From cf015e507379c30f9510be5a189ce0d2b1015729 Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipe@php.net>
Date: Tue, 6 Dec 2022 12:27:59 -0300
Subject: [PATCH] checker: add clearer errors for `break`/`continue` used
 within a `$for` loop (#16600)

---
 vlib/v/checker/checker.v                      |  6 +++-
 ...heck_wrong_usage_of_break_and_continue.out | 28 +++++++++++++++++++
 ...check_wrong_usage_of_break_and_continue.vv | 19 +++++++++++++
 vlib/v/tests/comptime_for_break_test.v        | 17 +++++++++++
 4 files changed, 69 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/checker/tests/check_wrong_usage_of_break_and_continue.out
 create mode 100644 vlib/v/checker/tests/check_wrong_usage_of_break_and_continue.vv
 create mode 100644 vlib/v/tests/comptime_for_break_test.v

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 1df582cddb..eb2c7927e2 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -1828,7 +1828,11 @@ fn (mut c Checker) branch_stmt(node ast.BranchStmt) {
 		c.error('`${node.kind.str()}` is not allowed in defer statements', node.pos)
 	}
 	if c.in_for_count == 0 {
-		c.error('${node.kind.str()} statement not within a loop', node.pos)
+		if c.inside_comptime_for_field {
+			c.error('${node.kind.str()} is not allowed within a compile-time loop', node.pos)
+		} else {
+			c.error('${node.kind.str()} statement not within a loop', node.pos)
+		}
 	}
 	if node.label.len > 0 {
 		if node.label != c.loop_label {
diff --git a/vlib/v/checker/tests/check_wrong_usage_of_break_and_continue.out b/vlib/v/checker/tests/check_wrong_usage_of_break_and_continue.out
new file mode 100644
index 0000000000..e8851f46c8
--- /dev/null
+++ b/vlib/v/checker/tests/check_wrong_usage_of_break_and_continue.out
@@ -0,0 +1,28 @@
+vlib/v/checker/tests/check_wrong_usage_of_break_and_continue.vv:9:3: error: continue is not allowed within a compile-time loop
+    7 |     $for field in Test.fields {
+    8 |         println(field)
+    9 |         continue
+      |         ~~~~~~~~
+   10 |     }
+   11 |     $for field in Test.fields {
+vlib/v/checker/tests/check_wrong_usage_of_break_and_continue.vv:13:3: error: break is not allowed within a compile-time loop
+   11 |     $for field in Test.fields {
+   12 |         println(field)
+   13 |         break
+      |         ~~~~~
+   14 |     }
+   15 |     {
+vlib/v/checker/tests/check_wrong_usage_of_break_and_continue.vv:16:3: error: break statement not within a loop
+   14 |     }
+   15 |     {
+   16 |         break
+      |         ~~~~~
+   17 |         continue
+   18 |     }
+vlib/v/checker/tests/check_wrong_usage_of_break_and_continue.vv:17:3: error: continue statement not within a loop
+   15 |     {
+   16 |         break
+   17 |         continue
+      |         ~~~~~~~~
+   18 |     }
+   19 | }
diff --git a/vlib/v/checker/tests/check_wrong_usage_of_break_and_continue.vv b/vlib/v/checker/tests/check_wrong_usage_of_break_and_continue.vv
new file mode 100644
index 0000000000..dc67a6465e
--- /dev/null
+++ b/vlib/v/checker/tests/check_wrong_usage_of_break_and_continue.vv
@@ -0,0 +1,19 @@
+struct Test {
+	a string
+	b string
+}
+
+fn main() {
+	$for field in Test.fields {
+		println(field)
+		continue
+	}
+	$for field in Test.fields {
+		println(field)
+		break
+	}
+	{
+		break
+		continue
+	}
+}
\ No newline at end of file
diff --git a/vlib/v/tests/comptime_for_break_test.v b/vlib/v/tests/comptime_for_break_test.v
new file mode 100644
index 0000000000..d9be41eb08
--- /dev/null
+++ b/vlib/v/tests/comptime_for_break_test.v
@@ -0,0 +1,17 @@
+struct Test {
+	a string
+	b string
+}
+
+fn test_for() {
+	$for field in Test.fields {
+		for attr in field.attrs {
+			break
+		}
+	}
+	$for field in Test.fields {
+		for attr in field.attrs {
+			continue
+		}
+	}
+}