std: extend mem.{len,toSlice,toSliceConst} to take any sentinel

Author: daurnimator

lib/std/cstr.zig

@@ -28,7 +28,7 @@ test "cstr fns" {
 
 fn testCStrFnsImpl() void {
     testing.expect(cmp("aoeu", "aoez") == -1);
-    testing.expect(mem.len(u8, "123456789") == 9);
+    testing.expect(mem.len(u8, "123456789".*) == 9);
 }
 
 /// Returns a mutable, null-terminated slice with the same length as `slice`.

lib/std/mem.zig

@@ -357,18 +357,21 @@ pub fn eql(comptime T: type, a: []const T, b: []const T) bool {
     return true;
 }
 
-pub fn len(comptime T: type, ptr: [*:0]const T) usize {
+pub fn len(comptime T: type, ptr: var) usize {
+    const sentinel: T = comptime meta.Sentinel(@TypeOf(ptr));
     var count: usize = 0;
-    while (ptr[count] != 0) : (count += 1) {}
+    while (ptr[count] != sentinel) : (count += 1) {}
     return count;
 }
 
-pub fn toSliceConst(comptime T: type, ptr: [*:0]const T) [:0]const T {
-    return ptr[0..len(T, ptr) :0];
+pub fn toSliceConst(comptime T: type, ptr: var) [:meta.Sentinel(@TypeOf(ptr))]const T {
+    const sentinel: T = comptime meta.Sentinel(@TypeOf(ptr));
+    return ptr[0..len(T, ptr) :sentinel];
 }
 
-pub fn toSlice(comptime T: type, ptr: [*:0]T) [:0]T {
-    return ptr[0..len(T, ptr) :0];
+pub fn toSlice(comptime T: type, ptr: var) [:meta.Sentinel(@TypeOf(ptr))]T {
+    const sentinel: T = comptime meta.Sentinel(@TypeOf(ptr));
+    return ptr[0..len(T, ptr) :sentinel];
 }
 
 /// Returns true if all elements in a slice are equal to the scalar value provided

test/stage1/behavior/misc.zig

@@ -365,7 +365,7 @@ test "string concatenation" {
     comptime expect(@TypeOf(a) == *const [12:0]u8);
     comptime expect(@TypeOf(b) == *const [12:0]u8);
 
-    const len = mem.len(u8, b);
+    const len = mem.len(u8, b.*);
     const len_with_null = len + 1;
     {
         var i: u32 = 0;