I was able to replicate this with Mesa master too.

Can also replicate with the very short scons gles=1 because osmesa is included in the default configuration.

Found some posts from mailing list that describe this issue:
https://lists.freedesktop.org/archives/mesa-users/2012-May/000431.html
https://lists.freedesktop.org/archives/mesa-users/2016-March/001142.html

Hi Alex,

First off, note that I don't know anything about scons, msvc or windows, but Dylan has been adding Windows support to Meson (https://lists.freedesktop.org/archives/mesa-dev/2018-June/197325.html).

Would you mind testing the work-in-progress branch and report if it works when building with Meson?
git://people.freedesktop.org/~dbaker/mesa meson-windows

Eric, I tried that branch but it's far from being in working state. When I attempt to build it, it tries to find pkg-config. This doesn't make sense for a MSVC build. As far as I know that's a Linux, MSYS2 and Cygwin thing and has nothing to do with MSVC:

The following Python versions were detected:
1. Python 2.7

Note: Experimental /enablemeson command-line argument is set. We will attempt to build Mesa3D if you pick any of the folowing Python versions even if it is known to fail for now:

5. Python 3.6

Select Python version by entering its index from the table above:5

Using Python 3.6.5 from C:\Software\DEVELO~1\projects\mesa\py3\python.exe.

WARNING: Python 3.x support is experimental.

Install/update python packages (y/n):

Begin LLVM build. Only needs to run once for each ABI and version. Proceed (y/n):


Begin mesa build. Proceed (y/n):y

Use Ninja build system instead of MsBuild (y/n); less storage device strain and maybe faster build:

Do you want to clean build (y/n):y


**********************************************************************
** Visual Studio 2017 Developer Command Prompt v15.7.3
** Copyright (c) 2017 Microsoft Corporation
**********************************************************************
[vcvarsall.bat] Environment initialized for: 'x64'

Microsoft Windows [Version 10.0.17134.112]
(c) 2018 Microsoft Corporation. All rights reserved.

C:\Software\DEVELO~1\projects\mesa\mesa>echo %buildcmd%
C:\Software\DEVELO~1\projects\mesa\py3\python.exe C:\Software\DEVELO~1\projects\mesa\py3\Scripts\meson.py . .\build\windows-x86_64 --backend=vs2017 --buildtype=release

C:\Software\DEVELO~1\projects\mesa\mesa>%buildcmd%
The Meson build system
Version: 0.46.1
Source dir: C:\Software\DEVELO~1\projects\mesa\mesa
Build dir: C:\Software\DEVELO~1\projects\mesa\mesa\build\windows-x86_64
Build type: native build
Program python found: YES (C:\Software\DEVELO~1\projects\mesa\py3\python.EXE)
Project name: mesa
Native C compiler: cl (msvc 19.14.26430)
Native C++ compiler: cl (msvc 19.14.26430)
Build machine cpu family: x86_64
Build machine cpu: x86_64
Program pkg-config found: NO

meson.build:414:0: ERROR:  Program(s) ['pkg-config'] not found or not executable

A full log can be found at C:\Software\DEVELO~1\projects\mesa\mesa\build\windows-x86_64\meson-logs\meson-log.txt

C:\Software\DEVELO~1\projects\mesa\mesa>


To test for this issue I probably only have to add -Dshared-glapi=true and Dosmesa=gallium. Dgles1 and Dgles2 are not needed as the only requirement is an osmesa build with shared-glapi. But for those options to have any meaningful effect the build has to get further.

Ping.

(In reply to Eric Engestrom from comment #4)
> Hi Alex,
> Would you mind testing the work-in-progress branch and report if it works
> when building with Meson?
> git://people.freedesktop.org/~dbaker/mesa meson-windows
That branch appears to be incomplete. It has only 24 of the 48 patches in the series:
https://cgit.freedesktop.org/~dbaker/mesa/log/?h=meson-windows
Full series: https://patchwork.freedesktop.org/series/44596/
After looking at the 46th patch in the series that acts like a blueprint I noticed the branch is incomplete.

(In reply to Alex Granni from comment #7)
> (In reply to Eric Engestrom from comment #4)
> > Hi Alex,
> > Would you mind testing the work-in-progress branch and report if it works
> > when building with Meson?
> > git://people.freedesktop.org/~dbaker/mesa meson-windows
> That branch appears to be incomplete. It has only 24 of the 48 patches in
> the series:
> https://cgit.freedesktop.org/~dbaker/mesa/log/?h=meson-windows
> Full series: https://patchwork.freedesktop.org/series/44596/
> After looking at the 46th patch in the series that acts like a blueprint I
> noticed the branch is incomplete.
Dylan posted the Meson windows branch on Freedesktop Gitlab. I'll test this issue with Meson soon.

(In reply to Alex Granni from comment #8)
> (In reply to Alex Granni from comment #7)
> > (In reply to Eric Engestrom from comment #4)
> > > Hi Alex,
> > > Would you mind testing the work-in-progress branch and report if it works
> > > when building with Meson?
> > > git://people.freedesktop.org/~dbaker/mesa meson-windows
> > That branch appears to be incomplete. It has only 24 of the 48 patches in
> > the series:
> > https://cgit.freedesktop.org/~dbaker/mesa/log/?h=meson-windows
> > Full series: https://patchwork.freedesktop.org/series/44596/
> > After looking at the 46th patch in the series that acts like a blueprint I
> > noticed the branch is incomplete.
> Dylan posted the Meson windows branch on Freedesktop Gitlab. I'll test this
> issue with Meson soon.

Tested and it builds successfully, so it's a Scons only issue. Because Meson has GLES enabled by default unlike Scons it is not much of a surprise it's unaffected.

This got fixed by having offending feature removed.