Don't suggest incorrect syntax

[estebank]

Fix #51634.

[rust-highfive]

r? @michaelwoerister

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[oli-obk]

We probably get the same bad suggestion when creating the binding via a macro that takes the name of the local to be created via an ident fragment.

[estebank]

Can you provide a repro case? I'll see if I have any way of differentiate them (other than checking the span context).

[oli-obk]

somewhat xD I found other stuff:

    let x: _ = 42;
    x.pow(2);

help: you must specify a type for this binding, like `i32`
  |
8 |     let x: i32: _ = 42;
  |         ^^^^^^

and

macro_rules! foo {
    ($ident:ident) => { let $ident = 42; }
}

fn main() {
    foo!(bar);
    bar.pow(2);
}

suggests to modify a macro (which might be not from this crate)

help: you must specify a type for this binding, like `i32`
  |
2 |     ($ident:ident) => { let $ident: i32 = 42; }
  |                             ^^^^^^^^^^^ 

[estebank]

@oli-obk as is, on external macros, the suggestion uses the compiled macro output:

error[E0689]: can't call method `pow` on ambiguous numeric type `{integer}`
  --> $DIR/method-on-ambiguous-numeric-type.rs:40:9
   |
LL |     bar.pow(2);
   |         ^^^
help: you must specify a type for this binding, like `i32`
   |
LL | ( $ ident : ident ) => { let $ ident: i32 = 42 ; }
   |                              ^^^^^^^^^^^^

[estebank]

Changed to account for both of the presented cases.

error[E0689]: can't call method `pow` on ambiguous numeric type `{integer}`
  --> $DIR/method-on-ambiguous-numeric-type.rs:40:9
   |
LL |     mac!(bar);
   |     ---------- you must specify a type for this binding, like `i32`
LL |     bar.pow(2);
   |         ^^^
   |
   = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

[oli-obk]

You match on filename above toget this bool. Can you just match on it directly here?

[estebank]

Done.

[oli-obk]

@bors r+

[bors]

📌 Commit cc0ab82 has been approved by oli-obk

[bors]

⌛ Testing commit cc0ab82 with merge 8f02447...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: oli-obk
Pushing 8f02447 to master...