Auto merge of #18152 - CryZe:highlight-async-block-exit-points, r=Veykril

feat: Highlight exit points of async blocks

Async blocks act similar to async functions in that the await keywords are related, but also act like functions where the exit points are related.

Fixes #18147

Author: bors

src/tools/rust-analyzer/crates/ide/src/highlight_related.rs

@@ -281,99 +281,95 @@ fn highlight_references(
     }
 }
 
-// If `file_id` is None,
-pub(crate) fn highlight_exit_points(
+fn hl_exit_points(
     sema: &Semantics<'_, RootDatabase>,
-    token: SyntaxToken,
-) -> FxHashMap<EditionedFileId, Vec<HighlightedRange>> {
-    fn hl(
-        sema: &Semantics<'_, RootDatabase>,
-        def_token: Option<SyntaxToken>,
-        body: ast::Expr,
-    ) -> Option<FxHashMap<EditionedFileId, FxHashSet<HighlightedRange>>> {
-        let mut highlights: FxHashMap<EditionedFileId, FxHashSet<_>> = FxHashMap::default();
+    def_token: Option<SyntaxToken>,
+    body: ast::Expr,
+) -> Option<FxHashMap<EditionedFileId, FxHashSet<HighlightedRange>>> {
+    let mut highlights: FxHashMap<EditionedFileId, FxHashSet<_>> = FxHashMap::default();
+
+    let mut push_to_highlights = |file_id, range| {
+        if let Some(FileRange { file_id, range }) = original_frange(sema.db, file_id, range) {
+            let hrange = HighlightedRange { category: ReferenceCategory::empty(), range };
+            highlights.entry(file_id).or_default().insert(hrange);
+        }
+    };
 
-        let mut push_to_highlights = |file_id, range| {
-            if let Some(FileRange { file_id, range }) = original_frange(sema.db, file_id, range) {
-                let hrange = HighlightedRange { category: ReferenceCategory::empty(), range };
-                highlights.entry(file_id).or_default().insert(hrange);
+    if let Some(tok) = def_token {
+        let file_id = sema.hir_file_for(&tok.parent()?);
+        let range = Some(tok.text_range());
+        push_to_highlights(file_id, range);
+    }
+
+    WalkExpandedExprCtx::new(sema).walk(&body, &mut |_, expr| {
+        let file_id = sema.hir_file_for(expr.syntax());
+
+        let range = match &expr {
+            ast::Expr::TryExpr(try_) => try_.question_mark_token().map(|token| token.text_range()),
+            ast::Expr::MethodCallExpr(_) | ast::Expr::CallExpr(_) | ast::Expr::MacroExpr(_)
+                if sema.type_of_expr(&expr).map_or(false, |ty| ty.original.is_never()) =>
+            {
+                Some(expr.syntax().text_range())
             }
+            _ => None,
         };
 
-        if let Some(tok) = def_token {
-            let file_id = sema.hir_file_for(&tok.parent()?);
-            let range = Some(tok.text_range());
-            push_to_highlights(file_id, range);
-        }
+        push_to_highlights(file_id, range);
+    });
 
-        WalkExpandedExprCtx::new(sema).walk(&body, &mut |_, expr| {
+    // We should handle `return` separately, because when it is used in a `try` block,
+    // it will exit the outside function instead of the block itself.
+    WalkExpandedExprCtx::new(sema)
+        .with_check_ctx(&WalkExpandedExprCtx::is_async_const_block_or_closure)
+        .walk(&body, &mut |_, expr| {
             let file_id = sema.hir_file_for(expr.syntax());
 
             let range = match &expr {
-                ast::Expr::TryExpr(try_) => {
-                    try_.question_mark_token().map(|token| token.text_range())
-                }
-                ast::Expr::MethodCallExpr(_) | ast::Expr::CallExpr(_) | ast::Expr::MacroExpr(_)
-                    if sema.type_of_expr(&expr).map_or(false, |ty| ty.original.is_never()) =>
-                {
-                    Some(expr.syntax().text_range())
-                }
+                ast::Expr::ReturnExpr(expr) => expr.return_token().map(|token| token.text_range()),
                 _ => None,
             };
 
             push_to_highlights(file_id, range);
         });
 
-        // We should handle `return` separately, because when it is used in a `try` block,
-        // it will exit the outside function instead of the block itself.
-        WalkExpandedExprCtx::new(sema)
-            .with_check_ctx(&WalkExpandedExprCtx::is_async_const_block_or_closure)
-            .walk(&body, &mut |_, expr| {
-                let file_id = sema.hir_file_for(expr.syntax());
-
-                let range = match &expr {
-                    ast::Expr::ReturnExpr(expr) => {
-                        expr.return_token().map(|token| token.text_range())
-                    }
-                    _ => None,
-                };
-
-                push_to_highlights(file_id, range);
-            });
-
-        let tail = match body {
-            ast::Expr::BlockExpr(b) => b.tail_expr(),
-            e => Some(e),
-        };
+    let tail = match body {
+        ast::Expr::BlockExpr(b) => b.tail_expr(),
+        e => Some(e),
+    };
 
