autofree: fix if expressions

vlib/v/gen/cgen.v

@@ -74,7 +74,8 @@ mut:
 	// inside_if_expr        bool
 	ternary_names         map[string]string
 	ternary_level_names   map[string][]string
-	stmt_path_pos         []int
+	stmt_path_pos         []int // positions of each statement start, for inserting C statements before the current statement
+	skip_stmt_pos         bool // for handling if expressions + autofree (since both prepend C statements)
 	right_is_opt          bool
 	autofree              bool
 	indent                int
@@ -725,9 +726,12 @@ fn (mut g Gen) stmts_with_tmp_var(stmts []ast.Stmt, tmp_var string) {
 	for i, stmt in stmts {
 		if i == stmts.len - 1 && tmp_var != '' {
 			// Handle if expressions, set the value of the last expression to the temp var.
+			g.stmt_path_pos << g.out.len
+			g.skip_stmt_pos = true
 			g.writeln('$tmp_var = /* if expr set */')
 		}
 		g.stmt(stmt)
+		g.skip_stmt_pos = false
 		if g.inside_ternary > 0 && i < stmts.len - 1 {
 			g.write(',')
 		}
@@ -761,7 +765,9 @@ fn (mut g Gen) write_v_source_line_info(pos token.Position) {
 }
 
 fn (mut g Gen) stmt(node ast.Stmt) {
+	if !g.skip_stmt_pos {
 		g.stmt_path_pos << g.out.len
+	}
 	defer {
 		// If we have temporary string exprs to free after this statement, do it. e.g.:
 		// `foo('a' + 'b')` => `tmp := 'a' + 'b'; foo(tmp); string_free(&tmp);`
@@ -1047,8 +1053,10 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 			g.writeln('// TypeDecl')
 		}
 	}
+	if !g.skip_stmt_pos { // && g.stmt_path_pos.len > 0 {
 		g.stmt_path_pos.delete_last()
 	}
+}
 
 fn (mut g Gen) write_defer_stmts() {
 	for defer_stmt in g.defer_stmts {

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

@@ -159,10 +159,14 @@ fn tt() {
 }
 
 fn get_string(s string) string {
-	return s
+	return s.clone() // TODO handle returning the argument without clone()
+}
+
+fn if_expr() string {
+	a := if true { get_string('a' + 'b') } else { get_string('c' + 'd') }
+	return a
 }
 
-/*
 fn return_if_expr() string {
 	return if true {
 		get_string('a' + 'b')
@@ -170,7 +174,7 @@ fn return_if_expr() string {
 		get_string('c' + 'd')
 	}
 }
-*/
+
 fn main() {
 	println('start')
 	simple()
@@ -186,7 +190,8 @@ fn main() {
 	str_replace2()
 	if_cond()
 	addition_with_tmp_expr()
-	// return_if_expr()
+	if_expr()
+	return_if_expr()
 	println('end')
 }