mem: explicit Allocator.Error on concat and join

Author: pascaldekloe

lib/std/mem.zig

@@ -2948,18 +2948,18 @@ pub fn SplitBackwardsIterator(comptime T: type, comptime delimiter_type: Delimit
 
 /// Naively combines a series of slices with a separator.
 /// Allocates memory for the result, which must be freed by the caller.
-pub fn join(allocator: Allocator, separator: []const u8, slices: []const []const u8) ![]u8 {
+pub fn join(allocator: Allocator, separator: []const u8, slices: []const []const u8) Allocator.Error![]u8 {
     return joinMaybeZ(allocator, separator, slices, false);
 }
 
 /// Naively combines a series of slices with a separator and null terminator.
 /// Allocates memory for the result, which must be freed by the caller.
-pub fn joinZ(allocator: Allocator, separator: []const u8, slices: []const []const u8) ![:0]u8 {
+pub fn joinZ(allocator: Allocator, separator: []const u8, slices: []const []const u8) Allocator.Error![:0]u8 {
     const out = try joinMaybeZ(allocator, separator, slices, true);
     return out[0 .. out.len - 1 :0];
 }
 
-fn joinMaybeZ(allocator: Allocator, separator: []const u8, slices: []const []const u8, zero: bool) ![]u8 {
+fn joinMaybeZ(allocator: Allocator, separator: []const u8, slices: []const []const u8, zero: bool) Allocator.Error![]u8 {
     if (slices.len == 0) return if (zero) try allocator.dupe(u8, &[1]u8{0}) else &[0]u8{};
 
     const total_len = blk: {
@@ -3038,18 +3038,18 @@ test "joinZ" {
 }
 
 /// Copies each T from slices into a new slice that exactly holds all the elements.
-pub fn concat(allocator: Allocator, comptime T: type, slices: []const []const T) ![]T {
+pub fn concat(allocator: Allocator, comptime T: type, slices: []const []const T) Allocator.Error![]T {
     return concatMaybeSentinel(allocator, T, slices, null);
 }
 
 /// Copies each T from slices into a new slice that exactly holds all the elements.
-pub fn concatWithSentinel(allocator: Allocator, comptime T: type, slices: []const []const T, comptime s: T) ![:s]T {
+pub fn concatWithSentinel(allocator: Allocator, comptime T: type, slices: []const []const T, comptime s: T) Allocator.Error![:s]T {
     const ret = try concatMaybeSentinel(allocator, T, slices, s);
     return ret[0 .. ret.len - 1 :s];
 }
 
 /// Copies each T from slices into a new slice that exactly holds all the elements as well as the sentinel.
-pub fn concatMaybeSentinel(allocator: Allocator, comptime T: type, slices: []const []const T, comptime s: ?T) ![]T {
+pub fn concatMaybeSentinel(allocator: Allocator, comptime T: type, slices: []const []const T, comptime s: ?T) Allocator.Error![]T {
     if (slices.len == 0) return if (s) |sentinel| try allocator.dupe(T, &[1]T{sentinel}) else &[0]T{};
 
     const total_len = blk: {