[clang] [CIR] Fix a crash when source location is unknown (PR #185059)

[Erich Keane via cfe-commits]

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@@ -113,9 +113,14 @@ mlir::Location CIRGenFunction::getLoc(SourceLocation srcLoc) {
     return mlir::FileLineColLoc::get(builder.getStringAttr(filename),
                                      pLoc.getLine(), pLoc.getColumn());
   }
-  // Do our best...
+  // We expect to have a currSrcLoc set, so we assert here, but it isn't
+  // critical for the correctness of compilation, so in non-assert builds
+  // we fallback on using an unknown location.
   assert(currSrcLoc && "expected to inherit some source location");
-  return *currSrcLoc;
+  if (currSrcLoc)
+    return *currSrcLoc;
+  // We're brave, but time to give up.
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erichkeane wrote:

I see this comment came from below, but lol :D 

https://github.com/llvm/llvm-project/pull/185059