On May 15, 2012, at 4:10 PM, Richard Trieu <[email protected]> wrote:
> Add -Wunique-enum which will warn on enums with at least 2 elements such that
> all elements are the same value. This will catch enums such as:
>
> enum A {
> FIRST = 1,
> SECOND = 1
> };
Why do we need this warning? Personally, I can't recall having seen this be the
source of any bugs, and it's scope is so narrow that it doesn't seem worth
adding.
As for the actual patch…
+def warn_identical_enum_values : Warning<
+ "all elements of %select{anonymous enum|%1}0 have value %2">,
+ InGroup<DiagGroup<"unique-enum">>, DefaultIgnore;
+
Default-ignore warnings are always a red flag. If this warning is important, it
should be on by default. If it's not important, we shouldn't add it.
+ // Keep track of whther all the elements have the same value.
+ bool AllElementsEqual = true;
+ llvm::APSInt LastVal;
Typo "whther".
+ // Keep track of whether every enum element is the same value.
+ if (AllElementsEqual && i > 0) {
+ if (InitVal.getBitWidth() > LastVal.getBitWidth())
+ AllElementsEqual = InitVal == LastVal.extend(InitVal.getBitWidth());
+ else if (InitVal.getBitWidth() < LastVal.getBitWidth())
+ AllElementsEqual = InitVal.extend(LastVal.getBitWidth()) == LastVal;
+ else
+ AllElementsEqual = InitVal == LastVal;
+ }
+ LastVal = InitVal;
+
If you did this in the loop below, where we adjust the initializer values to
all have the same size/# of bits, it would be easier.
- Doug
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