From 82a355131377023c1e9d3557071240e81814b578 Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Thu, 22 Dec 2022 18:55:44 +0800
Subject: [PATCH] checker, cgen: fix match expr with branch returning (#16741)

---
 vlib/v/checker/match.v                        |  2 +-
 .../tests/match_expr_non_void_stmt_last.out   |  7 -------
 vlib/v/gen/c/cgen.v                           |  4 +++-
 vlib/v/gen/c/if.v                             |  2 ++
 vlib/v/gen/c/match.v                          |  2 ++
 ...match_expr_with_branch_returning_1_test.v} |  4 +++-
 .../match_expr_with_branch_returning_2_test.v | 19 +++++++++++++++++++
 7 files changed, 30 insertions(+), 10 deletions(-)
 delete mode 100644 vlib/v/checker/tests/match_expr_non_void_stmt_last.out
 rename vlib/v/{checker/tests/match_expr_non_void_stmt_last.vv => tests/match_expr_with_branch_returning_1_test.v} (62%)
 create mode 100644 vlib/v/tests/match_expr_with_branch_returning_2_test.v

diff --git a/vlib/v/checker/match.v b/vlib/v/checker/match.v
index d7ea150597..f22bc0925c 100644
--- a/vlib/v/checker/match.v
+++ b/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)
diff --git a/vlib/v/checker/tests/match_expr_non_void_stmt_last.out b/vlib/v/checker/tests/match_expr_non_void_stmt_last.out
deleted file mode 100644
index 6b5e1612f9..0000000000
--- a/vlib/v/checker/tests/match_expr_non_void_stmt_last.out
+++ /dev/null
@@ -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 |     }
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 599f9783b8..b4b8cad6cf 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/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 {
diff --git a/vlib/v/gen/c/if.v b/vlib/v/gen/c/if.v
index 2c82ae285a..a5f09fdba0 100644
--- a/vlib/v/gen/c/if.v
+++ b/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
 				}
 			}
 		}
diff --git a/vlib/v/gen/c/match.v b/vlib/v/gen/c/match.v
index 7ccf2a9c70..82389b35ac 100644
--- a/vlib/v/gen/c/match.v
+++ b/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
 				}
 			}
 		}
diff --git a/vlib/v/checker/tests/match_expr_non_void_stmt_last.vv b/vlib/v/tests/match_expr_with_branch_returning_1_test.v
similarity index 62%
rename from vlib/v/checker/tests/match_expr_non_void_stmt_last.vv
rename to vlib/v/tests/match_expr_with_branch_returning_1_test.v
index 0737152b0d..92a3eb9097 100644
--- a/vlib/v/checker/tests/match_expr_non_void_stmt_last.vv
+++ b/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'
 }
diff --git a/vlib/v/tests/match_expr_with_branch_returning_2_test.v b/vlib/v/tests/match_expr_with_branch_returning_2_test.v
new file mode 100644
index 0000000000..9bc9cbe8f3
--- /dev/null
+++ b/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()!
+}