How to build zstd as a subproject with meson build system

I want to use zstd compression library for my C++ library project. My build system is based on meson. My meson.build file looks like this

project('foo', 'cpp', default_options : 
    ['cpp_std=c++17', 'buildtype=release'], 
    version : '0.1', license: 'MIT')

subproject('zstd', default_options: 'builddir=build/meson')

I made a zstd meson wrap file subprojects/zstd.wrap

[wrap-file]
directory = zstd-1.4.5

source_url = https://github.com/facebook/zstd/releases/download/v1.4.5/zstd-1.4.5.tar.gz
source_filename = zstd-1.4.5.tar.gz
source_hash = 98e91c7c6bf162bf90e4e70fdbc41a8188b9fa8de5ad840c401198014406ce9e

When I run meson compile I get this error

../meson.build:5:0: ERROR: Subproject exists but has no meson.build file

The issue seems to be in the fact that zstd uses CMAKE as a default build system and meson file lives in build/meson subfolder, and not in the root where meson expects it. I tried:

• Using default_options: 'builddir=build/meson' for the subproject, but that had no effect
• Building zstd using CMAKE integration but failed with other errors and it made the setup more complicated
• Making a patch to move zstd meson build files up two directories to the root of zstd, but that required more dependencies and later failed with paths resolution, as zstd expects files in build/meson and not in the root.

Can I easily build zstd as a meson subproject for my C++ library?

There is no option builddir in meson, and with default_options you can anyway set only that subproject's project options (zstd/build/meson/meson_options.txt). Thus, I think, the only way to solve this is to create a patch and it should be rather simple:

1. create meson.build in root subprojects' dir

2. move project(...) from zstd/build/meson/meson.build to this one

3. add subdir, so it contains:

   project(...)

   subdir('build')

4. drop one-line meson.build to zstd/build

   subdir('meson')