build: probabilistic inconsistent cache state on Windows (repeatedly AccessDenied) from modifying build.zig during running zig build runcmiti

[matu3ba]

Zig Version

0.12.0-dev.2046+d3a163f86
Windows 10.0.19045 (has POSIX file operations support) [latest Windows 10]

Steps to Reproduce and Observed Behavior

git clone https://github.com/matu3ba/win32k-mitigation
cd win32k-mitigation
git checkout ae39165edc07f79783874b0680387a1d578c2c65

Ca. 20-30% trigger chance to get into state, where "zig build runcmiti" fails deterministically and every time. I have edited the file usually after 0.75s and saving takes ~1s due to ?zig.vim on windows shennanigans? (where it asks for key to press).

diff --git a/build.zig b/build.zig
index 0594aae..1dfc7c4 100644
--- a/build.zig
+++ b/build.zig
@@ -124,7 +124,7 @@ pub fn build(b: *std.Build) void {
         // 5. Observe deterministically
         // $ zig build runcmiti
         // error: failed to rename compilation results ('C:\Users\user\dev\zi\win32k-mitigation\zig-cache\tmp\15adb3c4a03dd078') into local cache ('C:\Users\user\dev\zi\win32k-mitigation\zig-cache\o\0df9a39edc521d2b17c1fd98d3777908'): AccessDenied
-        run_win32k_mitigation_c_test.expectExitCode(1);
+        run_win32k_mitigation_c_test.expectExitCode(0);
 
         run_step_cmiti.dependOn(&run_win32k_mitigation_c_test.step);
     }

# powershell
rm -fo -r .\zig-cache\
rm -fo -r .\zig-out\
zig build runcmiti
git apply --ignore-whitespace b.diff
zig build runcmiti

Result in 20-30% of cases repeatedly infinitely (sometimes it did recover):

$ zig build runcmiti
error: failed to rename compilation results ('C:\Users\user\dev\zi\win32k-mitigation\zig-cache\tmp\15adb3c4a03dd078') into local cache ('C:\Users\user\dev\zi\win32k-mitigation\zig-cache\o\0df9a39edc521d2b17c1fd98d3777908'): AccessDenied

Expected Behavior

No repeatedly AccessDenied from zig build runcmiti.

[matu3ba]

Possibly solved by fixing #18450.

[ndbn]

@matu3ba please recheck with >= 0.12.0-dev.2330

[ypsvlq]

fixed by #18637