From d3cbbe0b1e38394de5c4ea6efe9372203092002f Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Sun, 5 Mar 2023 16:16:32 -0700
Subject: [PATCH] std.Build.Step: no-op steps report cached if all deps cached

---
 lib/std/Build/Step.zig | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/lib/std/Build/Step.zig b/lib/std/Build/Step.zig
index 1a7fe24e7c..d146ddb259 100644
--- a/lib/std/Build/Step.zig
+++ b/lib/std/Build/Step.zig
@@ -144,9 +144,16 @@ pub fn getStackTrace(s: *Step) std.builtin.StackTrace {
     };
 }
 
-fn makeNoOp(self: *Step, prog_node: *std.Progress.Node) anyerror!void {
-    _ = self;
+fn makeNoOp(step: *Step, prog_node: *std.Progress.Node) anyerror!void {
     _ = prog_node;
+
+    var all_cached = true;
+
+    for (step.dependencies.items) |dep| {
+        all_cached = all_cached and dep.result_cached;
+    }
+
+    step.result_cached = all_cached;
 }
 
 pub fn cast(step: *Step, comptime T: type) ?*T {