Warn by default on unused mutable variables #5966
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Needs a rebase (sorry!) |
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@catamorphism, no problem, should be rebased now |
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I think that the r+ accidentally went on the first instead of the last commit, but I went ahead and addressed your comments anyway (hopefully the comments in the code clarify a bit more). |
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Yup, I made a mistake and r+'d the wrong commit. Thanks for the added comments, they're helpful! (And I r+'d the right one now.) |
bors
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Apr 22, 2013
Closes #3083. This takes a similar approach to #5797 where a set is present on the `tcx` of used mutable definitions. Everything is by default warned about, and analyses must explicitly add mutable definitions to this set so they're not warned about. Most of this was pretty straightforward, although there was one caveat that I ran into when implementing it. Apparently when the old modes are used (or maybe `legacy_modes`, I'm not sure) some different code paths are taken to cause spurious warnings to be issued which shouldn't be issued. I'm not really sure how modes even worked, so I was having a lot of trouble tracking this down. I figured that because they're a legacy thing that I'd just de-mode the compiler so that the warnings wouldn't be a problem anymore (or at least for the compiler). Other than that, the entire compiler compiles without warnings of unused mutable variables. To prevent bad warnings, #5965 should be landed (which in turn is waiting on #5963) before landing this. I figured I'd stick it out for review anyway though.
flip1995
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Aug 28, 2020
Corrects the float_equality_without_abs lint Fixes an issue in the `float_equality_without_abs` lint. The lint suggestion was configured in a way that it lints the whole error and not just the subtraction part. In the current configuration the lint would suggest to change the expression in a wrong way, e.g. ```rust let _ = (a - b) < f32::EPSILON; // before let _ = (a - b).abs(); // after ``` This was dicovered by @flip1995. (See discussion of PR rust-lang#5952). Also the suggestion is now formatted via `utils::sugg`. changelog: none
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Closes #3083.
This takes a similar approach to #5797 where a set is present on the
tcxof used mutable definitions. Everything is by default warned about, and analyses must explicitly add mutable definitions to this set so they're not warned about.Most of this was pretty straightforward, although there was one caveat that I ran into when implementing it. Apparently when the old modes are used (or maybe
legacy_modes, I'm not sure) some different code paths are taken to cause spurious warnings to be issued which shouldn't be issued. I'm not really sure how modes even worked, so I was having a lot of trouble tracking this down. I figured that because they're a legacy thing that I'd just de-mode the compiler so that the warnings wouldn't be a problem anymore (or at least for the compiler).Other than that, the entire compiler compiles without warnings of unused mutable variables. To prevent bad warnings, #5965 should be landed (which in turn is waiting on #5963) before landing this. I figured I'd stick it out for review anyway though.