cgen: fix return if true { 0 } else { none } (fix #9005) (#9030)

vlib/v/checker/checker.v

@@ -4913,9 +4913,14 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) table.Type {
 			if branch.stmts.len > 0 && branch.stmts[branch.stmts.len - 1] is ast.ExprStmt {
 				mut last_expr := branch.stmts[branch.stmts.len - 1] as ast.ExprStmt
 				c.expected_type = former_expected_type
+				if c.expected_type.has_flag(.optional) {
+					if node.typ == table.void_type {
+						node.is_expr = true
+						node.typ = c.expected_type
+					}
+					continue
+				}
 				last_expr.typ = c.expr(last_expr.expr)
-				// if last_expr.typ != node.typ {
-				// if !c.check_types(node.typ, last_expr.typ) {
 				if !c.check_types(last_expr.typ, node.typ) {
 					if node.typ == table.void_type {
 						// first branch of if expression

vlib/v/gen/c/cgen.v

@@ -83,7 +83,7 @@ mut:
 	inside_map_infix      bool     // inside map<</+=/-= infix expr
 	inside_map_index      bool
 	inside_opt_data       bool
-	// inside_if_expr        bool
+	inside_if_optional    bool
 	ternary_names         map[string]string
 	ternary_level_names   map[string][]string
 	stmt_path_pos         []int // positions of each statement start, for inserting C statements before the current statement
@@ -913,11 +913,40 @@ 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.
+			if g.inside_if_optional {
+				g.stmt_path_pos << g.out.len
+				g.skip_stmt_pos = true
+				if stmt is ast.ExprStmt {
+					sym := g.table.get_type_symbol(stmt.typ)
+					if sym.name in ['Option', 'Option2'] || stmt.expr is ast.None {
+						tmp := g.new_tmp_var()
+						g.write('Option2 $tmp = ')
+						g.expr(stmt.expr)
+						g.writeln(';')
+						g.writeln('memcpy(&$tmp_var, &$tmp, sizeof(Option2));')
+					} else {
+						mut styp := g.base_type(stmt.typ)
+						$if tinyc && x32 && windows {
+							if stmt.typ == table.int_literal_type {
+								styp = 'int'
+							} else if stmt.typ == table.float_literal_type {
+								styp = 'f64'
+							}
+						}
+						g.write('opt_ok(&($styp[]) { ')
+						g.stmt(stmt)
+						g.writeln(' }, (Option2*)(&$tmp_var), sizeof($styp));')
+					}
+				}
+			} else {
 				g.stmt_path_pos << g.out.len
 				g.skip_stmt_pos = true
 				g.write('$tmp_var = ')
-		}
 				g.stmt(stmt)
+			}
+		} else {
+			g.stmt(stmt)
+		}
 		g.skip_stmt_pos = false
 		if g.inside_ternary > 0 && i < stmts.len - 1 {
 			g.write(',')
@@ -1076,7 +1105,8 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 			// if af {
 			// g.autofree_call_postgen()
 			// }
-			if g.inside_ternary == 0 && !node.is_expr && node.expr !is ast.IfExpr {
+			if g.inside_ternary == 0 && !g.inside_if_optional && !node.is_expr
+				&& node.expr !is ast.IfExpr {
 				g.writeln(';')
 			}
 		}
@@ -4039,7 +4069,7 @@ fn (mut g Gen) concat_expr(node ast.ConcatExpr) {
 
 fn (mut g Gen) need_tmp_var_in_if(node ast.IfExpr) bool {
 	if node.is_expr && g.inside_ternary == 0 {
-		if g.is_autofree {
+		if g.is_autofree || node.typ.has_flag(.optional) {
 			return true
 		}
 		for branch in node.branches {
@@ -4076,6 +4106,9 @@ fn (mut g Gen) if_expr(node ast.IfExpr) {
 	tmp := if needs_tmp_var { g.new_tmp_var() } else { '' }
 	mut cur_line := ''
 	if needs_tmp_var {
+		if node.typ.has_flag(.optional) {
+			g.inside_if_optional = true
+		}
 		g.write('/*experimental if expr*/')
 		styp := g.typ(node.typ)
 		// g.insert_before_stmt('$styp $tmp;')
@@ -4181,6 +4214,9 @@ fn (mut g Gen) if_expr(node ast.IfExpr) {
 		// g.writeln('$cur_line $tmp; /*Z*/')
 		g.write('$cur_line $tmp /*Z*/')
 	}
+	if node.typ.has_flag(.optional) {
+		g.inside_if_optional = false
+	}
 }
 
 fn (mut g Gen) index_expr(node ast.IndexExpr) {

vlib/v/tests/if_expr_of_optional_test.v

@@ -0,0 +1,25 @@
+fn foo1() ?int {
+    return if true { 0 } else { none }
+}
+
+fn foo2() ?int {
+    return if true { 1 } else { error('foo2 error') }
+}
+
+fn foo3() ?int {
+	return if true { 2 } else { 0 }
+}
+
+fn test_if_expr_of_optional() {
+	a1 := foo1() or { panic('error') }
+	println(a1)
+	assert a1 == 0
+
+	a2 := foo2() or { panic('error') }
+	println(a2)
+	assert a2 == 1
+
+	a3 := foo3() or { panic('error') }
+	println(a3)
+	assert a3 == 2
+}