Merge pull request #24227 from mlugg/misc-build-stuff

`std.Build`: more miscellaneous bits

Author: mlugg

lib/std/Build/Step/Run.zig

@@ -204,11 +204,10 @@ pub fn setName(run: *Run, name: []const u8) void {
 
 pub fn enableTestRunnerMode(run: *Run) void {
     const b = run.step.owner;
-    const arena = b.allocator;
     run.stdio = .zig_test;
+    run.addPrefixedDirectoryArg("--cache-dir=", .{ .cwd_relative = b.cache_root.path orelse "." });
     run.addArgs(&.{
-        std.fmt.allocPrint(arena, "--seed=0x{x}", .{b.graph.random_seed}) catch @panic("OOM"),
-        std.fmt.allocPrint(arena, "--cache-dir={s}", .{b.cache_root.path orelse ""}) catch @panic("OOM"),
+        b.fmt("--seed=0x{x}", .{b.graph.random_seed}),
         "--listen=-",
     });
 }

test/standalone/build.zig.zon

@@ -204,6 +204,9 @@
         .entry_point = .{
             .path = "entry_point",
         },
+        .run_cwd = .{
+            .path = "run_cwd",
+        },
     },
     .paths = .{
         "build.zig",