[PATCH] D93822: [clang-tidy] Add check for implicit widening of multiplication result

[Roman Lebedev via Phabricator via cfe-commits]

lebedev.ri marked an inline comment as done.
lebedev.ri added a comment.

In D93822#2664157 <https://reviews.llvm.org/D93822#2664157>, @aaron.ballman wrote:

> The CI is showing build failures and there are some clang-tidy nits to be addressed as well.

Thank you for taking a look!



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Comment at: clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp:32
+  if (!BO || BO->getOpcode() != BO_Mul)
+    // FIXME: what about:  long r = int(x) + (int(y) * int(z));  ?
+    return nullptr;
----------------
aaron.ballman wrote:
> I think that could be handled in a follow-up if we find the need, WDYT?
Sure.


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Comment at: clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp:75
+  else if (Ty->isSignedIntegerType()) {
+    assert(ETy->isUnsignedIntegerType() &&
+           "Expected source type to be signed.");
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aaron.ballman wrote:
> Might be worth it to have tests around `signed char`, `unsigned char`, and `char` explicitly, as that gets awkward.
Are you asking for test coverage, or for explicit handling of those types?
I'll add tests.


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Comment at: clang/lib/AST/ASTContext.cpp:10158
+  if (const auto *ETy = T->getAs<EnumType>())
+    T = ETy->getDecl()->getIntegerType();
+
----------------
aaron.ballman wrote:
> This looks to be getting the same value as in the `getCorrespondingUnsignedType()` call?
Yep. Are both of them incorrect?
I'm not sure what should be returned here.


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Comment at: clang/lib/AST/ASTContext.cpp:10204
+    return SatLongFractTy;
+  default:
+    llvm_unreachable("Unexpected unsigned integer or fixed point type");
----------------
aaron.ballman wrote:
> It looks like `_ExtInt` is missing from both this function and the corresponding unsigned one.
Likewise, i'm not sure what should be returned for that.
Just the original `_ExtInt`?


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  https://reviews.llvm.org/D93822/new/

https://reviews.llvm.org/D93822