checker, cgen: fix match expr with branch returning (#16741)

vlib/v/checker/match.v

@@ -72,7 +72,7 @@ fn (mut c Checker) match_expr(mut node ast.MatchExpr) ast.Type {
 				} else if node.is_expr && ret_type.idx() != expr_type.idx() {
 					c.check_match_branch_last_stmt(stmt, ret_type, expr_type)
 				}
-			} else {
+			} else if stmt !is ast.Return {
 				if node.is_expr && ret_type != ast.void_type {
 					c.error('`match` expression requires an expression as the last statement of every branch',
 						stmt.pos)

vlib/v/checker/tests/match_expr_non_void_stmt_last.out

@@ -1,7 +0,0 @@
-vlib/v/checker/tests/match_expr_non_void_stmt_last.vv:9:4: error: `match` expression requires an expression as the last statement of every branch
-    7 |         }
-    8 |         []int {
-    9 |             return arr.str()
-      |             ~~~~~~~~~~~~~~~~
-   10 |         }
-   11 |     }

vlib/v/gen/c/cgen.v

@@ -1737,7 +1737,9 @@ fn (mut g Gen) stmts_with_tmp_var(stmts []ast.Stmt, tmp_var string) bool {
 				g.set_current_pos_as_last_stmt_pos()
 				g.skip_stmt_pos = true
 				mut is_noreturn := false
-				if stmt is ast.ExprStmt {
+				if stmt is ast.Return {
+					is_noreturn = true
+				} else if stmt is ast.ExprStmt {
 					is_noreturn = is_noreturn_callexpr(stmt.expr)
 				}
 				if !is_noreturn {

vlib/v/gen/c/if.v

@@ -23,6 +23,8 @@ fn (mut g Gen) need_tmp_var_in_if(node ast.IfExpr) bool {
 					if g.need_tmp_var_in_expr(stmt.expr) {
 						return true
 					}
+				} else if branch.stmts[0] is ast.Return {
+					return true
 				}
 			}
 		}

vlib/v/gen/c/match.v

@@ -27,6 +27,8 @@ fn (mut g Gen) need_tmp_var_in_match(node ast.MatchExpr) bool {
 					if g.need_tmp_var_in_expr(stmt.expr) {
 						return true
 					}
+				} else if branch.stmts[0] is ast.Return {
+					return true
 				}
 			}
 		}

vlib/v/tests/match_expr_with_branch_returning_1_test.v

@@ -11,7 +11,9 @@ fn (arr Arr) str() string {
 	}
 }
 
-fn main() {
+fn test_match_expr_with_branch_returning() {
 	println(Arr([0, 0]))
+	assert '${Arr([0, 0])}' == '[0, 0]'
 	println(Arr(['0', '0']))
+	assert '${Arr(['0', '0'])}' == '0 0'
 }

vlib/v/tests/match_expr_with_branch_returning_2_test.v

@@ -0,0 +1,19 @@
+fn foo() ! {
+	a := match true {
+		true {
+			2
+		}
+		2 == 2 {
+			return error('hello')
+		}
+		else {
+			0
+		}
+	}
+	println(a)
+	assert a == 2
+}
+
+fn test_match_expr_with_branch_returning() {
+	foo()!
+}