Add break value completion support

```rust
fn foo() -> i32 {
    loop {
        $0
    }
}
```

**Before this PR**:

```rust
fn foo() -> i32 {
    loop {
        break;
    }
}
```

**After this PR**:

```rust
fn foo() -> i32 {
    loop {
        break $0;
    }
}
```

Author: A4-Tacks

src/tools/rust-analyzer/crates/ide-completion/src/completions/expr.rs

@@ -9,7 +9,7 @@ use syntax::ast;
 use crate::{
     CompletionContext, Completions,
     completions::record::add_default_update,
-    context::{BreakableKind, PathCompletionCtx, PathExprCtx, Qualified},
+    context::{PathCompletionCtx, PathExprCtx, Qualified},
 };
 
 struct PathCallback<'a, F> {
@@ -57,7 +57,6 @@ pub(crate) fn complete_expr_path(
 
     let &PathExprCtx {
         in_block_expr,
-        in_breakable,
         after_if_expr,
         before_else_kw,
         in_condition,
@@ -68,6 +67,7 @@ pub(crate) fn complete_expr_path(
         after_amp,
         ref is_func_update,
         ref innermost_ret_ty,
+        ref innermost_breakable_ty,
         ref impl_,
         in_match_guard,
         ..
@@ -405,14 +405,21 @@ pub(crate) fn complete_expr_path(
                         add_keyword("mut", "mut ");
                     }
 
-                    if in_breakable != BreakableKind::None {
+                    if let Some(loop_ty) = innermost_breakable_ty {
                         if in_block_expr {
                             add_keyword("continue", "continue;");
-                            add_keyword("break", "break;");
                         } else {
                             add_keyword("continue", "continue");
-                            add_keyword("break", "break");
                         }
+                        add_keyword(
+                            "break",
+                            match (loop_ty.is_unit(), in_block_expr) {
+                                (true, true) => "break;",
+                                (true, false) => "break",
+                                (false, true) => "break $0;",
+                                (false, false) => "break $0",
+                            },
+                        );
                     }
 
                     if let Some(ret_ty) = innermost_ret_ty {

src/tools/rust-analyzer/crates/ide-completion/src/completions/postfix.rs

@@ -291,7 +291,7 @@ pub(crate) fn complete_postfix(
     )
     .add_to(acc, ctx.db);
 
-    if let BreakableKind::Block | BreakableKind::Loop = expr_ctx.in_breakable {
+    if let Some(BreakableKind::Block | BreakableKind::Loop) = expr_ctx.in_breakable {
         postfix_snippet(
             "break",
             "break expr",

src/tools/rust-analyzer/crates/ide-completion/src/completions/record.rs

@@ -135,10 +135,7 @@ fn complete_fields(
                 receiver: None,
                 receiver_ty: None,
                 kind: DotAccessKind::Field { receiver_is_ambiguous_float_literal: false },
-                ctx: DotAccessExprCtx {
-                    in_block_expr: false,
-                    in_breakable: crate::context::BreakableKind::None,
-                },
+                ctx: DotAccessExprCtx { in_block_expr: false, in_breakable: None },
             },
             None,
             field,

src/tools/rust-analyzer/crates/ide-completion/src/context.rs

@@ -143,7 +143,7 @@ pub(crate) struct AttrCtx {
 #[derive(Debug, PartialEq, Eq)]
 pub(crate) struct PathExprCtx<'db> {
     pub(crate) in_block_expr: bool,
-    pub(crate) in_breakable: BreakableKind,
+    pub(crate) in_breakable: Option<BreakableKind>,
     pub(crate) after_if_expr: bool,
     pub(crate) before_else_kw: bool,
     /// Whether this expression is the direct condition of an if or while expression
@@ -157,6 +157,7 @@ pub(crate) struct PathExprCtx<'db> {
     pub(crate) is_func_update: Option<ast::RecordExpr>,
     pub(crate) self_param: Option<hir::SelfParam>,
     pub(crate) innermost_ret_ty: Option<hir::Type<'db>>,
+    pub(crate) innermost_breakable_ty: Option<hir::Type<'db>>,
     pub(crate) impl_: Option<ast::Impl>,
     /// Whether this expression occurs in match arm guard position: before the
     /// fat arrow token
@@ -412,12 +413,11 @@ pub(crate) enum DotAccessKind {
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub(crate) struct DotAccessExprCtx {
     pub(crate) in_block_expr: bool,
-    pub(crate) in_breakable: BreakableKind,
+    pub(crate) in_breakable: Option<BreakableKind>,
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub(crate) enum BreakableKind {
-    None,
     Loop,
     For,
     While,

