autofree: handle args in optional returns

vlib/v/ast/ast.v

@@ -287,7 +287,7 @@ pub mut:
 	return_type        table.Type
 	should_be_skipped  bool
 	generic_type       table.Type // TODO array, to support multiple types
-	autofree_pregen    string
+	// autofree_pregen    string
 	// autofree_vars      []AutofreeArgVar
 	// autofree_vars_ids  []int
 }
@@ -593,20 +593,20 @@ pub:
 
 pub struct ForInStmt {
 pub:
-	key_var   string
-	val_var   string
-	cond      Expr
-	is_range  bool
-	high      Expr // `10` in `for i in 0..10 {`
-	stmts     []Stmt
-	pos       token.Position
+	key_var    string
+	val_var    string
+	cond       Expr
+	is_range   bool
+	high       Expr // `10` in `for i in 0..10 {`
+	stmts      []Stmt
+	pos        token.Position
 	val_is_mut bool // `for mut val in vals {` means that modifying `val` will modify the array
-	// and the array cannot be indexed inside the loop
 pub mut:
-	key_type  table.Type
-	val_type  table.Type
-	cond_type table.Type
-	kind      table.Kind // array/map/string
+	// and the array cannot be indexed inside the loop
+	key_type   table.Type
+	val_type   table.Type
+	cond_type  table.Type
+	kind       table.Kind // array/map/string
 }
 
 pub struct ForCStmt {
@@ -989,11 +989,7 @@ pub fn (expr Expr) position() token.Position {
 		AnonFn {
 			return expr.decl.pos
 		}
-		ArrayInit, AsCast, Assoc, BoolLiteral, CallExpr, CastExpr, CharLiteral,
-		Comment, EnumVal, FloatLiteral, Ident, IfExpr, IndexExpr,
-		IntegerLiteral, MapInit, MatchExpr, None, PostfixExpr, PrefixExpr,
-		SelectExpr, SelectorExpr, SizeOf, StringLiteral, StringInterLiteral,
-		StructInit, Likely {
+		ArrayInit, AsCast, Assoc, BoolLiteral, CallExpr, CastExpr, CharLiteral, Comment, EnumVal, FloatLiteral, Ident, IfExpr, IndexExpr, IntegerLiteral, MapInit, MatchExpr, None, PostfixExpr, PrefixExpr, SelectExpr, SelectorExpr, SizeOf, StringLiteral, StringInterLiteral, StructInit, Likely {
 			return expr.pos
 		}
 		InfixExpr {
@@ -1042,11 +1038,15 @@ pub fn (expr Expr) is_expr() bool {
 }
 
 // check if stmt can be an expression in C
-pub fn (stmt Stmt) check_c_expr()? {
+pub fn (stmt Stmt) check_c_expr() ? {
 	match stmt {
-		AssignStmt {return}
+		AssignStmt {
+			return
+		}
 		ExprStmt {
-			if stmt.expr.is_expr() {return}
+			if stmt.expr.is_expr() {
+				return
+			}
 			return error('unsupported statement (`${typeof(stmt.expr)}`)')
 		}
 		else {}
@@ -1056,10 +1056,7 @@ pub fn (stmt Stmt) check_c_expr()? {
 
 pub fn (stmt Stmt) position() token.Position {
 	match stmt {
-		AssertStmt, AssignStmt, Block, ConstDecl, EnumDecl, ExprStmt, FnDecl,
-		ForCStmt, ForInStmt, ForStmt, Import, Return, StructDecl {
-			return stmt.pos
-		}
+		AssertStmt, AssignStmt, Block, ConstDecl, EnumDecl, ExprStmt, FnDecl, ForCStmt, ForInStmt, ForStmt, Import, Return, StructDecl { return stmt.pos }
 		/*
 		Attr {}
 		BranchStmt {}

vlib/v/gen/cgen.v

@@ -985,12 +985,16 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 		}
 		ast.Return {
 			g.write_defer_stmts_when_needed()
+			af := g.pref.autofree && node.exprs.len > 0 && node.exprs[0] is ast.CallExpr && !g.is_builtin_mod
 			if g.pref.autofree {
 				g.writeln('// ast.Return free')
+				if af {
+					g.autofree_call_pregen(node.exprs[0] as ast.CallExpr)
+				}
 				// g.autofree_scope_vars(node.pos.pos)
 				g.write_autofree_stmts_when_needed(node)
 			}
-			g.return_statement(node)
+			g.return_statement(node, af)
 		}
 		ast.SqlStmt {
 			g.sql_stmt(node)
@@ -3458,7 +3462,7 @@ fn (g &Gen) expr_is_multi_return_call(expr ast.Expr) bool {
 	}
 }
 
-fn (mut g Gen) return_statement(node ast.Return) {
+fn (mut g Gen) return_statement(node ast.Return, af bool) {
 	g.write_v_source_line_info(node.pos)
 	if node.exprs.len > 0 {
 		// skip `retun $vweb.html()`
@@ -3496,6 +3500,10 @@ fn (mut g Gen) return_statement(node ast.Return) {
 			g.write('Option $tmp = ')
 			g.expr_with_cast(node.exprs[0], node.types[0], g.fn_decl.return_type)
 			g.writeln(';')
+			if af {
+				// free the tmp arg expr if we have one before the return
+				g.autofree_call_postgen()
+			}
 			styp := g.typ(g.fn_decl.return_type)
 			g.writeln('return *($styp*)&$tmp;')
 			return

vlib/v/tests/valgrind/1.strings_and_arrays.v

@@ -109,6 +109,20 @@ fn optional_str() {
 	println(pos + 1)
 }
 
+fn return_error_with_freed_expr() ?string {
+	if true {
+		msg := 'oops'
+		return error('hm $msg')
+	}
+	return 'ok'
+}
+
+fn optional_return() {
+	return_error_with_freed_expr() or {
+		return
+	}
+}
+
 fn tt() {
 	// time.parse_rfc2822('1234')
 }
@@ -123,6 +137,7 @@ fn main() {
 	match_expr()
 	reassign_str()
 	optional_str()
+	optional_return()
 	// str_replace()
 	println('end')
 }