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NAME

bazel-compile-commands - generate a compile_commands.json file from a Bazel workspace

SYNOPSIS

bazel-compile-commands [-h]

bazel-compile-commands [-av] [-b BAZEL-OPTION] [-B BAZEL-COMMAND] [-c COMPILER] [-o OUTPUT-FILE] [-s BAZEL-STARTUP-OPTION] [TARGETS]

DESCRIPTION

A non-intrusive way to generate a compile_commands.json file from a Bazel workspace. This is basically the CMAKE_EXPORT_COMPILE_COMMANDS option from CMake for Bazel.

This works by issuing a bazel aquery and parsing this output and converting into the compile commands JSON format.

When bazel-compile-commands is called it searches for a .bazelccrc file in the current directory or any parent directory. This file can be used to set default values for the arguments. The provided arguments via command line and from the configuration file are combined when bazel-compile-commands is called

OPTIONS

-a, --arguments

: Also write the array of arguments for each entry in the compile_commands.json file.

-B, --bazel-command BAZEL

: Path to the bazel executable. Default value is bazel. Can be set to bazelisk to use bazelisk instead of bazel.

-b, --bazelopt OPTION

: OPTION will be forwarded to Bazel when querying Bazel for build actions.

--config NAME

: Same as --bazelopt "--config=CONFIG". A config option from .bazelrc to apply when querying Bazel for build actions.

-c, --compiler FILE

: Replace the internal Bazel compiler wrapper script with this compiler (useful for macOS).

-h, --help

: Show the available options and exit.

-o, --output FILE

: Output file path of the compile_commands.json file. The default value is %workspace%/compile_commands.json the %workspace% part will be replaced with the actual worspace path which will be the output of bazel info workspace.

-R, --replace KEY=VALUE

: Replace occurrences of KEY with VALUE in the command and arguments field of each compile commands entry. Can be used to remove

--resolve

: Resolve symbolic links from the execroot/ directory (used by Bazel as sandbox environment) to the absolute path. Only links of file which point into the %workspace% will be resolved.

-s, --bazelsupopt OPTION

: Additional Bazel startup options to be added to the bazel call.

-v, --verbose

: Be more verbose and print additional informations.

-w, --write

: Write the current supplied arguments into a .bazelccrc file such that further calls to bazel-compile-commands without arguments behaves the same as if the arguments are provided.

If a .bazelccrc file aready exists this file will be updated. When no such file exists, a new file in the current Bazel workspace will be created.

TARGETS

: All remaining arguments are expected to be Bazel targets for which the compile commands shall be generated. The default is //... to generate the compile commands for all C/C++ files.

FILES

bazel-compile-commands will search for a .bazelccrc file in the current directory or any parent directory. If such a file is found this values are used and combined with the values from the command line.

An example .bazelccrc will look like:

verbose = 0
arguments = 0
bazel-command = bazel
output = %workspace%/compile_commands.json
targets = //...

EXAMPLES

REMOVE UNWANTED ARGUMENTS

We can remove arguments from the resulting command and arguments entries of each compile commands entry like so:

bazel-compile-commands --replace=-fno-canonical-system-headers= //...

With this, any occournce of -fno-canonical-system-headers will be removed (a flag which is understood by gcc but not by clang (including clangd and clang-tidy).

Compile multiple different bazel-compile-commands outputs

For uses cases like #46 where different Bazel targets require different build configurations one can use jq to combine multiple bazel-compile-commands outputs into one single commpile_commands.json file:

jq -s '[ .[0] + .[1] | group_by(.output)[] | add ]' \
  <(bazel-compile-commands -o - --config=configA //system-a//...) \
  <(bazel-compile-commands -o - --config=configB //system-b//...) \
  > compile_commands.json

We group by the output attribute, since this should be unique per compile_commands.json file (note: it is allowed when the same input file produces multiple district output files).

More information about jq can be found at: https://jqlang.github.io/jq/manual/