RE: [PATCH] meson: update doc logic for Windows

["Varghese, Vipin" <Vipin.Varghese@amd.com>]

[AMD Official Use Only]

<snipp>
>
> 26/03/2022 03:59, Vipin Varghese:
> > Support for shell scripts doxy-html-custom, generate_doxygen and 
> > generate_examples are absent. The current patch address the same by 
> > disabling document build notifying the user.
>
> It should not prevent generating guides with sphinx.
>
> We did get error from `doc/meson` stating ` echo command not available 
> on windows` for both cmd and powershell for the line ``` 
> run_target('doc', command: [echo, message, doc_target_names],
>     depends: doc_targets)
> ```

This line never searches for "echo" command, e8c90926bdde ("doc: fix build on Windows with Meson 0.58") introduced "echo" variable precisely to avoid this.
Can you give the full log?

Hi Dmitry, as requested please find the logs attached below for windows native build for DPDK

Modified `doc/meson.build` to highlight the docs build echo log as

```
if doc_targets.length() == 0
    message = 'No docs targets found'
else
    message = 'Building docs:'
endif

message('=========================================\n\n\n\n\n\n')

run_target('doc', command: [echo, message, doc_target_names],
    depends: doc_targets)

message('=========================================\n\n\n\n\n\n')
```

Meson Logs:
```
The Meson build system
Version: 0.61.3
<snipp>

Program doxygen found: YES (C:\Program Files\doxygen\bin\doxygen.EXE)
Program generate_doxygen.sh found: YES (sh -e C:\Users\Administrator\Desktop\dpdk\doc\api\generate_doxygen.sh)
Program generate_examples.sh found: YES (sh -e C:\Users\Administrator\Desktop\dpdk\doc\api\generate_examples.sh)
Program doxy-html-custom.sh found: YES (sh -e C:\Users\Administrator\Desktop\dpdk\doc\api\doxy-html-custom.sh)
Configuring doxy-api.conf using configuration
Program sphinx-build found: YES (C:\Users\Administrator\AppData\Local\Programs\Python\Python310\Scripts\sphinx-build.EXE)

```

Actual log from `meson build` (there is no echo message stating No docs targets found or Building docs:)
```
Message: =========================================






Message: =========================================
```

Ninja build error log
```
Found ninja-1.10.2 at "C:\Program Files\Meson\ninja.EXE"
Cleaning... 0 files.
[1/2] Generating doc/api/examples.dox with a custom command
FAILED: doc/api/examples.dox
"sh" "-e" "C:/Users/Administrator/Desktop/dpdk/doc/api/generate_examples.sh" "C:/Users/Administrator/Desktop/dpdk/examples" "doc/api/examples.dox"
CreateProcess failed: The system cannot find the file specified.
ninja: build stopped: subcommand failed.

C:\Users\Administrator\Desktop\dpdk>
```


<snipp>

> I suppose we could replace shell scripts with Python equivalent.
>
> I am trying to minimize the changes as first step: fix the build error by disabling on windows`.
> Next step we can convert to python to make it cross platform independent.

If something is explicitly requested but not supported, there should be a failure.
By the way, -Denable_docs=true works when cross-compiling for Windows, so disabling docs for this target is not right.
I think we should sort out what's causing an issue with "echo" for you (it shouldn't happen), then fix the scripts to fully enable docs.

Are you recommending

Windows libraries and binaries should be cross build from linux (where all dependencies and shell script works)?

Or

let us enhance the check for windows native build, if yes for option `-Denable_docs=true, we can stop the build for docs`.

If the latter is suggestion, I will share v2 patch to check the same.