std/build: support --color

lib/std/build.zig

@@ -45,6 +45,7 @@ pub const Builder = struct {
     verbose_llvm_ir: bool,
     verbose_cimport: bool,
     verbose_llvm_cpu_features: bool,
+    color: enum { auto, on, off } = .auto,
     invalid_user_input: bool,
     zig_exe: []const u8,
     default_step: *Step,
@@ -1946,6 +1947,11 @@ pub const LibExeObjStep = struct {
         };
         zig_args.append(cmd) catch unreachable;
 
+        if (builder.color != .auto) {
+            try zig_args.append("--color");
+            try zig_args.append(@tagName(builder.color));
+        }
+
         if (self.root_src) |root_src| try zig_args.append(root_src.getPath(builder));
 
         var prev_has_extra_flags = false;

lib/std/special/build_runner.zig

@@ -82,6 +82,15 @@ pub fn main() !void {
                     return usageAndErr(builder, false, stderr_stream);
                 };
                 builder.addSearchPrefix(search_prefix);
+            } else if (mem.eql(u8, arg, "--color")) {
+                const next_arg = nextArg(args, &arg_idx) orelse {
+                    warn("expected [auto|on|off] after --color", .{});
+                    return usageAndErr(builder, false, stderr_stream);
+                };
+                builder.color = std.meta.stringToEnum(@TypeOf(builder.color), next_arg) orelse {
+                    warn("expected [auto|on|off] after --color, found '{}'", .{next_arg});
+                    return usageAndErr(builder, false, stderr_stream);
+                };
             } else if (mem.eql(u8, arg, "--override-lib-dir")) {
                 builder.override_lib_dir = nextArg(args, &arg_idx) orelse {
                     warn("Expected argument after --override-lib-dir\n\n", .{});
@@ -171,6 +180,7 @@ fn usage(builder: *Builder, already_ran_build: bool, out_stream: anytype) !void
         \\  --verbose                   Print commands before executing them
         \\  --prefix [path]             Override default install prefix
         \\  --search-prefix [path]      Add a path to look for binaries, libraries, headers
+        \\  --color [auto|off|on]       Enable or disable colored error messages
         \\
         \\Project-Specific Options:
         \\

src/Compilation.zig

@@ -103,7 +103,7 @@ owned_link_dir: ?std.fs.Dir,
 
 /// This is for stage1 and should be deleted upon completion of self-hosting.
 /// Don't use this for anything other than stage1 compatibility.
-color: @import("main.zig").Color = .Auto,
+color: @import("main.zig").Color = .auto,
 
 test_filter: ?[]const u8,
 test_name_prefix: ?[]const u8,
@@ -385,7 +385,7 @@ pub const InitOptions = struct {
     machine_code_model: std.builtin.CodeModel = .default,
     clang_preprocessor_mode: ClangPreprocessorMode = .no,
     /// This is for stage1 and should be deleted upon completion of self-hosting.
-    color: @import("main.zig").Color = .Auto,
+    color: @import("main.zig").Color = .auto,
     test_filter: ?[]const u8 = null,
     test_name_prefix: ?[]const u8 = null,
     subsystem: ?std.Target.SubSystem = null,
@@ -1179,7 +1179,7 @@ pub fn performAllTheWork(self: *Compilation) error{ TimerUnsupported, OutOfMemor
     var progress: std.Progress = .{};
     var main_progress_node = try progress.start("", null);
     defer main_progress_node.end();
-    if (self.color == .Off) progress.terminal = null;
+    if (self.color == .off) progress.terminal = null;
 
     var c_comp_progress_node = main_progress_node.start("Compile C Objects", self.c_source_files.len);
     defer c_comp_progress_node.end();

src/main.zig

@@ -28,9 +28,9 @@ pub fn fatal(comptime format: []const u8, args: anytype) noreturn {
 pub const max_src_size = 2 * 1024 * 1024 * 1024; // 2 GiB
 
 pub const Color = enum {
-    Auto,
-    Off,
-    On,
+    auto,
+    off,
+    on,
 };
 
 const usage =
@@ -380,7 +380,7 @@ fn buildOutputType(
         run,
     },
 ) !void {
-    var color: Color = .Auto;
+    var color: Color = .auto;
     var optimize_mode: std.builtin.Mode = .Debug;
     var provided_name: ?[]const u8 = null;
     var link_mode: ?std.builtin.LinkMode = null;
@@ -585,15 +585,9 @@ fn buildOutputType(
                         }
                         i += 1;
                         const next_arg = args[i];
-                        if (mem.eql(u8, next_arg, "auto")) {
-                            color = .Auto;
-                        } else if (mem.eql(u8, next_arg, "on")) {
-                            color = .On;
-                        } else if (mem.eql(u8, next_arg, "off")) {
-                            color = .Off;
-                        } else {
+                        color = std.meta.stringToEnum(Color, next_arg) orelse {
                             fatal("expected [auto|on|off] after --color, found '{}'", .{next_arg});
-                        }
+                        };
                     } else if (mem.eql(u8, arg, "--subsystem")) {
                         if (i + 1 >= args.len) fatal("expected parameter after {}", .{arg});
                         i += 1;
@@ -2374,7 +2368,7 @@ const Fmt = struct {
 
 pub fn cmdFmt(gpa: *Allocator, args: []const []const u8) !void {
     const stderr_file = io.getStdErr();
-    var color: Color = .Auto;
+    var color: Color = .auto;
     var stdin_flag: bool = false;
     var check_flag: bool = false;
     var input_files = ArrayList([]const u8).init(gpa);
@@ -2394,15 +2388,9 @@ pub fn cmdFmt(gpa: *Allocator, args: []const []const u8) !void {
                     }
                     i += 1;
                     const next_arg = args[i];
-                    if (mem.eql(u8, next_arg, "auto")) {
-                        color = .Auto;
-                    } else if (mem.eql(u8, next_arg, "on")) {
-                        color = .On;
-                    } else if (mem.eql(u8, next_arg, "off")) {
-                        color = .Off;
-                    } else {
+                    color = std.meta.stringToEnum(Color, next_arg) orelse {
                         fatal("expected [auto|on|off] after --color, found '{}'", .{next_arg});
-                    }
+                    };
                 } else if (mem.eql(u8, arg, "--stdin")) {
                     stdin_flag = true;
                 } else if (mem.eql(u8, arg, "--check")) {
@@ -2626,9 +2614,9 @@ fn printErrMsgToFile(
     color: Color,
 ) !void {
     const color_on = switch (color) {
-        .Auto => file.isTty(),
-        .On => true,
-        .Off => false,
+        .auto => file.isTty(),
+        .on => true,
+        .off => false,
     };
     const lok_token = parse_error.loc();
     const span_first = lok_token;