std.debug.lockStderrWriter: also return ttyconf

`std.Io.tty.Config.detect` may be an expensive check (e.g. involving
syscalls), and doing it every time we need to print isn't really
necessary; under normal usage, we can compute the value once and cache
it for the whole program's execution. Since anyone outputting to stderr
may reasonably want this information (in fact they are very likely to),
it makes sense to cache it and return it from `lockStderrWriter`. Call
sites who do not need it will experience no significant overhead, and
can just ignore the TTY config with a `const w, _` destructure.

1 files changed, 5 insertions, 6 deletions

diff --git a/lib/std/Build/Step/Compile.zig b/lib/std/Build/Step/Compile.zig
index 2188d8bfc7..a5f2d696be 100644
--- a/lib/std/Build/Step/Compile.zig
+++ b/lib/std/Build/Step/Compile.zig
@@ -1056,15 +1056,15 @@ fn getGeneratedFilePath(compile: *Compile, comptime tag_name: []const u8, asking
     const maybe_path: ?*GeneratedFile = @field(compile, tag_name);
 
     const generated_file = maybe_path orelse {
-        const w = std.debug.lockStderrWriter(&.{});
-        std.Build.dumpBadGetPathHelp(&compile.step, w, .detect(.stderr()), compile.step.owner, asking_step) catch {};
+        const w, const ttyconf = std.debug.lockStderrWriter(&.{});
+        std.Build.dumpBadGetPathHelp(&compile.step, w, ttyconf, compile.step.owner, asking_step) catch {};
         std.debug.unlockStderrWriter();
         @panic("missing emit option for " ++ tag_name);
     };
 
     const path = generated_file.path orelse {
-        const w = std.debug.lockStderrWriter(&.{});
-        std.Build.dumpBadGetPathHelp(&compile.step, w, .detect(.stderr()), compile.step.owner, asking_step) catch {};
+        const w, const ttyconf = std.debug.lockStderrWriter(&.{});
+        std.Build.dumpBadGetPathHelp(&compile.step, w, ttyconf, compile.step.owner, asking_step) catch {};
         std.debug.unlockStderrWriter();
         @panic(tag_name ++ " is null. Is there a missing step dependency?");
     };
@@ -2027,10 +2027,9 @@ fn checkCompileErrors(compile: *Compile) !void {
         var aw: std.Io.Writer.Allocating = .init(arena);
         defer aw.deinit();
         try actual_eb.renderToWriter(.{
-            .ttyconf = .no_color,
             .include_reference_trace = false,
             .include_source_line = false,
-        }, &aw.writer);
+        }, &aw.writer, .no_color);
         break :ae try aw.toOwnedSlice();
     };