import std

Signed-off-by: Slendi <slendi@socopon.com>

nix/cmake-importstd-patched/package.nix

@@ -0,0 +1,37 @@
+# Dummy cmake package for replacing the ImportStd module.
+# Symlink existing derivation to avoid rebuilding package from source.
+# I.e. rather than using overlay or override(Attr) to add patch.
+#
+# Note this is actually a clang/llvm issue (`-print-file-name` flag not working),
+# but it is much simpler to just patch the cmake module itself. Maybe fixed in llvm 19.1.7
+#
+# See relevant issues:
+# 1. https://github.com/NixOS/nixpkgs/issues/370217
+# 2. https://gitlab.kitware.com/cmake/cmake/-/issues/25965#note_1523575
+{
+  lib,
+  cmake,
+  libcxx,
+  symlinkJoin,
+}:
+let
+  cmake-ver = "${lib.versions.majorMinor cmake.version}";
+  module-path = "share/cmake-${cmake-ver}/Modules/Compiler/Clang-CXX-CXXImportStd.cmake";
+in
+symlinkJoin {
+  name = "${cmake.name}-importstd-module-patched";
+  paths = [ cmake ];
+  postBuild = ''
+    # copy binaries to avoid using original derivation
+    for link in $(find $out/bin/ -type l); do
+      cp --remove-destination $(readlink $link) $out/bin/
+    done;
+
+    # replace symlink to existing module with copy for editing
+    cp --remove-destination $(readlink $out/${module-path}) $out/${module-path}
+
+    # replace "libc++.modules.json" with full path
+    # to libc++ module json in new copied module file
+    sed -i 's#libc++.modules.json#${libcxx}/lib/libc++.modules.json#' $out/${module-path}
+  '';
+}