src/tools/rust-analyzer/crates/ide-completion/src/context/analysis.rs

@@ -926,7 +926,7 @@ fn classify_name_ref<'db>(
                     receiver_ty,
                     kind: DotAccessKind::Field { receiver_is_ambiguous_float_literal },
                     receiver,
-                    ctx: DotAccessExprCtx { in_block_expr: is_in_block(field.syntax()), in_breakable: is_in_breakable(field.syntax()) }
+                    ctx: DotAccessExprCtx { in_block_expr: is_in_block(field.syntax()), in_breakable: is_in_breakable(field.syntax()).unzip().0 }
                 });
                 return Some(make_res(kind));
             },
@@ -941,7 +941,7 @@ fn classify_name_ref<'db>(
                     receiver_ty: receiver.as_ref().and_then(|it| sema.type_of_expr(it)),
                     kind: DotAccessKind::Method { has_parens },
                     receiver,
-                    ctx: DotAccessExprCtx { in_block_expr: is_in_block(method.syntax()), in_breakable: is_in_breakable(method.syntax()) }
+                    ctx: DotAccessExprCtx { in_block_expr: is_in_block(method.syntax()), in_breakable: is_in_breakable(method.syntax()).unzip().0 }
                 });
                 return Some(make_res(kind));
             },
@@ -1229,7 +1229,7 @@ fn classify_name_ref<'db>(
     let make_path_kind_expr = |expr: ast::Expr| {
         let it = expr.syntax();
         let in_block_expr = is_in_block(it);
-        let in_loop_body = is_in_breakable(it);
+        let (in_loop_body, innermost_breakable) = is_in_breakable(it).unzip();
         let after_if_expr = after_if_expr(it.clone());
         let ref_expr_parent =
             path.as_single_name_ref().and_then(|_| it.parent()).and_then(ast::RefExpr::cast);
@@ -1283,6 +1283,11 @@ fn classify_name_ref<'db>(
                 None => (None, None),
             }
         };
+        let innermost_breakable_ty = innermost_breakable
+            .and_then(ast::Expr::cast)
+            .and_then(|expr| find_node_in_file_compensated(sema, original_file, &expr))
+            .and_then(|expr| sema.type_of_expr(&expr))
+            .map(|ty| if ty.original.is_never() { ty.adjusted() } else { ty.original() });
         let is_func_update = func_update_record(it);
         let in_condition = is_in_condition(&expr);
         let after_incomplete_let = after_incomplete_let(it.clone()).is_some();
@@ -1316,6 +1321,7 @@ fn classify_name_ref<'db>(
                 after_amp,
                 is_func_update,
                 innermost_ret_ty,
+                innermost_breakable_ty,
                 self_param,
                 in_value,
                 incomplete_let,
@@ -1865,24 +1871,22 @@ fn is_in_token_of_for_loop(path: &ast::Path) -> bool {
     .unwrap_or(false)
 }
 
-fn is_in_breakable(node: &SyntaxNode) -> BreakableKind {
+fn is_in_breakable(node: &SyntaxNode) -> Option<(BreakableKind, SyntaxNode)> {
     node.ancestors()
         .take_while(|it| it.kind() != SyntaxKind::FN && it.kind() != SyntaxKind::CLOSURE_EXPR)
         .find_map(|it| {
             let (breakable, loop_body) = match_ast! {
                 match it {
-                    ast::ForExpr(it) => (BreakableKind::For, it.loop_body()),
-                    ast::WhileExpr(it) => (BreakableKind::While, it.loop_body()),
-                    ast::LoopExpr(it) => (BreakableKind::Loop, it.loop_body()),
-                    ast::BlockExpr(it) => return it.label().map(|_| BreakableKind::Block),
+                    ast::ForExpr(it) => (BreakableKind::For, it.loop_body()?),
+                    ast::WhileExpr(it) => (BreakableKind::While, it.loop_body()?),
+                    ast::LoopExpr(it) => (BreakableKind::Loop, it.loop_body()?),
+                    ast::BlockExpr(it) => return it.label().map(|_| (BreakableKind::Block, it.syntax().clone())),
                     _ => return None,
                 }
             };
-            loop_body
-                .filter(|it| it.syntax().text_range().contains_range(node.text_range()))
-                .map(|_| breakable)
+            loop_body.syntax().text_range().contains_range(node.text_range())
+                .then_some((breakable, it))
         })
-        .unwrap_or(BreakableKind::None)
 }
 
 fn is_in_block(node: &SyntaxNode) -> bool {

src/tools/rust-analyzer/crates/ide-completion/src/tests/expression.rs

@@ -1090,6 +1090,45 @@ fn return_value_no_block() {
     );
 }
 
+#[test]
+fn break_unit_block() {
+    check_edit("break", r#"fn f() { loop { break; $0 } }"#, r#"fn f() { loop { break; break; } }"#);
+    check_edit("break", r#"fn f() { loop { $0 } }"#, r#"fn f() { loop { break; } }"#);
+}
+
+#[test]
+fn break_unit_no_block() {
+    check_edit(
+        "break",
+        r#"fn f() { loop { break; match () { () => $0 } } }"#,
+        r#"fn f() { loop { break; match () { () => break } } }"#,
+    );
+
+    check_edit(
+        "break",
+        r#"fn f() { loop { match () { () => $0 } } }"#,
+        r#"fn f() { loop { match () { () => break } } }"#,
+    );
+}
+
+#[test]
+fn break_value_block() {
+    check_edit(
+        "break",
+        r#"fn f() -> i32 { loop { $0 } }"#,
+        r#"fn f() -> i32 { loop { break $0; } }"#,
+    );
+}
+
+#[test]
+fn break_value_no_block() {
+    check_edit(
+        "break",
+        r#"fn f() -> i32 { loop { match () { () => $0 } } }"#,
+        r#"fn f() -> i32 { loop { match () { () => break $0 } } }"#,
+    );
+}
+
 #[test]
 fn else_completion_after_if() {
     check(