Fix macro expansion for statements without semicolon

crates/hir_def/src/body/lower.rs

@@ -519,21 +519,33 @@ impl ExprCollector<'_> {
             }
             ast::Expr::MacroCall(e) => {
                 let mut ids = vec![];
-                self.collect_macro_call(e, syntax_ptr.clone(), |this, expansion| {
+                self.collect_macro_call(e, syntax_ptr.clone(), true, |this, expansion| {
                     ids.push(match expansion {
                         Some(it) => this.collect_expr(it),
                         None => this.alloc_expr(Expr::Missing, syntax_ptr.clone()),
                     })
                 });
                 ids[0]
             }
+            ast::Expr::MacroStmts(e) => {
+                // FIXME:  these statements should be held by some hir containter
+                for stmt in e.statements() {
+                    self.collect_stmt(stmt);
+                }
+                if let Some(expr) = e.expr() {
+                    self.collect_expr(expr)
+                } else {
+                    self.alloc_expr(Expr::Missing, syntax_ptr)
+                }
+            }
         }
     }
 
     fn collect_macro_call<F: FnMut(&mut Self, Option<T>), T: ast::AstNode>(
         &mut self,
         e: ast::MacroCall,
         syntax_ptr: AstPtr<ast::Expr>,
+        is_error_recoverable: bool,
         mut collector: F,
     ) {
         // File containing the macro call. Expansion errors will be attached here.
@@ -567,7 +579,7 @@ impl ExprCollector<'_> {
             Some((mark, expansion)) => {
                 // FIXME: Statements are too complicated to recover from error for now.
                 // It is because we don't have any hygiene for local variable expansion right now.
-                if T::can_cast(syntax::SyntaxKind::MACRO_STMTS) && res.err.is_some() {
+                if !is_error_recoverable && res.err.is_some() {
                     self.expander.exit(self.db, mark);
                     collector(self, None);
                 } else {
@@ -591,56 +603,55 @@ impl ExprCollector<'_> {
     }
 
     fn collect_stmt(&mut self, s: ast::Stmt) -> Option<Vec<Statement>> {
-        let stmt =
-            match s {
-                ast::Stmt::LetStmt(stmt) => {
-                    self.check_cfg(&stmt)?;
-
-                    let pat = self.collect_pat_opt(stmt.pat());
-                    let type_ref = stmt.ty().map(|it| TypeRef::from_ast(&self.ctx(), it));
-                    let initializer = stmt.initializer().map(|e| self.collect_expr(e));
-                    vec![Statement::Let { pat, type_ref, initializer }]
-                }
-                ast::Stmt::ExprStmt(stmt) => {
-                    self.check_cfg(&stmt)?;
-
-                    // Note that macro could be expended to multiple statements
-                    if let Some(ast::Expr::MacroCall(m)) = stmt.expr() {
-                        let syntax_ptr = AstPtr::new(&stmt.expr().unwrap());
-                        let mut stmts = vec![];
-
-                        self.collect_macro_call(m, syntax_ptr.clone(), |this, expansion| {
-                            match expansion {
-                                Some(expansion) => {
-                                    let statements: ast::MacroStmts = expansion;
-
-                                    statements.statements().for_each(|stmt| {
-                                        if let Some(mut r) = this.collect_stmt(stmt) {
-                                            stmts.append(&mut r);
-                                        }
-                                    });
-                                    if let Some(expr) = statements.expr() {
-                                        stmts.push(Statement::Expr(this.collect_expr(expr)));
+        let stmt = match s {
+            ast::Stmt::LetStmt(stmt) => {
+                self.check_cfg(&stmt)?;
+
+                let pat = self.collect_pat_opt(stmt.pat());
+                let type_ref = stmt.ty().map(|it| TypeRef::from_ast(&self.ctx(), it));
+                let initializer = stmt.initializer().map(|e| self.collect_expr(e));
+                vec![Statement::Let { pat, type_ref, initializer }]
+            }
+            ast::Stmt::ExprStmt(stmt) => {
+                self.check_cfg(&stmt)?;
+
+                // Note that macro could be expended to multiple statements
+                if let Some(ast::Expr::MacroCall(m)) = stmt.expr() {
+                    let syntax_ptr = AstPtr::new(&stmt.expr().unwrap());
+                    let mut stmts = vec![];
+
+                    self.collect_macro_call(m, syntax_ptr.clone(), false, |this, expansion| {
+                        match expansion {
+                            Some(expansion) => {
+                                let statements: ast::MacroStmts = expansion;
+
+                                statements.statements().for_each(|stmt| {
+                                    if let Some(mut r) = this.collect_stmt(stmt) {
+                                        stmts.append(&mut r);
                                     }
-                                }
-                                None => {
-                                    stmts.push(Statement::Expr(
-                                        this.alloc_expr(Expr::Missing, syntax_ptr.clone()),
-                                    ));
+                                });
+                                if let Some(expr) = statements.expr() {
+                                    stmts.push(Statement::Expr(this.collect_expr(expr)));
                                 }
                             }
-                        });
-                        stmts
-                    } else {
-                        vec![Statement::Expr(self.collect_expr_opt(stmt.expr()))]
-                    }
+                            None => {
+                                stmts.push(Statement::Expr(
+                                    this.alloc_expr(Expr::Missing, syntax_ptr.clone()),
+                                ));
+                            }
+                        }
+                    });
+                    stmts
+                } else {
+                    vec![Statement::Expr(self.collect_expr_opt(stmt.expr()))]
                 }
-                ast::Stmt::Item(item) => {
-                    self.check_cfg(&item)?;
+            }
+            ast::Stmt::Item(item) => {
+                self.check_cfg(&item)?;
 
