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Emit compile_commands.json #497

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thedataking opened this issue May 13, 2020 · 6 comments · May be fixed by #682
Open

Emit compile_commands.json #497

thedataking opened this issue May 13, 2020 · 6 comments · May be fixed by #682

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@thedataking
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Many editors and IDEs work better on C code when provided with a compilation database (compile_commands.json) because it tells the editor where to look for include files, the values of defines, etc.. Here are tools to generate compilation databases when using Make or cmake to build a C code base. For projects where the C code is embedded a Rust project and built with this crate, it would be helpful to be able to get a compilation database.

@alexeyr
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alexeyr commented Nov 16, 2020

I was thinking and the problem is, what happens with multiple Builds? They need to combine their commands into a single JSON array, so just appending to a file doesn't work.

Option 1: be explicit. Create a CompilationDatabase, pass it to each Build, emit with a method on CompilationDatabase. Maybe on Drop as well to deal with panicking commands?
Option 2: Create a static CompilationDatabase, each Build (optionally) adds itself to it, on Drop removes itself. When all are removed, the database is written.
Option 3: before executing every new command read the current compilation database from the file, parse it, add the new command entry and write back.

All options have something to dislike, I am not sure which is better. Or maybe there is an option 4.

@schrieveslaach
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@alexeyr, what do you think about following option:

let mut database = CompilationDatabase::new();

cc::Build::new().file("blobstore.c").compile_and_store("blobstore", &mut database);
// … more builds

database.store(/* maybe with a path */);

If we find a nice API I'm happy to contribute that API.

schrieveslaach added a commit to schrieveslaach/cc-rs that referenced this issue May 26, 2022
This commit adds API to record the compilation invocations in order to
emit compile_commands.json a.k.a. JSON compilation database.

Fixes rust-lang#497
@schrieveslaach schrieveslaach linked a pull request May 26, 2022 that will close this issue
schrieveslaach added a commit to schrieveslaach/cc-rs that referenced this issue May 26, 2022
This commit adds API to record the compilation invocations in order to
emit compile_commands.json a.k.a. JSON compilation database.

Fixes rust-lang#497
schrieveslaach added a commit to schrieveslaach/cc-rs that referenced this issue Jul 4, 2022
This commit adds API to record the compilation invocations in order to
emit compile_commands.json a.k.a. JSON compilation database.

Fixes rust-lang#497
schrieveslaach added a commit to schrieveslaach/cc-rs that referenced this issue Jul 4, 2022
This commit adds API to record the compilation invocations in order to
emit compile_commands.json a.k.a. JSON compilation database.

Fixes rust-lang#497
schrieveslaach added a commit to schrieveslaach/cc-rs that referenced this issue Jul 7, 2022
This commit adds API to record the compilation invocations in order to
emit compile_commands.json a.k.a. JSON compilation database.

Fixes rust-lang#497
schrieveslaach added a commit to schrieveslaach/cc-rs that referenced this issue Jul 7, 2022
This commit adds API to record the compilation invocations in order to
emit compile_commands.json a.k.a. JSON compilation database.

Fixes rust-lang#497
schrieveslaach added a commit to schrieveslaach/cc-rs that referenced this issue Jul 7, 2022
This commit adds API to record the compilation invocations in order to
emit compile_commands.json a.k.a. JSON compilation database.

Fixes rust-lang#497
schrieveslaach added a commit to schrieveslaach/cc-rs that referenced this issue Jul 23, 2022
This commit adds API to record the compilation invocations in order to
emit compile_commands.json a.k.a. JSON compilation database.

Fixes rust-lang#497
schrieveslaach added a commit to schrieveslaach/cc-rs that referenced this issue Jul 23, 2022
This commit adds API to record the compilation invocations in order to
emit compile_commands.json a.k.a. JSON compilation database.

Fixes rust-lang#497
schrieveslaach added a commit to schrieveslaach/cc-rs that referenced this issue Jul 23, 2022
This commit adds API to record the compilation invocations in order to
emit compile_commands.json a.k.a. JSON compilation database.

Fixes rust-lang#497
schrieveslaach added a commit to schrieveslaach/cc-rs that referenced this issue Jul 23, 2022
This commit adds API to record the compilation invocations in order to
emit compile_commands.json a.k.a. JSON compilation database.

Fixes rust-lang#497
@vext01
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vext01 commented Mar 16, 2023

Came here to request this very same feature!

In the meantime I think I may be able to capture the compiler commands by wrapping the compiler with a shell script...

@sporksmith
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In the meantime I think I may be able to capture the compiler commands by wrapping the compiler with a shell script...

That was ultimately our solution in shadow, which is in the process of incrementally migrating from C to Rust. We already had a setup script to wrap our build process, so we changed it to use the bear wrapper to generate compile_commands.json.

@jeteve
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jeteve commented Jun 21, 2024

@sporksmith Could you point to how you setup the bear wrapper for cc::Build?

@sporksmith
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@sporksmith Could you point to how you setup the bear wrapper for cc::Build?

https://github.com/shadow/shadow/blob/main/setup#L249

Our build system has accumulated a number of layers. We use a custom python script setup, which invokes cmake, which generates makefiles, which have both pure C targets and Rust targets, some of which have their own build scripts that compile C code.

Instead of running just make to build everything from the top-level generated makefiles, we run bear --append -- make, which adds an LD_PRELOAD to the environment before invoking make, which in turn intercepts and records compiler commands.

For a project that doesn't have the cmake layer, I think you could run bear --append -- cargo build.

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6 participants