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Do not suggest compatible variants inside macro #142611

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13 changes: 9 additions & 4 deletions compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2409,16 +2409,21 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let (open, close) = match ctor_kind {
Some(CtorKind::Fn) => ("(".to_owned(), ")"),
None => (format!(" {{ {field_name}: "), " }"),

Some(CtorKind::Const) => unreachable!("unit variants don't have fields"),
};

// Suggest constructor as deep into the block tree as possible.
// This fixes https://github.com/rust-lang/rust/issues/101065,
// and also just helps make the most minimal suggestions.
// Find the deepest expression in the block tree while staying within the same
// context. This ensures that suggestions point to user-visible code
// rather than macro-expanded internal code.
//
// For example, with `println!("A")`, we want to suggest wrapping the entire
// `println!("A")` call, not some internal macro-generated code.
// See #101065, #142359
let mut expr = expr;
while let hir::ExprKind::Block(block, _) = &expr.kind
&& let Some(expr_) = &block.expr
// Only traverse blocks in same context
&& expr_.span.eq_ctxt(expr.span)
Comment on lines 2423 to +2426
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This time, I find the deepest expression in the block tree while staying within the same context. This ensures that suggestions point to user-visible code.

{
expr = expr_
}
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
// Make sure we don't suggest compatible variants inside macro. (issue #142359)
use std::ops::ControlFlow;

fn main(){
let x: Result<i32, i32> = Err(1);

let v= match x {
Err(r) => ControlFlow::Break(r),
Ok(r) => { println!("A")} //~ ERROR `match` arms have incompatible types [E0308]
};
}
Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
error[E0308]: `match` arms have incompatible types
--> $DIR/suggest-compatible-variants-macro-issue-142359.rs:9:20
|
LL | let v= match x {
| ____________-
LL | | Err(r) => ControlFlow::Break(r),
| | --------------------- this is found to be of type `ControlFlow<i32, _>`
LL | | Ok(r) => { println!("A")}
| | ^^^^^^^^^^^^^ expected `ControlFlow<i32, _>`, found `()`
LL | | };
| |_____- `match` arms have incompatible types
|
= note: expected enum `ControlFlow<i32, _>`
found unit type `()`
= note: this error originates in the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
help: try wrapping the expression in `std::ops::ControlFlow::Continue`
|
LL | Ok(r) => std::ops::ControlFlow::Continue({ println!("A")})
| ++++++++++++++++++++++++++++++++ +

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0308`.
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