[clang][Parse] Remove constant expression from if condition

[tbaeder]

Summary

MaybeTypeCast here is not a variable, it's an enum member with value 1.

I'm just not sure if this should be using isTypeCast instead or not. Let's see what the CI says.

[aaron.ballman]

This code was introduced in https://github.com/llvm/llvm-project/commit/5a5319062300166a747807339349766341a2c2b2 and does not appear to have had precommit review (that I could find). It was resolving https://bugs.llvm.org/show_bug.cgi?id=23101, and the last comment on that issue suggests this was intending to look at isTypeCast.

I expect precommit CI will not care about the removal because it is a no-op change.

[aaron.ballman]

Precommit CI found that this change breaks clang/test/Sema/PR28181.c which was introduced to fix https://bugs.llvm.org/show_bug.cgi?id=28181 which was a regression caused by https://github.com/llvm/llvm-project/commit/5a5319062300166a747807339349766341a2c2b2

[tbaeder]

Yeah, just removing the MaybeTypeCast worked, but switching to isTypeCast doens't.

[aaron.ballman]

In D138289#3943090, @tbaeder wrote:

Yeah, just removing the MaybeTypeCast worked, but switching to isTypeCast doens't.

I think for now we can remove the MaybeTypeCast entirely. We only set isTypeCast once we *know* we're dealing with a type cast, and this is about typo correction where we probably don't know what we're dealing with. Given that it's a no-op change to do that, removing it leaves us in no worse shape than we were before.

clang/lib/Parse/ParseExpr.cpp

if (ErrorFound) {
       Result = Actions.ActOnOMPArrayShapingExpr(
           Result.get(), OpenLoc, RParenLoc, OMPDimensions, OMPBracketsRanges);
     }
     return Result;
   } else {
     InMessageExpressionRAIIObject InMessage(*this, false);
 
     Result = ParseExpression(MaybeTypeCast);
-    if (!getLangOpts().CPlusPlus && MaybeTypeCast && Result.isUsable()) {
+    if (!getLangOpts().CPlusPlus && isTypeCast && Result.isUsable()) {
       // Correct typos in non-C++ code earlier so that implicit-cast-like
       // expressions are parsed correctly.
       Result = Actions.CorrectDelayedTyposInExpr(Result);
     }
 
     if (ExprType >= FoldExpr && isFoldOperator(Tok.getKind()) &&
         NextToken().is(tok::ellipsis)) {
       ExprType = FoldExpr;