[clang] Add error check for HeuristicResolver (PR #155561)

[Nathan Ridge via cfe-commits]

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@@ -41,7 +61,16 @@ template <typename InputNode, typename ParamT, typename InputMatcher,
           typename... OutputMatchers>
 void expectResolution(llvm::StringRef Code, ResolveFnT<ParamT> ResolveFn,
                       const InputMatcher &IM, const OutputMatchers &...OMS) {
+  llvm::SmallSet<unsigned int, 16> IgnoredDiagnostics{};
   auto TU = tooling::buildASTFromCodeWithArgs(Code, {"-std=c++23"});
+
+  for (auto D = TU->stored_diag_begin(), DEnd = TU->stored_diag_end();
+       D != DEnd; ++D) {
+    EXPECT_TRUE(D->getLevel() < DiagnosticsEngine::Warning ||
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HighCommander4 wrote:

Are you intentionally disallowing warnings by default?

(I don't particularly feel strongly either way, but in the clangd test infra the check is `level < Error`, so I was just curious if you're deliberately being stricter.)

https://github.com/llvm/llvm-project/pull/155561