From aa5b609d9555400128b531d2c7ef8de0af7d4924 Mon Sep 17 00:00:00 2001
From: shadowninja55 <49539636+shadowninja55@users.noreply.github.com>
Date: Fri, 9 Jul 2021 07:02:10 -0400
Subject: [PATCH] checker: check integer literals (#10706)

---
 vlib/v/checker/check_types.v               | 25 ++++++++++++++++++++++
 vlib/v/checker/checker.v                   |  2 +-
 vlib/v/checker/tests/oversized_int_lit.out |  8 +++++++
 vlib/v/checker/tests/oversized_int_lit.vv  |  2 ++
 4 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/checker/tests/oversized_int_lit.out
 create mode 100644 vlib/v/checker/tests/oversized_int_lit.vv

diff --git a/vlib/v/checker/check_types.v b/vlib/v/checker/check_types.v
index 6b0e34a176..c4bac909c6 100644
--- a/vlib/v/checker/check_types.v
+++ b/vlib/v/checker/check_types.v
@@ -487,6 +487,31 @@ pub fn (mut c Checker) string_inter_lit(mut node ast.StringInterLiteral) ast.Typ
 	return ast.string_type
 }
 
+pub fn (mut c Checker) int_lit(mut node ast.IntegerLiteral) ast.Type {
+	if node.val.len < 17 {
+		// can not be a too large number, no need for more expensive checks
+		return ast.int_literal_type
+	}
+	lit := node.val.replace('_', '').all_after('-')
+	is_neg := node.val.starts_with('-')
+	limit := if is_neg { '9223372036854775808' } else { '18446744073709551615' }
+	message := 'integer literal $node.val overflows int'
+
+	if lit.len > limit.len {
+		c.error(message, node.pos)
+	} else if lit.len == limit.len {
+		for i, digit in lit {
+			if digit > limit[i] {
+				c.error(message, node.pos)
+			} else if digit < limit[i] {
+				break
+			}
+		}
+	}
+
+	return ast.int_literal_type
+}
+
 pub fn (mut c Checker) infer_fn_generic_types(f ast.Fn, mut call_expr ast.CallExpr) {
 	mut inferred_types := []ast.Type{}
 	for gi, gt_name in f.generic_names {
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 17519d80e6..edae74653b 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -5004,7 +5004,7 @@ pub fn (mut c Checker) expr(node ast.Expr) ast.Type {
 			return c.infix_expr(mut node)
 		}
 		ast.IntegerLiteral {
-			return ast.int_literal_type
+			return c.int_lit(mut node)
 		}
 		ast.LockExpr {
 			return c.lock_expr(mut node)
diff --git a/vlib/v/checker/tests/oversized_int_lit.out b/vlib/v/checker/tests/oversized_int_lit.out
new file mode 100644
index 0000000000..30a9622631
--- /dev/null
+++ b/vlib/v/checker/tests/oversized_int_lit.out
@@ -0,0 +1,8 @@
+vlib/v/checker/tests/oversized_int_lit.vv:1:8: error: integer literal 18446744073709551616 overflows int
+    1 | assert 18446744073709551616 > 0
+      |        ~~~~~~~~~~~~~~~~~~~~
+    2 | assert -9223372036854775809 < 0
+vlib/v/checker/tests/oversized_int_lit.vv:2:8: error: integer literal -9223372036854775809 overflows int
+    1 | assert 18446744073709551616 > 0
+    2 | assert -9223372036854775809 < 0
+      |        ~~~~~~~~~~~~~~~~~~~~
diff --git a/vlib/v/checker/tests/oversized_int_lit.vv b/vlib/v/checker/tests/oversized_int_lit.vv
new file mode 100644
index 0000000000..d6e3a27628
--- /dev/null
+++ b/vlib/v/checker/tests/oversized_int_lit.vv
@@ -0,0 +1,2 @@
+assert 18446744073709551616 > 0
+assert -9223372036854775809 < 0