-        if let Some(tail) = tail {
-            for_each_tail_expr(&tail, &mut |tail| {
-                let file_id = sema.hir_file_for(tail.syntax());
-                let range = match tail {
-                    ast::Expr::BreakExpr(b) => b
-                        .break_token()
-                        .map_or_else(|| tail.syntax().text_range(), |tok| tok.text_range()),
-                    _ => tail.syntax().text_range(),
-                };
-                push_to_highlights(file_id, Some(range));
-            });
-        }
-        Some(highlights)
+    if let Some(tail) = tail {
+        for_each_tail_expr(&tail, &mut |tail| {
+            let file_id = sema.hir_file_for(tail.syntax());
+            let range = match tail {
+                ast::Expr::BreakExpr(b) => b
+                    .break_token()
+                    .map_or_else(|| tail.syntax().text_range(), |tok| tok.text_range()),
+                _ => tail.syntax().text_range(),
+            };
+            push_to_highlights(file_id, Some(range));
+        });
     }
+    Some(highlights)
+}
 
+// If `file_id` is None,
+pub(crate) fn highlight_exit_points(
+    sema: &Semantics<'_, RootDatabase>,
+    token: SyntaxToken,
+) -> FxHashMap<EditionedFileId, Vec<HighlightedRange>> {
     let mut res = FxHashMap::default();
     for def in goto_definition::find_fn_or_blocks(sema, &token) {
         let new_map = match_ast! {
             match def {
-                ast::Fn(fn_) => fn_.body().and_then(|body| hl(sema, fn_.fn_token(), body.into())),
+                ast::Fn(fn_) => fn_.body().and_then(|body| hl_exit_points(sema, fn_.fn_token(), body.into())),
                 ast::ClosureExpr(closure) => {
                     let pipe_tok = closure.param_list().and_then(|p| p.pipe_token());
-                    closure.body().and_then(|body| hl(sema, pipe_tok, body))
+                    closure.body().and_then(|body| hl_exit_points(sema, pipe_tok, body))
                 },
                 ast::BlockExpr(blk) => match blk.modifier() {
-                    Some(ast::BlockModifier::Async(t)) => hl(sema, Some(t), blk.into()),
+                    Some(ast::BlockModifier::Async(t)) => hl_exit_points(sema, Some(t), blk.into()),
                     Some(ast::BlockModifier::Try(t)) if token.kind() != T![return] => {
-                        hl(sema, Some(t), blk.into())
+                        hl_exit_points(sema, Some(t), blk.into())
                     },
                     _ => continue,
                 },
@@ -517,10 +513,23 @@ pub(crate) fn highlight_yield_points(
             match anc {
                 ast::Fn(fn_) => hl(sema, fn_.async_token(), fn_.body().map(ast::Expr::BlockExpr)),
                 ast::BlockExpr(block_expr) => {
-                    if block_expr.async_token().is_none() {
+                    let Some(async_token) = block_expr.async_token() else {
                         continue;
+                    };
+
+                    // Async blocks act similar to closures. So we want to
+                    // highlight their exit points too, but only if we are on
+                    // the async token.
+                    if async_token == token {
+                        let exit_points = hl_exit_points(
+                            sema,
+                            Some(async_token.clone()),
+                            block_expr.clone().into(),
+                        );
+                        merge_map(&mut res, exit_points);
                     }
-                    hl(sema, block_expr.async_token(), Some(block_expr.into()))
+
+                    hl(sema, Some(async_token), Some(block_expr.into()))
                 },
                 ast::ClosureExpr(closure) => hl(sema, closure.async_token(), closure.body()),
                 _ => continue,
@@ -876,6 +885,27 @@ pub async$0 fn foo() {
         );
     }
 
+    #[test]
+    fn test_hl_exit_points_of_async_blocks() {
+        check(
+            r#"
+pub fn foo() {
+    let x = async$0 {
+         // ^^^^^
+        0.await;
+       // ^^^^^
+       0?;
+     // ^
+       return 0;
+    // ^^^^^^
+       0
+    // ^
+    };
+}
+"#,
+        );
+    }
+
     #[test]
     fn test_hl_let_else_yield_points() {
         check(
@@ -925,11 +955,9 @@ async fn foo() {
 async fn foo() {
     (async {
   // ^^^^^
-        (async {
-           0.await
-        }).await$0 }
-        // ^^^^^
-    ).await;
+        (async { 0.await }).await$0
+                         // ^^^^^
+    }).await;
 }
 "#,
         );