[MILR][NFC] Silence clang-tidy warning in AffineOps.cpp

[bondhugula]

Summary

Silence clang-tidy warning in AffineOps.cpp due to the inability to see
through the typeswitch. NFC.

[bondhugula]

Tweak comment.

[rriddle]

What compiler does this fire on?

[bondhugula]

In D106125#2897120, @rriddle wrote:

What compiler does this fire on?

This from clangd using:

• Clang version: clang version 10.0.0 (https://github.com/ycm-core/llvm 038587147cf2f97d1c3e677042f69560c65b5bea)

[rriddle]

That is surprising. I would have expected this to fire in more cases.

mlir/lib/Dialect/Affine/IR/AffineOps.cpp

111

[rriddle]

mlir/lib/Dialect/Affine/IR/AffineOps.cpp

112–113

Is the template here really necessary? (I wonder if the warning would be fixed by removing it)

This function should also be marked static.

[bondhugula]

Address review comments.

mlir/lib/Dialect/Affine/IR/AffineOps.cpp

112–113

The template <> isn't necessary here but is perhaps there for better readability as it indicates an explicit specialization for the function template above. The warning isn't getting fixed by removing it. Marked it static as well.

[bondhugula]

Put back template <> instead of static since the latter doesn't help with the warning.

mlir/lib/Dialect/Affine/IR/AffineOps.cpp

if (!remainsLegalAfterInline(
           symbolOperands, src, dest, mapping,
           static_cast<bool (*)(Value, Region *)>(isValidSymbol)))
     return false;
   return true;
 }
 
 /// Checks if an affine apply operation remains legal after inlining from `src`
 /// to `dest`.
+//  Use "unused attribute" marker to silence clang-tidy warning stemming from
+//  the inability to see through "llvm::TypeSwitch".
 template <>
-bool remainsLegalAfterInline(AffineApplyOp op, Region *src, Region *dest,
-                             const BlockAndValueMapping &mapping) {
+bool LLVM_ATTRIBUTE_UNUSED
+remainsLegalAfterInline(AffineApplyOp op, Region *src, Region *dest,
   // If it's a valid dimension, we need to check that it remains so.
   if (isValidDim(op.getResult(), src))
     return remainsLegalAfterInline(
         op.getMapOperands(), src, dest, mapping,
         static_cast<bool (*)(Value, Region *)>(isValidDim));
 
   // Otherwise it must be a valid symbol, check that it remains so.
   return remainsLegalAfterInline(