From 3d4cd0bbc0db7eee82d8acbad85757082b7941c7 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 10 Jul 2019 16:05:39 +0200
Subject: [PATCH] check integer const overflow at compilation

---
 compiler/parser.v     |  8 ++++++--
 compiler/table.v      | 20 ++++++++++++++++++++
 vlib/builtin/string.v |  4 ++++
 vlib/math/math.v      | 15 +++++++++++++++
 4 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/compiler/parser.v b/compiler/parser.v
index 66ab24ac45..ee6c870d30 100644
--- a/compiler/parser.v
+++ b/compiler/parser.v
@@ -1994,6 +1994,9 @@ fn (p mut Parser) factor() string {
 			typ = 'f32'
 			// typ = 'f64' // TODO 
 		}
+		if p.expected_type != '' && !is_valid_int_const(p.lit, p.expected_type) { 
+			p.error('constant `$p.lit` overflows `$p.expected_type`') 
+		} 
 		p.gen(p.lit)
 		p.fgen(p.lit)
 	case Token.minus:
@@ -2252,7 +2255,7 @@ fn (p mut Parser) string_expr() {
 	// '$age'! means the user wants this to be a tmp string (uses global buffer, no allocation,
 	// won't be used	again)
 	if p.tok == .not {
-		p.next()
+		p.check(.not) 
 		p.gen('_STR_TMP($format$args)')
 	}
 	else {
@@ -2550,7 +2553,9 @@ fn (p mut Parser) cast(typ string) string {
 		p.next()
 	}
 	p.check(.lpar)
+	p.expected_type = typ 
 	expr_typ := p.bool_expression()
+	p.expected_type = '' 
 	p.check(.rpar)
 	// `string(buffer)` => `tos2(buffer)`
 	if typ == 'string' && (expr_typ == 'byte*' || expr_typ == 'byteptr') {
@@ -2562,7 +2567,6 @@ fn (p mut Parser) cast(typ string) string {
 	} 
 	else {
 		p.cgen.set_placeholder(pos, '($typ)(')
-		// p.fgen(typ)
 	}
 	p.gen(')')
 	return typ
diff --git a/compiler/table.v b/compiler/table.v
index dbca9145e4..82a49b1a06 100644
--- a/compiler/table.v
+++ b/compiler/table.v
@@ -4,6 +4,8 @@
 
 module main
 
+import math 
+
 struct Table {
 mut:
 	types     []Type
@@ -637,3 +639,21 @@ fn (table &Table) cgen_name_type_pair(name, typ string) string {
 	return '$typ $name'
 }
 
+fn is_valid_int_const(val, typ string) bool {
+	x := val.int() 
+	switch typ {
+	case 'byte', 'u8': return 0 <= x && x <= math.MaxU8 
+	case 'u16': return 0 <= x && x <= math.MaxU16 
+	case 'u32': return 0 <= x && x <= math.MaxU32 
+	//case 'u64': return 0 <= x && x <= math.MaxU64 
+	////////////// 
+	case 'i8': return math.MinI8 <= x && x <= math.MaxI8 
+	case 'i16': return math.MinI16 <= x && x <= math.MaxI16 
+	case 'int', 'i32': return math.MinI32 <= x && x <= math.MaxI32 
+	//case 'i64': 
+		//x64 := val.i64() 
+		//return i64(-(1<<63)) <= x64 && x64 <= i64((1<<63)-1) 
+	} 
+	return true 
+} 
+
diff --git a/vlib/builtin/string.v b/vlib/builtin/string.v
index f16b32f399..e38447b8f8 100644
--- a/vlib/builtin/string.v
+++ b/vlib/builtin/string.v
@@ -133,6 +133,10 @@ pub fn (s string) int() int {
 	return C.atoi(s.str)
 }
 
+pub fn (s string) i64() i64 {
+	return C.atoll(s.str)
+}
+
 pub fn (s string) f32() f32 {
 	return C.atof(s.str)
 }
diff --git a/vlib/math/math.v b/vlib/math/math.v
index 543109c57a..42063d4301 100644
--- a/vlib/math/math.v
+++ b/vlib/math/math.v
@@ -22,6 +22,21 @@ const (
 	Log10E = 1.0 / Ln10
 )
 
+const (
+        MaxI8   = (1<<7) - 1
+        MinI8   = -1 << 7
+        MaxI16  = (1<<15) - 1
+        MinI16  = -1 << 15
+        MaxI32  = (1<<31) - 1
+        MinI32  = -1 << 31
+//        MaxI64  = ((1<<63) - 1) 
+//        MinI64  = (-(1 << 63) ) 
+        MaxU8  = (1<<8) - 1 
+        MaxU16 = (1<<16) - 1
+        MaxU32 = (1<<32) - 1
+        MaxU64 = (1<<64) - 1
+) 
+
 // Returns the absolute value.
 pub fn abs(a f64) f64 {
 	if a < 0 {