Mediocre error message for f32/f64 ambiguity #47759

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1. emilyalbini

   added

   C-enhancementCategory: An issue proposing an enhancement or a PR with one.Category: An issue proposing an enhancement or a PR with one.

   A-diagnosticsArea: Messages for errors, warnings, and lintsArea: Messages for errors, warnings, and lints

   T-compilerRelevant to the compiler team, which will review and decide on the PR/issue.Relevant to the compiler team, which will review and decide on the PR/issue.

   A-inferenceArea: Type inferenceArea: Type inference

   on Jan 25, 2018
2. kennytm commented on Jan 25, 2018

   

   kennytm

   on Jan 25, 2018

   Last edited by kennytm

   Member

   More actions

   Note that type inference cannot figure out 2.0 is an f64 just by x * 2.0.exp() because this is perfectly valid.

   struct Foo;
   trait Wat {
       fn exp(self) -> Foo;
   }
   impl Wat for f32 {
       fn exp(self) -> Foo { Foo }
   }
   impl std::ops::Mul<Foo> for f64 {
       type Output = &'static str;
       fn mul(self, _: Foo) -> &'static str {
           "wat"
       }
   }
   
   fn main() {
       let _ = |x: f64| x * 2.0.exp();
       //let _ = |x: f64| x * 2.0f64.exp();
   }
3. nieksand commented on Jan 25, 2018

   

   nieksand

   on Jan 25, 2018

   ContributorAuthor

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   Yipes. Inference is definitely out.
4. Centril

   added a commit that references this issue on Apr 10, 2020

   Rollup merge of rust-lang#70784 - estebank:suggest-type-fundamental-m…

   ...

   This issue will close once commit dff5a11 is merged into the 'master' branch.

   dff5a11
5. bors

   closed this as completedin a2a65a8on Apr 10, 2020