|author||David 'Digit' Turner <email@example.com>||Fri Nov 20 12:45:00 2020 +0100|
|committer||Commit Bot <firstname.lastname@example.org>||Fri Nov 20 20:55:36 2020 +0000|
[rust] Fix command arguments for non-rust native dependencies. The ninja Rust binary target writer did the following to generate the command arguments set to 'rustc' for non-rust native library dependencies (e.g. any native object file or shared library): 1- Collect the ordered set of each dependency's directory, then write it as a series of `-Lnative=<dir>` arguments. 2- For any dependency whose name begins with 'lib', write it as `-l<name>`, where <name> is the dependency's file name without a "lib" prefix and without a file extension. 2- For non-"lib" dependencies, just use `-Clink-arg=<path>` instead. However, while working on the Fuchsia build system, I found that rules 1 and 2 are both problematic: - Rule 1 means there is a possibility of linking the wrong library in the final binary. E.g. consider a dependency list like: dir1/libfoo.so dir2/libbar.so This gets translated into: -Lnative=dir1 -Lnative=dir2 -lfoo -lbar And if dir1/libbar.so happens to exist, it will be wrongly selected by the linker. - Rule 2 assumes the file extension is something like ".so", ".dylib" or ".a" , i.e. something the linker will look for automatically, however, in the Fuchsia build, we have to link against files named "libc.so.debug" and "libzircon.so.debug" (where the ".debug" prefix means these are the unstripped versions of the libraries). This ends up translated into: -Lnative=<dir2> -Lnative=<dir1> -lc.so -lzircon.so And the linker will look for libc.so.so and libzircon.so.so instead of the real files (and of course print an error message). Our current work-around is to create link scripts with this name that redirect to the real file, but this is ugly. This CL simply fixes the issue by using `-Clink-arg=<path>` in all cases. The `-Lnative=<dir>` arguments are still required to make `#[link(...)]` directives work correctly. Bug: 217 Change-Id: I5f7210300eea0effe3ed99b4f6aff5f07fb05518 Reviewed-on: https://gn-review.googlesource.com/c/gn/+/10721 Commit-Queue: David Turner <email@example.com> Reviewed-by: Petr Hosek <firstname.lastname@example.org> Reviewed-by: Brett Wilson <email@example.com>
GN is a meta-build system that generates build files for Ninja.
Alternatively, you can build GN from source:
git clone https://gn.googlesource.com/gn cd gn python build/gen.py ninja -C out # To run tests: out/gn_unittests
On Windows, it is expected that
lib.exe can be found in
PATH, so you'll want to run from a Visual Studio command prompt, or similar.
On Linux and Mac, the default compiler is
clang++, a recent version is expected to be found in
PATH. This can be overridden by setting
There is a simple example in examples/simple_build directory that is a good place to get started with the minimal configuration.
To build and run the simple example with the default gcc compiler:
cd examples/simple_build ../../out/gn gen -C out ninja -C out ./out/hello
For a maximal configuration see the Chromium setup:
and the Fuchsia setup:
If you find a bug, you can see if it is known or report it in the bug database.
GN uses Gerrit for code review. The short version of how to patch is:
Register at https://gn-review.googlesource.com. ... edit code ... ninja -C out && out/gn_unittests
Then, to upload a change for review:
git commit git push origin HEAD:refs/for/master
The first time you do this you'll get an error from the server about a missing change-ID. Follow the directions in the error message to install the change-ID hook and run
git commit --amend to apply the hook to the current commit.
When revising a change, use:
git commit --amend git push origin HEAD:refs/for/master
which will add the new changes to the existing code review, rather than creating a new one.
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You may ask questions and follow along with GN‘s development on Chromium’s gn-dev@ Google Group.