parser, checker: only collect/hoist inner vars, when defer is function-scoped (#25693)

Author: StunxFS

vlib/v/checker/checker.v

@@ -2433,24 +2433,24 @@ fn (mut c Checker) defer_stmt(mut node ast.DeferStmt) {
 		if c.locked_names.len != 0 || c.rlocked_names.len != 0 {
 			c.error('`defer(fn)`s are not allowed in lock statements', node.pos)
 		}
-	}
-	for i, ident in node.defer_vars {
-		mut id := ident
-		if mut id.info is ast.IdentVar {
-			if id.comptime
-				&& (id.tok_kind == .question || id.name in ast.valid_comptime_not_user_defined) {
-				node.defer_vars[i] = ast.Ident{
-					scope: unsafe { nil }
-					name:  ''
+		for i, ident in node.defer_vars {
+			mut id := ident
+			if mut id.info is ast.IdentVar {
+				if id.comptime
+					&& (id.tok_kind == .question || id.name in ast.valid_comptime_not_user_defined) {
+					node.defer_vars[i] = ast.Ident{
+						scope: unsafe { nil }
+						name:  ''
+					}
+					continue
 				}
-				continue
-			}
-			typ := c.ident(mut id)
-			if typ == ast.error_type_idx {
-				continue
+				typ := c.ident(mut id)
+				if typ == ast.error_type_idx {
+					continue
+				}
+				id.info.typ = typ
+				node.defer_vars[i] = id
 			}
-			id.info.typ = typ
-			node.defer_vars[i] = id
 		}
 	}
 	c.stmts(mut node.stmts)

vlib/v/parser/assign.v

@@ -7,11 +7,11 @@ import v.ast
 
 fn (mut p Parser) assign_stmt() ast.Stmt {
 	mut defer_vars := p.defer_vars.clone()
-	p.defer_vars = []ast.Ident{}
+	p.defer_vars = []
 
 	exprs := p.expr_list(true)
 
-	if !(p.inside_defer && p.tok.kind == .decl_assign) {
+	if !(p.inside_defer && p.defer_mode == .function && p.tok.kind == .decl_assign) {
 		defer_vars << p.defer_vars
 	}
 	p.defer_vars = defer_vars

vlib/v/parser/parser.v

@@ -63,6 +63,7 @@ mut:
 	inside_asm_template      bool
 	inside_asm               bool
 	inside_defer             bool
+	defer_mode               ast.DeferMode
 	inside_generic_params    bool // indicates if parsing between `<` and `>` of a method/function
 	inside_receiver_param    bool // indicates if parsing the receiver parameter inside the first `(` and `)` of a method
 	inside_struct_field_decl bool
@@ -1147,6 +1148,7 @@ fn (mut p Parser) stmt(is_top_level bool) ast.Stmt {
 					p.check(.rpar)
 				}
 				p.inside_defer = true
+				p.defer_mode = defer_mode
 				p.defer_vars = []ast.Ident{}
 				stmts := p.parse_block()
 				p.inside_defer = false
@@ -1253,10 +1255,9 @@ fn (mut p Parser) parse_multi_expr(is_top_level bool) ast.Stmt {
 
 	left := p.expr_list(p.inside_assign_rhs)
 
-	if !(p.inside_defer && p.tok.kind == .decl_assign) {
+	if !(p.inside_defer && p.defer_mode == .function && p.tok.kind == .decl_assign) {
 		defer_vars << p.defer_vars
 	}
-
 	p.defer_vars = defer_vars
 
 	left0 := left[0]
@@ -3237,7 +3238,7 @@ fn (mut p Parser) show(params ParserShowParams) {
 }
 
 fn (mut p Parser) add_defer_var(ident ast.Ident) {
-	if p.inside_defer {
+	if p.inside_defer && p.defer_mode == .function {
 		if !p.defer_vars.any(it.name == ident.name && it.mod == ident.mod)
 			&& ident.name !in ['err', 'it'] {
 			p.defer_vars << ident

vlib/v/tests/defer/scoped_defer_test.v

@@ -117,3 +117,16 @@ fn test_defer_with_comptime_for() {
 	}
 	assert c == 3
 }
+
+fn test_defer_fn_with_inner_var() {
+	mut x := 0
+	defer {
+		assert x == 1
+	}
+	{
+		a := 1
+		defer(fn) {
+			x = a
+		}
+	}
+}