-ast=0

clangd: /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/Support/Casting.h:104: static bool llvm::isa_impl_cl<clang::ImplicitValueInitExpr, const clang::Expr *>::doit(const From *) [To = clang::ImplicitValueInitExpr, From = const clang::Expr *]: Assertion `Val && "isa<> used on a null pointer"' failed.
 #0 0x00000000004f1324 PrintStackTrace /usr/local/google/home/kadircet/repos/llvm/llvm/lib/Support/Unix/Signals.inc:564:13
 #1 0x00000000004f1324 PrintStackTraceSignalHandler(void*) /usr/local/google/home/kadircet/repos/llvm/llvm/lib/Support/Unix/Signals.inc:624:3
 #2 0x00000000004ef01c llvm::sys::RunSignalHandlers() /usr/local/google/home/kadircet/repos/llvm/llvm/lib/Support/Signals.cpp:69:18
 #3 0x00000000004f152c SignalHandler(int) /usr/local/google/home/kadircet/repos/llvm/llvm/lib/Support/Unix/Signals.inc:396:3
 #4 0x00007f6b740aa110 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14110)
 #5 0x00007f6b72625761 raise /build/glibc-M65Gwz/glibc-2.30/signal/../sysdeps/unix/sysv/linux/raise.c:51:1
 #6 0x00007f6b7260f55b abort /build/glibc-M65Gwz/glibc-2.30/stdlib/abort.c:81:7
 #7 0x00007f6b7260f42f get_sysdep_segment_value /build/glibc-M65Gwz/glibc-2.30/intl/loadmsgcat.c:509:8
 #8 0x00007f6b7260f42f _nl_load_domain /build/glibc-M65Gwz/glibc-2.30/intl/loadmsgcat.c:970:34
 #9 0x00007f6b7261e092 (/lib/x86_64-linux-gnu/libc.so.6+0x34092)
#10 0x00000000006c1139 (/usr/local/google/home/kadircet/repos/llvm/build/bin/clangd+0x6c1139)
#11 0x00000000006c0356 (anonymous namespace)::ArrayExprEvaluator::VisitInitListExpr(clang::InitListExpr const*, clang::QualType) /usr/local/google/home/kadircet/repos/llvm/clang/lib/AST/ExprConstant.cpp:10037:7
#12 0x000000000065ec45 Evaluate(clang::APValue&, (anonymous namespace)::EvalInfo&, clang::Expr const*) /usr/local/google/home/kadircet/repos/llvm/clang/lib/AST/ExprConstant.cpp:13958:9
#13 0x0000000000661883 EvaluateAsRValue((anonymous namespace)::EvalInfo&, clang::Expr const*, clang::APValue&) /usr/local/google/home/kadircet/repos/llvm/clang/lib/AST/ExprConstant.cpp:14037:9
#14 0x000000000065be2d EvaluateAsRValue /usr/local/google/home/kadircet/repos/llvm/clang/lib/AST/ExprConstant.cpp:14094:10
#15 0x000000000065be2d clang::Expr::EvaluateAsRValue(clang::Expr::EvalResult&, clang::ASTContext const&, bool) const /usr/local/google/home/kadircet/repos/llvm/clang/lib/AST/ExprConstant.cpp:14140:10
#16 0x0000000000acd161 clang::clangd::(anonymous namespace)::printExprValue[abi:cxx11](clang::Expr const*, clang::ASTContext const&) /usr/local/google/home/kadircet/repos/llvm/clang-tools-extra/clangd/Hover.cpp:340:68
#17 0x0000000000ac7f54 printExprValue /usr/local/google/home/kadircet/repos/llvm/clang-tools-extra/clangd/Hover.cpp:363:22
#18 0x0000000000ac7f54 clang::clangd::getHover(clang::clangd::ParsedAST&, clang::clangd::Position, clang::format::FormatStyle, clang::clangd::SymbolIndex const*) /usr/local/google/home/kadircet/repos/llvm/clang-tools-extra/clangd/Hover.cpp:832:23
#19 0x0000000000a54cd6 Expected<llvm::Optional<clang::clangd::HoverInfo> > /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/Support/Error.h:482:9
#20 0x0000000000a54cd6 operator() /usr/local/google/home/kadircet/repos/llvm/clang-tools-extra/clangd/ClangdServer.cpp:621:8
#21 0x0000000000a54cd6 void llvm::detail::UniqueFunctionBase<void, llvm::Expected<clang::clangd::InputsAndAST> >::CallImpl<clang::clangd::ClangdServer::findHover(llvm::StringRef, clang::clangd::Position, llvm::unique_function<void (llvm::Expected<llvm::Optional<clang::clangd::HoverInfo> >)>)::$_12>(void*, llvm::Expected<clang::clangd::InputsAndAST>&) /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/ADT/FunctionExtras.h:195:12
#22 0x0000000000b56fe1 operator() /usr/local/google/home/kadircet/repos/llvm/clang-tools-extra/clangd/TUScheduler.cpp:0:0
#23 0x0000000000b56fe1 void llvm::detail::UniqueFunctionBase<void>::CallImpl<clang::clangd::(anonymous namespace)::ASTWorker::runWithAST(llvm::StringRef, llvm::unique_function<void (llvm::Expected<clang::clangd::InputsAndAST>)>, clang::clangd::TUScheduler::ASTActionInvalidation)::$_1>(void*) /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/ADT/FunctionExtras.h:195:12
#24 0x0000000000b4d327 reset /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/ADT/Optional.h:64:9
#25 0x0000000000b4d327 ~OptionalStorage /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/ADT/Op

[hokein]

InitListExpr is a tricky AST node, it could has two forms, syntactic and semantic. RAV returns a syntactic one, but we must feed a semantic one to EvaluateAsRValue.

reproduce with a valid code:

struct Foo {
  int a[10];
};
 constexpr Foo k2 = {
   ^{1}
};

preparing a fix.