Ok, I am trying to meson and is struggling with meson.build file. I looked up the examples page: https://github.com/mesonbuild/meson/tree/master/test%20cases/d which has a lot of examples but not the one that shows you how to build your project with some external dependency :)

Let's say we have a simple dir "myproj" with "meson.build" in it and some source files like "app.d" and "helper_functions.d".

~/myproj
   app.d
   helper_functions.d
   meson.build

"helper_functions.d" uses let's say lubeck library which according to https://forum.dlang.org/thread/nghoprwkihazjikyhshz@forum.dlang.org is supported by meson.

Here is my meson.build:
-----------------------
project('demo', 'd',
  version : '0.1',
  default_options : ['warning_level=3']
  )

lubeck = dependency('lubeck', version: '>=1.1.7')
ed = executable('mir_quickstart', 'app.d', dependencies: lubeck, install : true)


However, when I try to build it I get the following error:
-----
$ meson build
The Meson build system
Version: 0.52.1
Source dir: /home/user/dev/github/demo
Build dir: /home/user/dev/github/demo/build
Build type: native build
Project name: demo
Project version: 0.1
D compiler for the host machine: ldc2 (llvm 1.18.0 "LDC - the LLVM D compiler (1.18.0):")
D linker for the host machine: GNU ld.gold 2.33.1
Host machine cpu family: x86_64
Host machine cpu: x86_64
Found pkg-config: /usr/bin/pkg-config (1.6.3)
Found CMake: /usr/bin/cmake (3.16.2)
Run-time dependency lubeck found: NO (tried pkgconfig and cmake)

meson.build:8:0: ERROR: Dependency "lubeck" not found, tried pkgconfig and cmake

A full log can be found at /home/user/dev/github/demo/build/meson-l
-----

What do I need to do in order to build the project with "lubeck" dependency in meson?

On Sunday, 12 January 2020 at 22:00:33 UTC, p.shkadzko wrote:
> What do I need to do in order to build the project with "lubeck" dependency in meson?

In difference to dub, meson will _not_ auto-download required software for you. You have to ways to go forward with this:

1 (IMHO the better way, especially if you ever want a distro to package your thing):

Install lubeck ala `git clone https://github.com/kaleidicassociates/lubeck && cd lubeck && meson build && ninja -C build install`. This will install lubeck to your system (by default into `/usr/local`, you can set a different by passing `--prefix` to meson). This will generate a so called pkg-config (`.pc`) file: https://github.com/kaleidicassociates/lubeck/blob/master/meson.build#L49 which meson will discover.

2 (The probably easier way in the short term):

Install lubeck via meson, then discover the dependency like specified here: https://mesonbuild.com/Dependencies.html#dependency-method

On Sunday, 12 January 2020 at 22:12:14 UTC, Rasmus Thomsen wrote:
> On Sunday, 12 January 2020 at 22:00:33 UTC, p.shkadzko wrote:
>> What do I need to do in order to build the project with "lubeck" dependency in meson?
>
> In difference to dub, meson will _not_ auto-download required software for you. You have to ways to go forward with this:
>
> 1 (IMHO the better way, especially if you ever want a distro to package your thing):
>
> Install lubeck ala `git clone https://github.com/kaleidicassociates/lubeck && cd lubeck && meson build && ninja -C build install`. This will install lubeck to your system (by default into `/usr/local`, you can set a different by passing `--prefix` to meson). This will generate a so called pkg-config (`.pc`) file: https://github.com/kaleidicassociates/lubeck/blob/master/meson.build#L49 which meson will discover.
>
> 2 (The probably easier way in the short term):
>
> Install lubeck via meson, then discover the dependency like specified here: https://mesonbuild.com/Dependencies.html#dependency-method

Why do you think 1 is the better way? I feel like it is a lot of manual work for just one dependency. Also, it is not a good idea to pollute your /usr/local with non-distro packages.

On Sunday, 12 January 2020 at 22:12:14 UTC, Rasmus Thomsen wrote:
> On Sunday, 12 January 2020 at 22:00:33 UTC, p.shkadzko wrote:
>> [...]
>
> In difference to dub, meson will _not_ auto-download required software for you. You have to ways to go forward with this:
>
> [...]

Thanks! I shall try it out.

On Sunday, 12 January 2020 at 22:20:16 UTC, p.shkadzko wrote:
> Why do you think 1 is the better way?

Well, I suppose I might be a bit biased being a distro packager, but not using dub ensures your package builds properly with what your distro uses (e.g. pkg-config). It _is_ more effort up front though, yes. Also, I feel like using a more standardized way of packaging via meson with pkg-config is better (and as a distro packager I would refrain from packaging something which uses a dub dependency instead of a (shared) pkg-config one).

> I feel like it is a lot of manual work for just one dependency. Also, it is not a good idea to pollute your /usr/local with non-distro packages.