-                    return None;
-                }
-            };
+                return None;
+            }
+        };
 
         Some(stmt)
     }

crates/hir_def/src/item_tree.rs

@@ -110,6 +110,11 @@ impl ItemTree {
                     // still need to collect inner items.
                     ctx.lower_inner_items(e.syntax())
                 },
+                ast::ExprStmt(stmt) => {
+                    // Macros can expand to stmt. We return an empty item tree in this case, but
+                    // still need to collect inner items.
+                    ctx.lower_inner_items(stmt.syntax())
+                },
                 _ => {
                     panic!("cannot create item tree from {:?} {}", syntax, syntax);
                 },

crates/hir_expand/src/db.rs

@@ -401,13 +401,14 @@ fn to_fragment_kind(db: &dyn AstDatabase, id: MacroCallId) -> FragmentKind {
 
     match parent.kind() {
         MACRO_ITEMS | SOURCE_FILE => FragmentKind::Items,
+        MACRO_STMTS => FragmentKind::Statement,
         ITEM_LIST => FragmentKind::Items,
         LET_STMT => {
             // FIXME: Handle Pattern
             FragmentKind::Expr
         }
         EXPR_STMT => FragmentKind::Statements,
-        BLOCK_EXPR => FragmentKind::Expr,
+        BLOCK_EXPR => FragmentKind::Statements,
         ARG_LIST => FragmentKind::Expr,
         TRY_EXPR => FragmentKind::Expr,
         TUPLE_EXPR => FragmentKind::Expr,

crates/hir_ty/src/tests/macros.rs

@@ -215,6 +215,22 @@ fn expr_macro_expanded_in_various_places() {
     );
 }
 
+#[test]
+fn expr_macro_expanded_in_stmts() {
+    check_infer(
+        r#"
+        macro_rules! id { ($($es:tt)*) => { $($es)* } }
+        fn foo() {
+            id! { let a = (); }
+        }
+        "#,
+        expect![[r#"
+            !0..8 'leta=();': ()
+            57..84 '{     ...); } }': ()
+        "#]],
+    );
+}
+
 #[test]
 fn infer_type_value_macro_having_same_name() {
     check_infer(

crates/mbe/src/tests.rs

@@ -662,12 +662,11 @@ fn test_tt_to_stmts() {
         [email protected]
           [email protected] "1"
     [email protected] ";"
-  [email protected]
-    [email protected]
-      [email protected]
-        [email protected]
-          [email protected]
-            [email protected] "a""#,
+  [email protected]
+    [email protected]
+      [email protected]
+        [email protected]
+          [email protected] "a""#,
     );
 }
 

crates/parser/src/grammar.rs

@@ -63,11 +63,11 @@ pub(crate) mod fragments {
     }
 
     pub(crate) fn stmt(p: &mut Parser) {
-        expressions::stmt(p, expressions::StmtWithSemi::No)
+        expressions::stmt(p, expressions::StmtWithSemi::No, true)
     }
 
     pub(crate) fn stmt_optional_semi(p: &mut Parser) {
-        expressions::stmt(p, expressions::StmtWithSemi::Optional)
+        expressions::stmt(p, expressions::StmtWithSemi::Optional, false)
     }
 
     pub(crate) fn opt_visibility(p: &mut Parser) {
@@ -133,7 +133,7 @@ pub(crate) mod fragments {
                 continue;
             }
 
-            expressions::stmt(p, expressions::StmtWithSemi::Optional);
+            expressions::stmt(p, expressions::StmtWithSemi::Optional, true);
         }
 
         m.complete(p, MACRO_STMTS);

crates/parser/src/grammar/expressions.rs

@@ -54,7 +54,7 @@ fn is_expr_stmt_attr_allowed(kind: SyntaxKind) -> bool {
     !forbid
 }
 
