Merge #4667

4667: Infer labelled breaks correctly r=flodiebold a=robojumper

Fixes #4663.

Co-authored-by: robojumper <[email protected]>

3 files changed, 94 insertions, 16 deletions

diff --git a/crates/ra_hir_ty/src/infer.rs b/crates/ra_hir_ty/src/infer.rs
index 957d6e0b5..dc77e88e5 100644
--- a/crates/ra_hir_ty/src/infer.rs
+++ b/crates/ra_hir_ty/src/infer.rs
@@ -219,6 +219,17 @@ struct InferenceContext<'a> {
 struct BreakableContext {
     pub may_break: bool,
     pub break_ty: Ty,
+    pub label: Option<name::Name>,
+}
+
+fn find_breakable<'c>(
+    ctxs: &'c mut [BreakableContext],
+    label: Option<&name::Name>,
+) -> Option<&'c mut BreakableContext> {
+    match label {
+        Some(_) => ctxs.iter_mut().rev().find(|ctx| ctx.label.as_ref() == label),
+        None => ctxs.last_mut(),
+    }
 }
 
 impl<'a> InferenceContext<'a> {
diff --git a/crates/ra_hir_ty/src/infer/expr.rs b/crates/ra_hir_ty/src/infer/expr.rs
index 78084cb57..4a98e2deb 100644
--- a/crates/ra_hir_ty/src/infer/expr.rs
+++ b/crates/ra_hir_ty/src/infer/expr.rs
@@ -22,8 +22,8 @@ use crate::{
 };
 
 use super::{
-    BindingMode, BreakableContext, Diverges, Expectation, InferenceContext, InferenceDiagnostic,
-    TypeMismatch,
+    find_breakable, BindingMode, BreakableContext, Diverges, Expectation, InferenceContext,
+    InferenceDiagnostic, TypeMismatch,
 };
 
 impl<'a> InferenceContext<'a> {
@@ -86,16 +86,20 @@ impl<'a> InferenceContext<'a> {
 
                 self.coerce_merge_branch(&then_ty, &else_ty)
             }
-            Expr::Block { statements, tail } => self.infer_block(statements, *tail, expected),
+            Expr::Block { statements, tail, .. } => {
+                // FIXME: Breakable block inference
+                self.infer_block(statements, *tail, expected)
+            }
             Expr::TryBlock { body } => {
                 let _inner = self.infer_expr(*body, expected);
                 // FIXME should be std::result::Result<{inner}, _>
                 Ty::Unknown
             }
-            Expr::Loop { body } => {
+            Expr::Loop { body, label } => {
                 self.breakables.push(BreakableContext {
                     may_break: false,
                     break_ty: self.table.new_type_var(),
+                    label: label.clone(),
                 });
                 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
 
@@ -110,8 +114,12 @@ impl<'a> InferenceContext<'a> {
                     Ty::simple(TypeCtor::Never)
                 }
             }
-            Expr::While { condition, body } => {
-                self.breakables.push(BreakableContext { may_break: false, break_ty: Ty::Unknown });
+            Expr::While { condition, body, label } => {
+                self.breakables.push(BreakableContext {
+                    may_break: false,
+                    break_ty: Ty::Unknown,
+                    label: label.clone(),
+                });
                 // while let is desugared to a match loop, so this is always simple while
                 self.infer_expr(*condition, &Expectation::has_type(Ty::simple(TypeCtor::Bool)));
                 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
@@ -120,10 +128,14 @@ impl<'a> InferenceContext<'a> {
                 self.diverges = Diverges::Maybe;
                 Ty::unit()
             }
-            Expr::For { iterable, body, pat } => {
+            Expr::For { iterable, body, pat, label } => {
                 let iterable_ty = self.infer_expr(*iterable, &Expectation::none());
 
-                self.breakables.push(BreakableContext { may_break: false, break_ty: Ty::Unknown });
+                self.breakables.push(BreakableContext {
+                    may_break: false,
+                    break_ty: Ty::Unknown,
+                    label: label.clone(),
+                });
                 let pat_ty =
                     self.resolve_associated_type(iterable_ty, self.resolve_into_iter_item());
 
@@ -236,23 +248,24 @@ impl<'a> InferenceContext<'a> {
                 let resolver = resolver_for_expr(self.db.upcast(), self.owner, tgt_expr);
                 self.infer_path(&resolver, p, tgt_expr.into()).unwrap_or(Ty::Unknown)
             }
-            Expr::Continue => Ty::simple(TypeCtor::Never),
-            Expr::Break { expr } => {
+            Expr::Continue { .. } => Ty::simple(TypeCtor::Never),
+            Expr::Break { expr, label } => {
                 let val_ty = if let Some(expr) = expr {
                     self.infer_expr(*expr, &Expectation::none())
                 } else {
                     Ty::unit()
                 };
 
-                let last_ty = if let Some(ctxt) = self.breakables.last() {
-                    ctxt.break_ty.clone()
-                } else {
-                    Ty::Unknown
-                };
+                let last_ty =
+                    if let Some(ctxt) = find_breakable(&mut self.breakables, label.as_ref()) {
+                        ctxt.break_ty.clone()
+                    } else {
+                        Ty::Unknown
+                    };
 
                 let merged_type = self.coerce_merge_branch(&last_ty, &val_ty);
 
-                if let Some(ctxt) = self.breakables.last_mut() {
+                if let Some(ctxt) = find_breakable(&mut self.breakables, label.as_ref()) {
                     ctxt.break_ty = merged_type;
                     ctxt.may_break = true;
                 } else {
diff --git a/crates/ra_hir_ty/src/tests/simple.rs b/crates/ra_hir_ty/src/tests/simple.rs
index 839491b9e..88309157b 100644
--- a/crates/ra_hir_ty/src/tests/simple.rs
+++ b/crates/ra_hir_ty/src/tests/simple.rs
@@ -1943,3 +1943,57 @@ fn test() {
     "###
     );
 }
+
+#[test]
+fn infer_labelled_break_with_val() {
+    assert_snapshot!(
+        infer(r#"
+fn foo() {
+    let _x = || 'outer: loop {
+        let inner = 'inner: loop {
+            let i = Default::default();
+            if (break 'outer i) {
+                loop { break 'inner 5i8; };
+            } else if true {
+                break 'inner 6;
+            }
+            break 7;
+        };
+        break inner < 8;
+    };
+}
+"#),
+        @r###"
+    10..336 '{     ...  }; }': ()
+    20..22 '_x': || -> bool
+    25..333 '|| 'ou...     }': || -> bool
+    28..333 ''outer...     }': bool
+    41..333 '{     ...     }': ()
+    55..60 'inner': i8
+    63..301 ''inner...     }': i8
+    76..301 '{     ...     }': ()
+    94..95 'i': bool
+    98..114 'Defaul...efault': {unknown}
+    98..116 'Defaul...ault()': bool
+    130..270 'if (br...     }': ()
+    134..148 'break 'outer i': !
+    147..148 'i': bool
+    150..209 '{     ...     }': ()
+    168..194 'loop {...5i8; }': !
+    173..194 '{ brea...5i8; }': ()
+    175..191 'break ...er 5i8': !
+    188..191 '5i8': i8
+    215..270 'if tru...     }': ()
+    218..222 'true': bool
+    223..270 '{     ...     }': ()
+    241..255 'break 'inner 6': !
+    254..255 '6': i8
+    283..290 'break 7': !
+    289..290 '7': i8
+    311..326 'break inner < 8': !
+    317..322 'inner': i8
+    317..326 'inner < 8': bool
+    325..326 '8': i8
+    "###
+    );
+}