pitrou commented on code in PR #46216: URL: https://github.com/apache/arrow/pull/46216#discussion_r2056281632
########## cpp/subprojects/README.md: ########## @@ -0,0 +1,64 @@ +# Meson Subprojects Review Comment: I think you need to add a license header above. ########## cpp/subprojects/README.md: ########## @@ -0,0 +1,64 @@ +# Meson Subprojects + +The contents of this directory are exclusively used by the Meson build configuration to +manage project dependencies. The Meson documentation for this functionality can be found +at https://mesonbuild.com/Subprojects.html + +To summarize, Arrow relies upon other projects to successfully compile and link. In +the case that those dependencies cannot be found on the host system, Meson by convention +forces users to place those dependencies in the ``subprojects`` directory at the root +of the project. + +The easiest way to populate subprojects is to use Meson's +[WrapDB system](https://mesonbuild.com/Wrapdb-projects.html). To illustrate how this +works, let's take a look at the ``googletest`` library that Arrow depends upon for Review Comment: If this is a markdown file, you need to use markdown markup not reST :) Therefore only single backticks ```suggestion works, let's take a look at the `googletest` library that Arrow depends upon for ``` ########## cpp/subprojects/README.md: ########## @@ -0,0 +1,64 @@ +# Meson Subprojects + +The contents of this directory are exclusively used by the Meson build configuration to +manage project dependencies. The Meson documentation for this functionality can be found +at https://mesonbuild.com/Subprojects.html + +To summarize, Arrow relies upon other projects to successfully compile and link. In +the case that those dependencies cannot be found on the host system, Meson by convention +forces users to place those dependencies in the ``subprojects`` directory at the root +of the project. + +The easiest way to populate subprojects is to use Meson's +[WrapDB system](https://mesonbuild.com/Wrapdb-projects.html). To illustrate how this +works, let's take a look at the ``googletest`` library that Arrow depends upon for +its test system. To create that as a subproject, a developer once ran: + +```bash +meson wrap install gtest +``` + +From the project root directory. From that invocation, Meson creates the +``subprojects/gtest.wrap`` file which instructs the build system where it can +get the source for gtest (if required), optionally alongside any "patch files" +required to build gtest. Note that patch files are optional; if a project uses +Meson natively, there is no need for patch files. However, if the project uses +another build system (in the case of gtest, Bazel or CMake), then the patch files +are user-created Meson configuration files that still expose the required +build targets, without being a full rewrite of the native build generator. For +an example of a user-created patch file for googletest, check out +https://github.com/mesonbuild/wrapdb/tree/9e3862083a250680061aa46e8746499c419ad43c/subprojects/packagefiles/gtest + +If you depend upon a project that is not available in Meson's WrapDB system, +you may still be able to have Meson auto-generate a wrapper for it. An example +of this is the ``subprojects/azure.wrap``, which looks like: + +``` +[wrap-file] +source_url = https://github.com/Azure/azure-sdk-for-cpp/archive/azure-identity_1.9.0.tar.gz +source_filename = azure-sdk-for-cpp-azure-identity_1.9.0.tar.gz +source_hash = 97065bfc971ac8df450853ce805f820f52b59457bd7556510186a1569502e4a1 +directory = azure-sdk-for-cpp-azure-identity_1.9.0 +method = cmake +``` + +The ``method = cmake`` line is important here; it instructs Meson to inspect any +CMakeLists.txt files from the downloaded source and auto generate Meson configuration +files therefrom. The generated meson.build configuration(s) will be placed in +<build_directory>/subprojects/<subproject_name> at project configuration time. Review Comment: ```suggestion `<build_directory>/subprojects/<subproject_name>` at project configuration time. ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@arrow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
