From 5e1a2f6f502b71f14ce7bc5e55a2023c67c7b171 Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Sat, 3 Sep 2022 15:56:46 +0800
Subject: [PATCH] checker: check if guard with multiple return variable
 (#15646)

---
 vlib/v/checker/if.v                           | 29 ++++++++---------
 .../checker/tests/if_guard_variables_err.out  | 31 ++++++++++++-------
 .../v/checker/tests/if_guard_variables_err.vv |  8 +++++
 3 files changed, 42 insertions(+), 26 deletions(-)

diff --git a/vlib/v/checker/if.v b/vlib/v/checker/if.v
index af9a11da5..d36437bf4 100644
--- a/vlib/v/checker/if.v
+++ b/vlib/v/checker/if.v
@@ -54,6 +54,21 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) ast.Type {
 				}
 			}
 		}
+		if mut branch.cond is ast.IfGuardExpr {
+			sym := c.table.sym(branch.cond.expr_type)
+			if sym.kind == .multi_return {
+				mr_info := sym.info as ast.MultiReturn
+				if branch.cond.vars.len != mr_info.types.len {
+					c.error('if guard expects $mr_info.types.len variables, but got $branch.cond.vars.len',
+						branch.pos)
+					continue
+				} else {
+					for vi, var in branch.cond.vars {
+						branch.scope.update_var_type(var.name, mr_info.types[vi])
+					}
+				}
+			}
+		}
 		if node.is_comptime { // Skip checking if needed
 			// smartcast field type on comptime if
 			mut comptime_field_name := ''
@@ -247,20 +262,6 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) ast.Type {
 					branch.pos)
 			}
 		}
-		if mut branch.cond is ast.IfGuardExpr {
-			sym := c.table.sym(branch.cond.expr_type)
-			if sym.kind == .multi_return {
-				mr_info := sym.info as ast.MultiReturn
-				if branch.cond.vars.len != mr_info.types.len {
-					c.error('if guard expects $mr_info.types.len variables, but got $branch.cond.vars.len',
-						branch.pos)
-				} else {
-					for vi, var in branch.cond.vars {
-						branch.scope.update_var_type(var.name, mr_info.types[vi])
-					}
-				}
-			}
-		}
 		// Also check for returns inside a comp.if's statements, even if its contents aren't parsed
 		if has_return := c.has_return(branch.stmts) {
 			if has_return {
diff --git a/vlib/v/checker/tests/if_guard_variables_err.out b/vlib/v/checker/tests/if_guard_variables_err.out
index 4ed3096e3..b9690c6bc 100644
--- a/vlib/v/checker/tests/if_guard_variables_err.out
+++ b/vlib/v/checker/tests/if_guard_variables_err.out
@@ -1,14 +1,21 @@
-vlib/v/checker/tests/if_guard_variables_err.vv:6:2: error: if guard expects 3 variables, but got 1
-    4 |
-    5 | fn main() {
-    6 |     if r1 := create() {
+vlib/v/checker/tests/if_guard_variables_err.vv:10:2: error: if guard expects 3 variables, but got 1
+    8 |
+    9 | fn main() {
+   10 |     if r1 := create() {
       |     ~~~~~~~~~~~~~~~~~
-    7 |         println(r1)
-    8 |     }
-vlib/v/checker/tests/if_guard_variables_err.vv:10:2: error: if guard expects 3 variables, but got 4
-    8 |     }
-    9 |
-   10 |     if r1, r2, r3, r4 := create() {
-      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    11 |         println(r1)
-   12 |         println(r2)
+   12 |     }
+vlib/v/checker/tests/if_guard_variables_err.vv:14:2: error: if guard expects 3 variables, but got 4
+   12 |     }
+   13 |
+   14 |     if r1, r2, r3, r4 := create() {
+      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   15 |         println(r1)
+   16 |         println(r2)
+vlib/v/checker/tests/if_guard_variables_err.vv:21:2: error: if guard expects 2 variables, but got 1
+   19 |     }
+   20 |
+   21 |     if x := maybe() {
+      |     ~~~~~~~~~~~~~~~
+   22 |         println('$x')
+   23 |     }
diff --git a/vlib/v/checker/tests/if_guard_variables_err.vv b/vlib/v/checker/tests/if_guard_variables_err.vv
index dbd042069..c87a8e81b 100644
--- a/vlib/v/checker/tests/if_guard_variables_err.vv
+++ b/vlib/v/checker/tests/if_guard_variables_err.vv
@@ -2,6 +2,10 @@ fn create() ?(int, string, bool) {
 	return 5, 'aa', true
 }
 
+fn maybe() ?(int, int) {
+	return 1, 2
+}
+
 fn main() {
 	if r1 := create() {
 		println(r1)
@@ -13,4 +17,8 @@ fn main() {
 		println(r3)
 		println(r4)
 	}
+
+	if x := maybe() {
+		println('$x')
+	}
 }
-- 
2.30.2