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, 2 insertions, 2 deletions

diff --git a/src/InternPool.zig b/src/InternPool.zig
index a595fa502c..2a5436787c 100644
--- a/src/InternPool.zig
+++ b/src/InternPool.zig
@@ -11330,7 +11330,7 @@ fn dumpStatsFallible(ip: *const InternPool, arena: Allocator) anyerror!void {
 
 fn dumpAllFallible(ip: *const InternPool) anyerror!void {
     var buffer: [4096]u8 = undefined;
-    const stderr_bw = std.debug.lockStderrWriter(&buffer);
+    const stderr_bw, _ = std.debug.lockStderrWriter(&buffer);
     defer std.debug.unlockStderrWriter();
     for (ip.locals, 0..) |*local, tid| {
         const items = local.shared.items.view();
@@ -11462,7 +11462,7 @@ pub fn dumpGenericInstancesFallible(ip: *const InternPool, allocator: Allocator)
     }
 
     var buffer: [4096]u8 = undefined;
-    const stderr_bw = std.debug.lockStderrWriter(&buffer);
+    const stderr_bw, _ = std.debug.lockStderrWriter(&buffer);
     defer std.debug.unlockStderrWriter();
 
     const SortContext = struct {