Well, the only purpose of /usr/local is for you to put your non-distro stuff there, /usr is the package manager's territory :)

On Sunday, 12 January 2020 at 22:12:14 UTC, Rasmus Thomsen wrote:
> On Sunday, 12 January 2020 at 22:00:33 UTC, p.shkadzko wrote:
>> [...]
>
> In difference to dub, meson will _not_ auto-download required software for you. You have to ways to go forward with this:
>
> [...]

I followed the 1 step, namely git cloned the lubeck and installed it with meson into /usr/local however, I still get the same error. Could I miss anything?

On Monday, 13 January 2020 at 17:14:29 UTC, p.shkadzko wrote:
> On Sunday, 12 January 2020 at 22:12:14 UTC, Rasmus Thomsen wrote:
>> On Sunday, 12 January 2020 at 22:00:33 UTC, p.shkadzko wrote:
>>> [...]
>>
>> In difference to dub, meson will _not_ auto-download required software for you. You have to ways to go forward with this:
>>
>> [...]
>
> I followed the 1 step, namely git cloned the lubeck and installed it with meson into /usr/local however, I still get the same error. Could I miss anything?

I had to set PKG_CONFIG_PATH to "/usr/local/lib/pkgconfig". For some reason Manjaro distro doesn't have it set by default. After setting the pkgconfig path, lubeck is getting found and everything works.

On Monday, 13 January 2020 at 19:56:35 UTC, p.shkadzko wrote:
> On Monday, 13 January 2020 at 17:14:29 UTC, p.shkadzko wrote:
>> On Sunday, 12 January 2020 at 22:12:14 UTC, Rasmus Thomsen wrote:
>>> On Sunday, 12 January 2020 at 22:00:33 UTC, p.shkadzko wrote:
>>>> [...]
>>>
>>> In difference to dub, meson will _not_ auto-download required software for you. You have to ways to go forward with this:
>>>
>>> [...]
>>
>> I followed the 1 step, namely git cloned the lubeck and installed it with meson into /usr/local however, I still get the same error. Could I miss anything?
>
> I had to set PKG_CONFIG_PATH to "/usr/local/lib/pkgconfig". For some reason Manjaro distro doesn't have it set by default. After setting the pkgconfig path, lubeck is getting found and everything works.

After I ran "meson build" I got the following output:
-----------------------
The Meson build system
Version: 0.52.1
Source dir: /home/tastyminerals/dev/test_proj
Build dir: /home/tastyminerals/dev/test_proj/build
Build type: native build
Project name: mir_quickstart
Project version: 0.1
D compiler for the host machine: ldc2 (llvm 1.18.0 "LDC - the LLVM D compiler (1.18.0):")
D linker for the host machine: GNU ld.gold 2.33.1
Host machine cpu family: x86_64
Host machine cpu: x86_64
Found pkg-config: /usr/bin/pkg-config (1.6.3)
Run-time dependency mir-algorithm found: YES 3.4.0
Run-time dependency lubeck found: YES 1.0.0
Build targets in project: 1
Found ninja-1.9.0 at /usr/bin/ninja

I then cd to build/ dir and run "ninja"
------------------------
[2/2] Linking target test_proj.tart@exe/app.d.o'.

But when I try to run compiled app.d file as demo_run, I get:
------------------------
./demo_run: error while loading shared libraries: libmir-algorithm.so: cannot open shared object file: No such file or directory

I thought that if meson builds and finds the external libs successfully and ninja links everything, all should be fine. I don't understand. Why the compiled file cannot find the external library?

On Monday, 13 January 2020 at 20:53:43 UTC, p.shkadzko wrote:
> On Monday, 13 January 2020 at 19:56:35 UTC, p.shkadzko wrote:
>> On Monday, 13 January 2020 at 17:14:29 UTC, p.shkadzko wrote:
>>> [...]
>>
>> I had to set PKG_CONFIG_PATH to "/usr/local/lib/pkgconfig". For some reason Manjaro distro doesn't have it set by default. After setting the pkgconfig path, lubeck is getting found and everything works.
>
> After I ran "meson build" I got the following output:
> -----------------------
> The Meson build system
> Version: 0.52.1
> Source dir: /home/tastyminerals/dev/test_proj
> Build dir: /home/tastyminerals/dev/test_proj/build
> Build type: native build
> Project name: mir_quickstart
> Project version: 0.1
> D compiler for the host machine: ldc2 (llvm 1.18.0 "LDC - the LLVM D compiler (1.18.0):")
> D linker for the host machine: GNU ld.gold 2.33.1
> Host machine cpu family: x86_64
> Host machine cpu: x86_64
> Found pkg-config: /usr/bin/pkg-config (1.6.3)
> Run-time dependency mir-algorithm found: YES 3.4.0
> Run-time dependency lubeck found: YES 1.0.0
> Build targets in project: 1
> Found ninja-1.9.0 at /usr/bin/ninja
>
> I then cd to build/ dir and run "ninja"
> ------------------------
> [2/2] Linking target test_proj.tart@exe/app.d.o'.
>
> But when I try to run compiled app.d file as demo_run, I get:
> ------------------------
> ./demo_run: error while loading shared libraries: libmir-algorithm.so: cannot open shared object file: No such file or directory
>
> I thought that if meson builds and finds the external libs successfully and ninja links everything, all should be fine. I don't understand. Why the compiled file cannot find the external library?

