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address review comments

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This commit is contained in:
Esteban Küber 2019-03-07 14:08:20 -08:00
parent 369058eacd
commit ffa40cb45c
5 changed files with 44 additions and 34 deletions
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58
src/librustc_typeck/check/mod.rs
View File

@ -3474,37 +3474,16 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
} else {
// If this `if` expr is the parent's function return expr, the cause of the type
// coercion is the return type, point at it. (#25228)
let mut ret_reason = None;
if let Node::Block(block) = self.tcx.hir().get_by_hir_id(
self.tcx.hir().get_parent_node_by_hir_id(
self.tcx.hir().get_parent_node_by_hir_id(then_expr.hir_id),
),
) {
// check that the body's parent is an fn
let parent = self.tcx.hir().get_by_hir_id(
self.tcx.hir().get_parent_node_by_hir_id(
self.tcx.hir().get_parent_node_by_hir_id(block.hir_id),
),
);
if let (Some(expr), Node::Item(hir::Item {
node: hir::ItemKind::Fn(..), ..
})) = (&block.expr, parent) {
// check that the `if` expr without `else` is the fn body's expr
if expr.span == sp {
ret_reason = self.get_fn_decl(then_expr.hir_id).map(|(fn_decl, _)| (
fn_decl.output.span(),
format!("found `{}` because of this return type", fn_decl.output),
));
}
}
}
let ret_reason = self.maybe_get_coercion_reason(then_expr.hir_id, sp);
let else_cause = self.cause(sp, ObligationCauseCode::IfExpressionWithNoElse);
coerce.coerce_forced_unit(self, &else_cause, &mut |err| {
if let Some((sp, msg)) = &ret_reason {
err.span_label(*sp, msg.as_str());
}
err.note("`if` expressions without `else` must evaluate to `()`");
}, true);
err.note("`if` expressions without `else` evaluate to `()`");
err.help("consider adding an `else` block that evaluates to the expected type");
}, ret_reason.is_none());
// If the condition is false we can't diverge.
self.diverges.set(cond_diverges);
@ -3518,6 +3497,33 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
}
}
fn maybe_get_coercion_reason(&self, hir_id: hir::HirId, sp: Span) -> Option<(Span, String)> {
if let Node::Block(block) = self.tcx.hir().get_by_hir_id(
self.tcx.hir().get_parent_node_by_hir_id(
self.tcx.hir().get_parent_node_by_hir_id(hir_id),
),
) {
// check that the body's parent is an fn
let parent = self.tcx.hir().get_by_hir_id(
self.tcx.hir().get_parent_node_by_hir_id(
self.tcx.hir().get_parent_node_by_hir_id(block.hir_id),
),
);
if let (Some(expr), Node::Item(hir::Item {
node: hir::ItemKind::Fn(..), ..
})) = (&block.expr, parent) {
// check that the `if` expr without `else` is the fn body's expr
if expr.span == sp {
return self.get_fn_decl(hir_id).map(|(fn_decl, _)| (
fn_decl.output.span(),
format!("expected `{}` because of this return type", fn_decl.output),
));
}
}
}
None
}
// Check field access expressions
fn check_field(&self,
expr: &'gcx hir::Expr,

11
src/test/ui/if/if-without-else-as-fn-expr.stderr
View File

@ -2,15 +2,16 @@ error[E0317]: if may be missing an else clause
--> $DIR/if-without-else-as-fn-expr.rs:2:5
|
LL | fn foo(bar: usize) -> usize {
| ----- found `usize` because of this return type
| ----- expected `usize` because of this return type
LL | / if bar % 5 == 0 {
LL | | return 3;
LL | | }
| |_____^ expected (), found usize
| |_____^ expected usize, found ()
|
= note: expected type `()`
found type `usize`
= note: `if` expressions without `else` must evaluate to `()`
= note: expected type `usize`
found type `()`
= note: `if` expressions without `else` evaluate to `()`
= help: consider adding an `else` block that evaluates to the expected type
error: aborting due to previous error

3
src/test/ui/if/if-without-else-result.stderr
View File

@ -6,7 +6,8 @@ LL | let a = if true { true };
|
= note: expected type `()`
found type `bool`
= note: `if` expressions without `else` must evaluate to `()`
= note: `if` expressions without `else` evaluate to `()`
= help: consider adding an `else` block that evaluates to the expected type
error: aborting due to previous error

3
src/test/ui/issues/issue-4201.stderr
View File

@ -13,7 +13,8 @@ LL | | };
|
= note: expected type `()`
found type `{integer}`
= note: `if` expressions without `else` must evaluate to `()`
= note: `if` expressions without `else` evaluate to `()`
= help: consider adding an `else` block that evaluates to the expected type
error: aborting due to previous error

3
src/test/ui/issues/issue-50577.stderr
View File

@ -6,7 +6,8 @@ LL | Drop = assert_eq!(1, 1)
|
= note: expected type `()`
found type `isize`
= note: `if` expressions without `else` must evaluate to `()`
= note: `if` expressions without `else` evaluate to `()`
= help: consider adding an `else` block that evaluates to the expected type
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
error: aborting due to previous error