[Lldb-commits] [clang] [lldb] [Clang][LLDB] Refactor trap reason demangling out of LLDB and into Clang (PR #165996)

[Dan Liew via lldb-commits]

================
@@ -378,3 +379,31 @@ clang::CreateLLVMCodeGen(DiagnosticsEngine &Diags, llvm::StringRef ModuleName,
                                HeaderSearchOpts, PreprocessorOpts, CGO, C,
                                CoverageInfo);
 }
+
+namespace clang {
+namespace CodeGen {
+std::optional<std::pair<StringRef, StringRef>>
+DemangleTrapReasonInDebugInfo(StringRef FuncName) {
+  static auto TrapRegex =
+      llvm::Regex(llvm::formatv("^{0}\\$(.*)\\$(.*)$", ClangTrapPrefix).str());
+  llvm::SmallVector<llvm::StringRef, 3> Matches;
+  std::string *ErrorPtr = nullptr;
+#ifndef NDEBUG
+  std::string Error;
+  ErrorPtr = &Error;
+#endif
+  if (!TrapRegex.match(FuncName, &Matches, ErrorPtr)) {
+    assert(ErrorPtr && ErrorPtr->empty() && "Invalid regex pattern");
+    return {};
+  }
+
+  if (Matches.size() != 3) {
+    assert(0 && "Expected 3 matches from Regex::match");
----------------
delcypher wrote:

I don't know how it would be possible to assert here unless the `llvm::Regex` behavior changed. If the pattern matched there should be `3` matches exactly. If the behavior of `llvm::Regex` did change this seems like something we should catch with an assert rather than silently ignoring. Even if the mangling scheme used in the debug info did change in a newer LLDB I think this code in an older LLDB would:

* Not match the regex pattern at all and so we fail to extract the trap reason without asserting.
* Does match the regex but the category and message strings don't contain the correct contents. While not ideal in this case we still wouldn't assert. If we did change the mangling scheme we probably would try to avoid doing it this way because the change to the mangling scheme would not be backwards compatible.

https://github.com/llvm/llvm-project/pull/165996