Rollup merge of #64049 - estebank:if-else-type-err, r=Centril
Emit a single error on if expr with expectation and no else clause Fix https://github.com/rust-lang/rust/issues/60254. r? @Centril
This commit is contained in:
commit
4245be7fb3
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@ -112,19 +112,26 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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}
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self.diverges.set(pats_diverge);
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let arm_ty = self.check_expr_with_expectation(&arm.body, expected);
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let arm_ty = if source_if && if_no_else && i != 0 && self.if_fallback_coercion(
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expr.span,
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&arms[0].body,
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&mut coercion,
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) {
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tcx.types.err
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} else {
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// Only call this if this is not an `if` expr with an expected type and no `else`
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// clause to avoid duplicated type errors. (#60254)
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self.check_expr_with_expectation(&arm.body, expected)
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};
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all_arms_diverge &= self.diverges.get();
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let span = expr.span;
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if source_if {
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let then_expr = &arms[0].body;
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match (i, if_no_else) {
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(0, _) => coercion.coerce(self, &self.misc(span), &arm.body, arm_ty),
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(_, true) => self.if_fallback_coercion(span, then_expr, &mut coercion),
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(0, _) => coercion.coerce(self, &self.misc(expr.span), &arm.body, arm_ty),
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(_, true) => {} // Handled above to avoid duplicated type errors (#60254).
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(_, _) => {
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let then_ty = prior_arm_ty.unwrap();
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let cause = self.if_cause(span, then_expr, &arm.body, then_ty, arm_ty);
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let cause = self.if_cause(expr.span, then_expr, &arm.body, then_ty, arm_ty);
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coercion.coerce(self, &cause, &arm.body, arm_ty);
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}
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}
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@ -139,7 +146,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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// The reason for the first arm to fail is not that the match arms diverge,
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// but rather that there's a prior obligation that doesn't hold.
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0 => (arm_span, ObligationCauseCode::BlockTailExpression(arm.body.hir_id)),
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_ => (span, ObligationCauseCode::MatchExpressionArm {
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_ => (expr.span, ObligationCauseCode::MatchExpressionArm {
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arm_span,
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source: match_src,
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prior_arms: other_arms.clone(),
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@ -180,16 +187,19 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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}
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/// Handle the fallback arm of a desugared if(-let) like a missing else.
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///
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/// Returns `true` if there was an error forcing the coercion to the `()` type.
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fn if_fallback_coercion(
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&self,
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span: Span,
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then_expr: &'tcx hir::Expr,
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coercion: &mut CoerceMany<'tcx, '_, rustc::hir::Arm>,
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) {
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) -> bool {
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// If this `if` expr is the parent's function return expr,
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// the cause of the type coercion is the return type, point at it. (#25228)
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let ret_reason = self.maybe_get_coercion_reason(then_expr.hir_id, span);
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let cause = self.cause(span, ObligationCauseCode::IfExpressionWithNoElse);
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let mut error = false;
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coercion.coerce_forced_unit(self, &cause, &mut |err| {
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if let Some((span, msg)) = &ret_reason {
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err.span_label(*span, msg.as_str());
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@ -200,7 +210,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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}
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err.note("`if` expressions without `else` evaluate to `()`");
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err.help("consider adding an `else` block that evaluates to the expected type");
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error = true;
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}, ret_reason.is_none());
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error
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}
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fn maybe_get_coercion_reason(&self, hir_id: hir::HirId, span: Span) -> Option<(Span, String)> {
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@ -3,7 +3,6 @@ fn foo(bar: usize) -> usize {
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return 3;
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}
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//~^^^ ERROR if may be missing an else clause
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//~| ERROR mismatched types [E0308]
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}
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fn foo2(bar: usize) -> usize {
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@ -11,7 +10,6 @@ fn foo2(bar: usize) -> usize {
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return 3;
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};
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//~^^^ ERROR if may be missing an else clause
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//~| ERROR mismatched types [E0308]
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x
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}
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@ -20,7 +18,6 @@ fn foo3(bar: usize) -> usize {
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3
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}
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//~^^^ ERROR if may be missing an else clause
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//~| ERROR mismatched types [E0308]
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}
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fn foo_let(bar: usize) -> usize {
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@ -28,7 +25,6 @@ fn foo_let(bar: usize) -> usize {
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return 3;
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}
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//~^^^ ERROR if may be missing an else clause
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//~| ERROR mismatched types [E0308]
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}
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fn foo2_let(bar: usize) -> usize {
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@ -36,7 +32,6 @@ fn foo2_let(bar: usize) -> usize {
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return 3;
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};
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//~^^^ ERROR if may be missing an else clause
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//~| ERROR mismatched types [E0308]
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x
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}
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@ -45,7 +40,6 @@ fn foo3_let(bar: usize) -> usize {
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3
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}
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//~^^^ ERROR if may be missing an else clause
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//~| ERROR mismatched types [E0308]
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}
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// FIXME(60254): deduplicate first error in favor of second.
