Document traits in std::num (#7511) #13470
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bors
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flip1995
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The `identity_op` lint was suggesting code fixes that resulted in incorrect or broken code, due to missing parenthesis in the fix that changed the semantics of the code. For a binary expression, `left op right`, if the `left` was redundant, it would check if the right side needed parenthesis, but if the `right` was redundant, it would just assume that the left side did not need parenthesis. This can result in either rustfix generating broken code and failing, or code that has different behavior than before the fix. e.g. `-(x + y + 0)` would turn into `-x + y`, changing the behavior, and `1u64 + (x + y + 0i32) as u64` where `x: i32` and `y: i32` would turn into `1u64 + x + y as u64`, creating broken code where `x` cannot be added to the other values, as it was never cast to `u64`. This commit fixes both of these cases by always checking the non-redundant child of a binary expression for needed parenthesis, and makes it so if we need parenthesis, but they already exist, we don't add any redundant ones. Fixes rust-lang#13470
flip1995
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Nov 14, 2024
The `identity_op` lint was suggesting code fixes that resulted in incorrect or broken code, due to missing parenthesis in the fix that changed the semantics of the code. For a binary expression, `left op right`, if the `left` was redundant, it would check if the right side needed parenthesis, but if the `right` was redundant, it would just assume that the left side did not need parenthesis. This can result in rustfix generating broken code and failing, or generating code that has different behavior than before the fix. e.g. `-(x + y + 0)` would turn into `-x + y`, changing the behavior, and `1u64 + (x + y + 0i32) as u64` where `x: i32` and `y: i32` would turn into `1u64 + x + y as u64`, creating an error where `x` cannot be added to the other values, as it was never cast to `u64`. This commit fixes both of these problems by always checking the non-redundant child of a binary expression for needed parenthesis. fixes rust-lang#13470 changelog: [`identity_op`]: Fix suggested code that is broken or has changed behavior
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See #7511