How to point the build at the right ninja binary?

[rnikander]

I'm following the instructions here, so I can use a newer version of CMake. There are 4 steps there, and 1-3 seem to have worked smoothly. However, at step 4, when I install a newer copy of Ninja (which I need for C++20 modules to work), the NDK build process still uses the version of ninja.exe in its directories.

The build output contains:

C++ build system [configure] failed while executing:
   @echo off
   "C:\\Program Files\\CMake\\bin\\cmake.exe" ^
   ...
   "-DCMAKE_MAKE_PROGRAM=C:\\Users\\rob\\AppData\\Local\\Android\\Sdk\\cmake\\3.22.1\\bin\\ninja.exe" ^
   ...
The Ninja generator does not support C++20 modules using Ninja version
    1.10.2

My ninja is at C:\Users\rob\Workspace\Tools\ninja-win\ninja.exe. It's on my path, and I have restarted Android Studio.

PS C:\Users\rob> ninja --version
1.11.1

Is there something else I can do? Maybe it should be added to that 4th point in the documentation?

[DanAlbert]

As best as I can tell that's set here (I don't know how this works, I just went to the Studio section of cs.android.com and searched for DCMAKE_MAKE_PROGRAM). That seems to eventually call findNinjaPathLogic, whose docs say:

/**
 * Method for locating ninja.exe. The search order is:
 * 1) Folder of CMake.exe, if present
 * 2) Other CMake SDK folders, if present
 * 3) Environment PATH
 */

So the one in your path is only used if you have no other CMake versions installed by the SDK manager. 2 and 3 seem backward to me, but that's another product. File a C++ bug against Studio at https://b.android.com if you want the behavior changed. It's pretty odd that there's not gradle DSL to override that.

[rnikander]

Reported here. The workaround is easy enough. Just copy the ninja.exe to the one the SDK is using.

But, C++20 modules still won't work, because the NDK does not include clang-scan-deps. I see it #1853 as a "feature request". I think that should be considered a bug, not a feature request. Hopefully it's an easy fix, to include the file that is built alongside clang.