From aaf3ced7501049308448ff99727df84f100c38e2 Mon Sep 17 00:00:00 2001
From: SleepyRoy <47302112+SleepyRoy@users.noreply.github.com>
Date: Wed, 19 Feb 2020 05:14:52 +0800
Subject: [PATCH] parser: add type check for +=, -=, *=, /=

---
 vlib/compiler/aparser.v | 15 +++++++++++++++
 vlib/compiler/table.v   |  5 +++++
 2 files changed, 20 insertions(+)

diff --git a/vlib/compiler/aparser.v b/vlib/compiler/aparser.v
index 446b47328f..2c74b2a314 100644
--- a/vlib/compiler/aparser.v
+++ b/vlib/compiler/aparser.v
@@ -1674,6 +1674,21 @@ fn ($v.name mut $v.typ) ${p.cur_fn.name}(...) {
 		}
 		p.cgen.resetln('memcpy( (& $left), ($etype{$expr}), sizeof( $left ) );')
 	}
+	// check type for +=, -=, *=, /=. 
+	else if tok in [.plus_assign, .minus_assign, .mult_assign, .div_assign] {
+		// special 1. ptrs with += or -= are acceptable.
+		if !(tok in [.plus_assign, .minus_assign] && (is_integer_type(p.assigned_type) || is_pointer_type(p.assigned_type)) && (is_integer_type(expr_type) || is_pointer_type(expr_type))) {
+			// special 2. `str += str` is acceptable 
+			if !(tok == .plus_assign && p.assigned_type == expr_type && expr_type == 'string' ) {
+				if !is_number_type(p.assigned_type) {
+					p.error_with_token_index('cannot use assignment operator ${tok.str()} on non-numeric type `$p.assigned_type`', errtok)
+				}
+				if !is_number_type(expr_type) {
+					p.error_with_token_index('cannot use non-numeric type `$expr_type` as assignment operator ${tok.str()} argument', errtok)
+				}
+			}
+		}
+	}
 	// check type for <<= >>= %= ^= &= |=
 	else if tok in [.left_shift_assign, .righ_shift_assign, .mod_assign, .xor_assign, .and_assign, .or_assign] {
 		if !is_integer_type(p.assigned_type) {
diff --git a/vlib/compiler/table.v b/vlib/compiler/table.v
index e4ca5e1eb9..52ed2419d7 100644
--- a/vlib/compiler/table.v
+++ b/vlib/compiler/table.v
@@ -189,6 +189,7 @@ const (
 	integer_types = ['int', 'i8', 'char', 'byte', 'i16', 'u16', 'u32', 'i64', 'u64']
 	float_types = ['f32', 'f64']
 	reserved_type_param_names = ['R', 'S', 'T', 'U', 'W']
+	pointer_types = ['byte*', 'byteptr', 'char*', 'charptr', 'void*', 'voidptr', 'voidptr*', 'intptr']
 )
 
 fn is_number_type(typ string) bool {
@@ -207,6 +208,10 @@ fn is_primitive_type(typ string) bool {
 	return is_number_type(typ) || typ == 'string'
 }
 
+fn is_pointer_type(typ string) bool {
+    return typ in pointer_types
+}
+
 /*
 fn (t mut Table) register_enum_val(typ, val string) {
 	if t.enum_vals.len == 0 {