From ac442abc11ed15d33299d2bae69c15441212a054 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20D=C3=A4schle?= <daniel.daeschle@gmail.com>
Date: Sun, 29 Aug 2021 10:57:11 +0200
Subject: [PATCH] checker: allow noreturn in match expr (#11126)

---
 vlib/v/checker/checker.v  |  3 ++-
 vlib/v/gen/c/cgen.v       | 15 ++++++++++++++-
 vlib/v/tests/match_test.v | 14 ++++++++++++++
 3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 467b00b4ad..cac3a24fb3 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -6124,7 +6124,8 @@ pub fn (mut c Checker) match_expr(mut node ast.MatchExpr) ast.Type {
 						if !c.check_types(ret_type, expr_type)
 							&& !c.check_types(expr_type, ret_type) {
 							ret_sym := c.table.get_type_symbol(ret_type)
-							if !(node.is_expr && ret_sym.kind == .sum_type) {
+							is_noreturn := is_noreturn_callexpr(stmt.expr)
+							if !(node.is_expr && ret_sym.kind == .sum_type) && !is_noreturn {
 								c.error('return type mismatch, it should be `$ret_sym.name`',
 									stmt.expr.position())
 							}
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index d1035ca052..152d84de82 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -1084,6 +1084,13 @@ fn (mut g Gen) stmts(stmts []ast.Stmt) {
 	g.stmts_with_tmp_var(stmts, '')
 }
 
+fn is_noreturn_callexpr(expr ast.Expr) bool {
+	if expr is ast.CallExpr {
+		return expr.is_noreturn
+	}
+	return false
+}
+
 // tmp_var is used in `if` expressions only
 fn (mut g Gen) stmts_with_tmp_var(stmts []ast.Stmt, tmp_var string) {
 	g.indent++
@@ -1119,7 +1126,13 @@ fn (mut g Gen) stmts_with_tmp_var(stmts []ast.Stmt, tmp_var string) {
 			} else {
 				g.stmt_path_pos << g.out.len
 				g.skip_stmt_pos = true
-				g.write('$tmp_var = ')
+				mut is_noreturn := false
+				if stmt is ast.ExprStmt {
+					is_noreturn = is_noreturn_callexpr(stmt.expr)
+				}
+				if !is_noreturn {
+					g.write('$tmp_var = ')
+				}
 				g.stmt(stmt)
 				if !g.out.last_n(2).contains(';') {
 					g.writeln(';')
diff --git a/vlib/v/tests/match_test.v b/vlib/v/tests/match_test.v
index 32a77b6b1c..25d96e13a7 100644
--- a/vlib/v/tests/match_test.v
+++ b/vlib/v/tests/match_test.v
@@ -287,3 +287,17 @@ fn test_match_expression_add() {
 	} + 3
 	assert a == 4
 }
+
+type LeType = int | string
+
+fn test_noreturn() {
+	t := LeType(3)
+	_ := match t {
+		int {
+			'test'
+		}
+		string {
+			exit(0)
+		}
+	}
+}