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@ -1,14 +1,3 @@
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error[E0308]: mismatched types
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--> $DIR/if-without-else-as-fn-expr.rs:2:5
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LL | / if bar % 5 == 0 {
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LL | | return 3;
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LL | | }
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| |_____^ expected usize, found ()
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= note: expected type `usize`
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found type `()`
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error[E0317]: if may be missing an else clause
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--> $DIR/if-without-else-as-fn-expr.rs:2:5
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@ -24,20 +13,8 @@ LL | | }
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= note: `if` expressions without `else` evaluate to `()`
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= help: consider adding an `else` block that evaluates to the expected type
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error[E0308]: mismatched types
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--> $DIR/if-without-else-as-fn-expr.rs:10:20
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LL | let x: usize = if bar % 5 == 0 {
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| ____________________^
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LL | | return 3;
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LL | | };
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| |_____^ expected usize, found ()
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= note: expected type `usize`
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found type `()`
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error[E0317]: if may be missing an else clause
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--> $DIR/if-without-else-as-fn-expr.rs:10:20
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--> $DIR/if-without-else-as-fn-expr.rs:9:20
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LL | let x: usize = if bar % 5 == 0 {
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| _________-__________^
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@ -52,19 +29,8 @@ LL | | };
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= note: `if` expressions without `else` evaluate to `()`
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= help: consider adding an `else` block that evaluates to the expected type
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error[E0308]: mismatched types
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--> $DIR/if-without-else-as-fn-expr.rs:19:5
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LL | / if bar % 5 == 0 {
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LL | | 3
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LL | | }
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| |_____^ expected usize, found ()
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= note: expected type `usize`
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found type `()`
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error[E0317]: if may be missing an else clause
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--> $DIR/if-without-else-as-fn-expr.rs:19:5
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--> $DIR/if-without-else-as-fn-expr.rs:17:5
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LL | fn foo3(bar: usize) -> usize {
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| ----- expected `usize` because of this return type
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@ -78,19 +44,8 @@ LL | | }
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= note: `if` expressions without `else` evaluate to `()`
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= help: consider adding an `else` block that evaluates to the expected type
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error[E0308]: mismatched types
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--> $DIR/if-without-else-as-fn-expr.rs:27:5
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LL | / if let 0 = 1 {
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LL | | return 3;
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LL | | }
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| |_____^ expected usize, found ()
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= note: expected type `usize`
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found type `()`
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error[E0317]: if may be missing an else clause
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--> $DIR/if-without-else-as-fn-expr.rs:27:5
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--> $DIR/if-without-else-as-fn-expr.rs:24:5
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LL | fn foo_let(bar: usize) -> usize {
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| ----- expected `usize` because of this return type
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@ -104,20 +59,8 @@ LL | | }
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= note: `if` expressions without `else` evaluate to `()`
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= help: consider adding an `else` block that evaluates to the expected type
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error[E0308]: mismatched types
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--> $DIR/if-without-else-as-fn-expr.rs:35:20
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LL | let x: usize = if let 0 = 1 {
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| ____________________^
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LL | | return 3;
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LL | | };
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| |_____^ expected usize, found ()
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= note: expected type `usize`
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found type `()`
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error[E0317]: if may be missing an else clause
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--> $DIR/if-without-else-as-fn-expr.rs:35:20
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--> $DIR/if-without-else-as-fn-expr.rs:31:20
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LL | let x: usize = if let 0 = 1 {
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| _________-__________^
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@ -132,19 +75,8 @@ LL | | };
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= note: `if` expressions without `else` evaluate to `()`
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= help: consider adding an `else` block that evaluates to the expected type
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error[E0308]: mismatched types
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--> $DIR/if-without-else-as-fn-expr.rs:44:5
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LL | / if let 0 = 1 {
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LL | | 3
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LL | | }
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| |_____^ expected usize, found ()
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= note: expected type `usize`
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found type `()`
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error[E0317]: if may be missing an else clause
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--> $DIR/if-without-else-as-fn-expr.rs:44:5
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--> $DIR/if-without-else-as-fn-expr.rs:39:5
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LL | fn foo3_let(bar: usize) -> usize {
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| ----- expected `usize` because of this return type
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@ -158,7 +90,6 @@ LL | | }
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= note: `if` expressions without `else` evaluate to `()`
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= help: consider adding an `else` block that evaluates to the expected type
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error: aborting due to 12 previous errors
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error: aborting due to 6 previous errors
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Some errors have detailed explanations: E0308, E0317.
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For more information about an error, try `rustc --explain E0308`.
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For more information about this error, try `rustc --explain E0317`.
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@ -2,6 +2,5 @@ fn main() {
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enum Foo {
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Drop = assert_eq!(1, 1)
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//~^ ERROR if may be missing an else clause
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//~| ERROR mismatched types [E0308]
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}
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}
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@ -1,13 +1,3 @@
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error[E0308]: mismatched types
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--> $DIR/issue-50577.rs:3:16
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LL | Drop = assert_eq!(1, 1)
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| ^^^^^^^^^^^^^^^^ expected isize, found ()
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= note: expected type `isize`
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found type `()`
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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error[E0317]: if may be missing an else clause
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--> $DIR/issue-50577.rs:3:16
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@ -23,7 +13,6 @@ LL | Drop = assert_eq!(1, 1)
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= help: consider adding an `else` block that evaluates to the expected type
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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error: aborting due to 2 previous errors
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error: aborting due to previous error
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Some errors have detailed explanations: E0308, E0317.
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For more information about an error, try `rustc --explain E0308`.
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For more information about this error, try `rustc --explain E0317`.
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