Replace YES_COLOR with CLICOLOR_FORCE

Instead of introducing YES_COLOR, a completely new standard, into the mix
it might make more sense to instead tag along with the CLICOLOR_FORCE env var,
which dates back to at least 2000 with FreeBSD 4.1.1 and which is
supported by tools like CMake.

<https://bixense.com/clicolors/>

lib/compiler/build_runner.zig

@@ -285,7 +285,7 @@ pub fn main() !void {
     const ttyconf = get_tty_conf(color, stderr);
     switch (ttyconf) {
         .no_color => try graph.env_map.put("NO_COLOR", "1"),
-        .escape_codes => try graph.env_map.put("YES_COLOR", "1"),
+        .escape_codes => try graph.env_map.put("CLICOLOR_FORCE", "1"),
         .windows_api => {},
     }
 

lib/std/io/tty.zig

@@ -7,13 +7,13 @@ const native_os = builtin.os.tag;
 
 /// Detect suitable TTY configuration options for the given file (commonly stdout/stderr).
 /// This includes feature checks for ANSI escape codes and the Windows console API, as well as
-/// respecting the `NO_COLOR` and `YES_COLOR` environment variables to override the default.
+/// respecting the `NO_COLOR` and `CLICOLOR_FORCE` environment variables to override the default.
 pub fn detectConfig(file: File) Config {
     const force_color: ?bool = if (builtin.os.tag == .wasi)
         null // wasi does not support environment variables
     else if (process.hasEnvVarConstant("NO_COLOR"))
         false
-    else if (process.hasEnvVarConstant("YES_COLOR"))
+    else if (process.hasEnvVarConstant("CLICOLOR_FORCE"))
         true
     else
         null;

lib/std/zig.zig

@@ -1060,6 +1060,7 @@ pub const EnvVar = enum {
     ZIG_DEBUG_CMD,
     CC,
     NO_COLOR,
+    CLICOLOR_FORCE,
     XDG_CACHE_HOME,
     HOME,
 

src/main.zig

@@ -994,11 +994,16 @@ fn buildOutputType(
         .native_system_include_paths = &.{},
     };
 
-    // before arg parsing, check for the NO_COLOR environment variable
-    // if it exists, default the color setting to .off
+    // before arg parsing, check for the NO_COLOR and CLICOLOR_FORCE environment variables
+    // if set, default the color setting to .off or .on, respectively
     // explicit --color arguments will still override this setting.
     // Disable color on WASI per https://github.com/WebAssembly/WASI/issues/162
-    var color: Color = if (native_os == .wasi or EnvVar.NO_COLOR.isSet()) .off else .auto;
+    var color: Color = if (native_os == .wasi or EnvVar.NO_COLOR.isSet())
+        .off
+    else if (EnvVar.CLICOLOR_FORCE.isSet())
+        .on
+    else
+        .auto;
 
     switch (arg_mode) {
         .build, .translate_c, .zig_test, .run => {

test/src/StackTrace.zig

@@ -61,7 +61,7 @@ fn addExpect(
     });
 
     const run = b.addRunArtifact(exe);
-    run.removeEnvironmentVariable("YES_COLOR");
+    run.removeEnvironmentVariable("CLICOLOR_FORCE");
     run.setEnvironmentVariable("NO_COLOR", "1");
     run.expectExitCode(1);
     run.expectStdOutEqual("");

tools/doctest.zig

@@ -104,7 +104,7 @@ fn printOutput(
     tmp_dir_path: []const u8,
 ) !void {
     var env_map = try process.getEnvMap(arena);
-    try env_map.put("YES_COLOR", "1");
+    try env_map.put("CLICOLOR_FORCE", "1");
 
     const host = try std.zig.system.resolveTargetQuery(.{});
     const obj_ext = builtin.object_format.fileExt(builtin.cpu.arch);