$LD_LIBRARY_PATH was not set to "/usr/local/lib" where libmir-algorithm.so is located. I had to set it explicitly and recompile the project but then I get another error message:

./demo_proj: error while loading shared libraries: subprojects/mir-algorithm/libmir-algorithm.so.3.4.0: cannot open shared object file: No such file or directory


(ಠ_ಠ)

On Monday, 13 January 2020 at 21:15:51 UTC, p.shkadzko wrote:
> On Monday, 13 January 2020 at 20:53:43 UTC, p.shkadzko wrote:
>> On Monday, 13 January 2020 at 19:56:35 UTC, p.shkadzko wrote:
>>> On Monday, 13 January 2020 at 17:14:29 UTC, p.shkadzko wrote:
>>>> [...]
>>>
>>> I had to set PKG_CONFIG_PATH to "/usr/local/lib/pkgconfig". For some reason Manjaro distro doesn't have it set by default. After setting the pkgconfig path, lubeck is getting found and everything works.
>>
>> After I ran "meson build" I got the following output:
>> -----------------------
>> The Meson build system
>> Version: 0.52.1
>> Source dir: /home/tastyminerals/dev/test_proj
>> Build dir: /home/tastyminerals/dev/test_proj/build
>> Build type: native build
>> Project name: demo_proj
>> Project version: 0.1
>> D compiler for the host machine: ldc2 (llvm 1.18.0 "LDC - the LLVM D compiler (1.18.0):")
>> D linker for the host machine: GNU ld.gold 2.33.1
>> Host machine cpu family: x86_64
>> Host machine cpu: x86_64
>> Found pkg-config: /usr/bin/pkg-config (1.6.3)
>> Run-time dependency mir-algorithm found: YES 3.4.0
>> Run-time dependency lubeck found: YES 1.0.0
>> Build targets in project: 1
>> Found ninja-1.9.0 at /usr/bin/ninja
>>
>> I then cd to build/ dir and run "ninja"
>> ------------------------
>> [2/2] Linking target test_proj.tart@exe/app.d.o'.
>>
>> But when I try to run compiled app.d file as demo_run, I get:
>> ------------------------
>> ./demo_run: error while loading shared libraries: libmir-algorithm.so: cannot open shared object file: No such file or directory
>>
>> I thought that if meson builds and finds the external libs successfully and ninja links everything, all should be fine. I don't understand. Why the compiled file cannot find the external library?
>
> $LD_LIBRARY_PATH was not set to "/usr/local/lib" where libmir-algorithm.so is located. I had to set it explicitly and recompile the project but then I get another error message:
>
> ./demo_proj: error while loading shared libraries: subprojects/mir-algorithm/libmir-algorithm.so.3.4.0: cannot open shared object file: No such file or directory
>
>
> (ಠ_ಠ)

My test app.d didn't have any imports for mir.ndslice and lubeck. After I imported them, ninja threw the following error.
-----------
[1/2] Compiling D object 'demo_proj@exe/app.d.o'.
FAILED: demo_proj@exe/app.d.o
ldc2 -I=demo_proj@exe -I=. -I=.. -I/usr/local/include/d/lubeck -I/usr/local/include/d/mir-algorithm -I/usr/local/include/d/mir-core -I/usr/local/include/d/mir-blas -I/usr/local/include/d/mir-lapack -I/usr/local/include/d/mir-random -enable-color -wi -dw -g -d-debug -of='demo_proj@exe/app.d.o' -c ../app.d
/usr/local/include/d/lubeck/lubeck.d(8): Error: module cblas is in file 'cblas.d' which cannot be read
import path[0] = demo_proj@exe
import path[1] = .
import path[2] = ..
import path[3] = /usr/local/include/d/lubeck
import path[4] = /usr/local/include/d/mir-algorithm
import path[5] = /usr/local/include/d/mir-core
import path[6] = /usr/local/include/d/mir-blas
import path[7] = /usr/local/include/d/mir-lapack
import path[8] = /usr/local/include/d/mir-random
import path[9] = /usr/include/dlang/ldc
ninja: build stopped: subcommand failed.

cblas.d is located in /usr/local/include/d/cblas/cblas/cblas.d
I added /usr/local/include/d/cblas/cblas to $PATH but that didn't help :(