give better suggestion when matching a const range
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@ -772,12 +772,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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);
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}
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_ => {
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let const_def_id = match pat_ty.kind() {
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let (type_def_id, item_def_id) = match pat_ty.kind() {
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Adt(def, _) => match res {
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Res::Def(DefKind::Const, _) => Some(def.did),
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_ => None,
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Res::Def(DefKind::Const, def_id) => (Some(def.did), Some(def_id)),
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_ => (None, None),
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},
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_ => None,
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_ => (None, None),
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};
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let ranges = &[
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@ -788,11 +788,46 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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self.tcx.lang_items().range_inclusive_struct(),
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self.tcx.lang_items().range_to_inclusive_struct(),
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];
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if const_def_id != None && ranges.contains(&const_def_id) {
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let msg = "constants only support matching by type, \
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if you meant to match against a range of values, \
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consider using a range pattern like `min ..= max` in the match block";
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e.note(msg);
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if type_def_id != None && ranges.contains(&type_def_id) {
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let generic_message = match item_def_id {
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Some(def_id) => match self.tcx.hir().get_if_local(def_id) {
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Some(hir::Node::Item(hir::Item {
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kind: hir::ItemKind::Const(_, body_id),
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..
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})) => match self.tcx.hir().get(body_id.hir_id) {
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hir::Node::Expr(expr) => {
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if hir::is_range_literal(expr) {
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let span = self.tcx.hir().span(body_id.hir_id);
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if let Ok(snip) =
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self.tcx.sess.source_map().span_to_snippet(span)
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{
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e.span_suggestion_verbose(
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span,
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"you may want to move the range into the match block",
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snip,
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Applicability::MachineApplicable
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);
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false
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} else {
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true
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}
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} else {
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true
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}
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}
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_ => true,
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},
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_ => true,
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},
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_ => true,
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};
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if generic_message {
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let msg = "constants only support matching by type, \
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if you meant to match against a range of values, \
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consider using a range pattern like `min ..= max` in the match block";
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e.note(msg);
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}
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} else {
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let msg = "introduce a new binding instead";
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let sugg = format!("other_{}", ident.as_str().to_lowercase());
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@ -2,13 +2,18 @@
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#![allow(non_snake_case)]
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use std::ops::RangeInclusive;
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const RANGE: RangeInclusive<i32> = 0..=255;
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const RANGE2: RangeInclusive<i32> = panic!();
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fn main() {
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let n: i32 = 1;
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match n {
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RANGE => {}
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//~^ ERROR mismatched types
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RANGE2 => {}
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//~^ ERROR mismatched types
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_ => {}
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}
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}
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@ -1,5 +1,5 @@
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error[E0308]: mismatched types
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--> $DIR/issue-76191.rs:10:9
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--> $DIR/issue-76191.rs:13:9
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LL | const RANGE: RangeInclusive<i32> = 0..=255;
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| ------------------------------------------- constant defined here
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@ -14,8 +14,30 @@ LL | RANGE => {}
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= note: expected type `i32`
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found struct `RangeInclusive<i32>`
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help: you may want to move the range into the match block
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LL | const RANGE: RangeInclusive<i32> = 0..=255;
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| ^^^^^^^
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error[E0308]: mismatched types
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--> $DIR/issue-76191.rs:15:9
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LL | const RANGE2: RangeInclusive<i32> = panic!();
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| --------------------------------------------- constant defined here
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...
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LL | match n {
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| - this expression has type `i32`
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...
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LL | RANGE2 => {}
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| ^^^^^^
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| |
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| expected `i32`, found struct `RangeInclusive`
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| `RANGE2` is interpreted as a constant, not a new binding
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= note: expected type `i32`
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found struct `RangeInclusive<i32>`
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= note: constants only support matching by type, if you meant to match against a range of values, consider using a range pattern like `min ..= max` in the match block
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error: aborting due to previous error
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0308`.
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