std: Fix broken tests

Author: LemonBoy

lib/std/io.zig

@@ -350,12 +350,18 @@ pub fn BitInStream(endian: builtin.Endian, comptime Error: type) type {
                 switch (endian) {
                     .Big => {
                         out_buffer = @as(Buf, self.bit_buffer >> shift);
-                        self.bit_buffer <<= n;
+                        if (n >= u7_bit_count)
+                            self.bit_buffer = 0
+                        else
+                            self.bit_buffer <<= n;
                     },
                     .Little => {
                         const value = (self.bit_buffer << shift) >> shift;
                         out_buffer = @as(Buf, value);
-                        self.bit_buffer >>= n;
+                        if (n >= u7_bit_count)
+                            self.bit_buffer = 0
+                        else
+                            self.bit_buffer >>= n;
                     },
                 }
                 self.bit_count -= n;

lib/std/mem.zig

@@ -921,6 +921,9 @@ pub fn writeInt(comptime T: type, buffer: *[@divExact(T.bit_count, 8)]u8, value:
 pub fn writeIntSliceLittle(comptime T: type, buffer: []u8, value: T) void {
     assert(buffer.len >= @divExact(T.bit_count, 8));
 
+    if (T.bit_count == 0)
+        return set(u8, buffer, 0);
+
     // TODO I want to call writeIntLittle here but comptime eval facilities aren't good enough
     const uint = std.meta.IntType(false, T.bit_count);
     var bits = @truncate(uint, value);
@@ -938,6 +941,9 @@ pub fn writeIntSliceLittle(comptime T: type, buffer: []u8, value: T) void {
 pub fn writeIntSliceBig(comptime T: type, buffer: []u8, value: T) void {
     assert(buffer.len >= @divExact(T.bit_count, 8));
 
+    if (T.bit_count == 0)
+        return set(u8, buffer, 0);
+
     // TODO I want to call writeIntBig here but comptime eval facilities aren't good enough
     const uint = std.meta.IntType(false, T.bit_count);
     var bits = @truncate(uint, value);
@@ -1807,7 +1813,7 @@ test "sliceAsBytes" {
 }
 
 test "sliceAsBytes with sentinel slice" {
-    const empty_string:[:0]const u8 = "";
+    const empty_string: [:0]const u8 = "";
     const bytes = sliceAsBytes(empty_string);
     testing.expect(bytes.len == 0);
 }