-pub(super) fn stmt(p: &mut Parser, with_semi: StmtWithSemi) {
+pub(super) fn stmt(p: &mut Parser, with_semi: StmtWithSemi, prefer_expr: bool) {
     let m = p.start();
     // test attr_on_expr_stmt
     // fn foo() {
@@ -90,7 +90,7 @@ pub(super) fn stmt(p: &mut Parser, with_semi: StmtWithSemi) {
         p.error(format!("attributes are not allowed on {:?}", kind));
     }
 
-    if p.at(T!['}']) {
+    if p.at(T!['}']) || (prefer_expr && p.at(EOF)) {
         // test attr_on_last_expr_in_block
         // fn foo() {
         //     { #[A] bar!()? }
@@ -198,7 +198,7 @@ pub(super) fn expr_block_contents(p: &mut Parser) {
             continue;
         }
 
-        stmt(p, StmtWithSemi::Yes)
+        stmt(p, StmtWithSemi::Yes, false)
     }
 }
 

crates/syntax/src/ast/generated/nodes.rs

@@ -1336,6 +1336,7 @@ pub enum Expr {
     Literal(Literal),
     LoopExpr(LoopExpr),
     MacroCall(MacroCall),
+    MacroStmts(MacroStmts),
     MatchExpr(MatchExpr),
     MethodCallExpr(MethodCallExpr),
     ParenExpr(ParenExpr),
@@ -3034,6 +3035,9 @@ impl From<LoopExpr> for Expr {
 impl From<MacroCall> for Expr {
     fn from(node: MacroCall) -> Expr { Expr::MacroCall(node) }
 }
+impl From<MacroStmts> for Expr {
+    fn from(node: MacroStmts) -> Expr { Expr::MacroStmts(node) }
+}
 impl From<MatchExpr> for Expr {
     fn from(node: MatchExpr) -> Expr { Expr::MatchExpr(node) }
 }
@@ -3078,8 +3082,8 @@ impl AstNode for Expr {
         match kind {
             ARRAY_EXPR | AWAIT_EXPR | BIN_EXPR | BLOCK_EXPR | BOX_EXPR | BREAK_EXPR | CALL_EXPR
             | CAST_EXPR | CLOSURE_EXPR | CONTINUE_EXPR | EFFECT_EXPR | FIELD_EXPR | FOR_EXPR
-            | IF_EXPR | INDEX_EXPR | LITERAL | LOOP_EXPR | MACRO_CALL | MATCH_EXPR
-            | METHOD_CALL_EXPR | PAREN_EXPR | PATH_EXPR | PREFIX_EXPR | RANGE_EXPR
+            | IF_EXPR | INDEX_EXPR | LITERAL | LOOP_EXPR | MACRO_CALL | MACRO_STMTS
+            | MATCH_EXPR | METHOD_CALL_EXPR | PAREN_EXPR | PATH_EXPR | PREFIX_EXPR | RANGE_EXPR
             | RECORD_EXPR | REF_EXPR | RETURN_EXPR | TRY_EXPR | TUPLE_EXPR | WHILE_EXPR
             | YIELD_EXPR => true,
             _ => false,
@@ -3105,6 +3109,7 @@ impl AstNode for Expr {
             LITERAL => Expr::Literal(Literal { syntax }),
             LOOP_EXPR => Expr::LoopExpr(LoopExpr { syntax }),
             MACRO_CALL => Expr::MacroCall(MacroCall { syntax }),
+            MACRO_STMTS => Expr::MacroStmts(MacroStmts { syntax }),
             MATCH_EXPR => Expr::MatchExpr(MatchExpr { syntax }),
             METHOD_CALL_EXPR => Expr::MethodCallExpr(MethodCallExpr { syntax }),
             PAREN_EXPR => Expr::ParenExpr(ParenExpr { syntax }),
@@ -3142,6 +3147,7 @@ impl AstNode for Expr {
             Expr::Literal(it) => &it.syntax,
             Expr::LoopExpr(it) => &it.syntax,
             Expr::MacroCall(it) => &it.syntax,
+            Expr::MacroStmts(it) => &it.syntax,
             Expr::MatchExpr(it) => &it.syntax,
             Expr::MethodCallExpr(it) => &it.syntax,
             Expr::ParenExpr(it) => &it.syntax,

xtask/Cargo.toml

@@ -11,7 +11,7 @@ anyhow = "1.0.26"
 flate2 = "1.0"
 proc-macro2 = "1.0.8"
 quote = "1.0.2"
-ungrammar = "=1.11"
+ungrammar = "=1.12"
 walkdir = "2.3.1"
 write-json = "0.1.0"
 xshell = "0.1"