Fixed macro hash_vec(vec): it was checking only the first bytes (4 or 8, not sure) (#2718)

* Fixed macro hash_vec(vec): it was checking only 8 bytes

* use $sizeof() directly as it is correct now

* Added unit test for vector types

Tests that hashes match for same values and that they don't match
when changing a single bit on any of the vector elements

* Changed hardcoded value for the compiler option

* Release note

---------

Co-authored-by: Christoffer Lerno <christoffer@aegik.com>

lib/std/core/builtin.c3

@@ -700,7 +700,7 @@ macro uint hash_array(array_ptr) @local
 *>
 macro uint hash_vec(vec) @local
 {
-	var $len = $sizeof(vec.len * $typeof(vec).inner.sizeof);
+	var $len = $sizeof(vec);
 
 	$if $len > 16:
 		return (uint)komi::hash(((char*)&&vec)[:$len]);

releasenotes.md

@@ -58,6 +58,7 @@
 - Creating recursive debug info for functions could cause assertions.
 - bitorder::read and bitorder::write may fail because of unaligned access #2734.
 - Fix `LinkedList.to_format` to properly iterate linked list for printing.
+- Hashing a vector would not use the entire vector in some cases.
 
 ### Stdlib changes
 - Add `ThreadPool` join function to wait for all threads to finish in the pool without destroying the threads.

test/unit/stdlib/core/builtintests.c3

@@ -174,6 +174,63 @@ fn void test_hash_repeat()
 	assert(int.typeid.hash() == int.typeid.hash());
 }
 
+macro test_hash_vector_macro(...)
+{
+	int[] $lens = {1, 2, 4, 7, 8, 13, 16, 23, 32, 43, 64, 103};
+	$for var $i = 0; $i < $vacount ; $i++:
+	{
+		$foreach $vec_len : $lens:
+		{
+			$if $vec_len * $vatype[$i].sizeof * 8  <= $$MAX_VECTOR_SIZE:
+			{
+				$vatype[$i][<$vec_len>] vec1, vec2;
+				for (int val = 0; val < $vec_len; val++)
+				{
+					$vatype[$i] tval = ($vatype[$i])val;
+					vec1[val] = (tval | (tval << (($vatype[$i].sizeof - 1) * 8)));
+				}
+				vec2 = vec1;
+				assert(vec1.hash() == vec2.hash(), "hashes don't match for %s and %s", vec1, vec2);
+				for (int val = 0; val < $vec_len; val++)
+				{
+					vec2[val] ^= (($vatype[$i])0b0010_0000 << (($vatype[$i].sizeof - 1) * 8));
+					assert(vec1.hash() != vec2.hash(), "hashes match for %s and %s", vec1, vec2);
+					vec2[val] ^= (($vatype[$i])0b0010_0000 << (($vatype[$i].sizeof - 1) * 8));
+				}
+			}
+			$endif
+		}
+		$endforeach
+	}
+	$endfor
+}
+macro test_hash_vector_macro_bool()
+{
+	int[] $lens = {1, 2, 4, 7, 8, 13, 16, 23, 32, 43, 64, 103};
+	$foreach $vec_len : $lens:
+	{
+		bool[<$vec_len>] vec1, vec2;
+		for (int val = 0; val < $vec_len; val++)
+		{
+			vec1[val] = ((val & 0x3) == 0);
+		}
+		vec2 = vec1;
+		assert(vec1.hash() == vec2.hash(), "hashes don't match for %s and %s", vec1, vec2);
+		for (int val = 0; val < $vec_len; val++)
+		{
+			vec2[val] = !vec2[val];
+			assert(vec1.hash() != vec2.hash(), "hashes match for %s and %s", vec1, vec2);
+			vec2[val] = !vec2[val];
+		}
+	}
+	$endforeach
+}
+fn void test_hash_vector()
+{
+	test_hash_vector_macro(char, ichar, short, ushort, int, uint, long, ulong, int128, uint128);
+	test_hash_vector_macro_bool();
+}
+
 fn void test_builtin_string_hashing() => @pool()
 {
 	var $x = "";