fix numeric promotion for eq/ne comparisons #424
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The non-equality comparisons (`<`, `<=`, `>`, `>=`) require numeric promotion always, but equality comparisons (`==`, `!=`) only require it if at least one argument is numeric type (that is, primitive but not `boolean`). If both arguments are not numeric types, no numeric promotion should happen. We previously guarded against that in a naive way: the `numericPromotion()` method returned early when both operands were of the same type after unboxing. This leads to incorrect conversion in case of equality comparisons on primitive wrapper types (and may lead to NPE at runtime). This commit adds proper guard to the appropriate place. Note that there are other occurences of `numericPromotion()` which are not guarded by `numericPromotionRequired()`. These are in `BinOp` and in `Cmp`, where on both places the operation is always numeric and so always requires numeric promotion.
dmlloyd
approved these changes
Jun 17, 2025
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The non-equality comparisons (
<,<=,>,>=) require numeric promotion always, but equality comparisons (==,!=) only require it if at least one argument is numeric type (that is, primitive but notboolean). If both arguments are not numeric types, no numeric promotion should happen.We previously guarded against that in a naive way: the
numericPromotion()method returned early when both operands were of the same type after unboxing. This leads to incorrect conversion in case of equality comparisons on primitive wrapper types (and may lead to NPE at runtime). This commit adds proper guard to the appropriate place.Note that there are other occurences of
numericPromotion()which are not guarded bynumericPromotionRequired(). These are inBinOpand inCmp, where on both places the operation is always numeric and so always requires numeric promotion.