Wrapper_c - Yet Another Clang's JSON Compilation Database Generator

WRAPPER_C is a compiler wrapper. It is another Clang’s JSON compilation database generator for make-based build systems.

Unlike Bear which uses LD_PRELOAD, wrapper_c exploits the implicit variables CC and CXX to intercept the compilation commands from make and forwards the commands to the compiler.

In this post, I will show how to use wrapper_c to generate compile_commands.json for PostgreSQL.

I use docker to set the enviroment up. The followings are steps.

Create a file named Dockerfile and edit it using the following content.

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FROM ubuntu:22.04

RUN apt-get update && apt-get --yes upgrade

RUN apt-get install --yes build-essential python-is-python3 git python3-pip libreadline-dev bison flex

RUN pip install meson ninja

# Install wrapper_c.
RUN git clone https://github.com/adonis0147/wrapper_c && \
    cd /wrapper_c && \
    git submodule update --init --progress && \
    meson build --buildtype=release -Dprefix=/opt/wrapper_c && \
    ninja install -C build

CMD ["/bin/bash"]

Build the docker image.

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docker build --platform=linux/x86_64 -t wrapper_c .

Run the image.

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mkdir -p data
docker run -it --mount type=bind,source="$(pwd)/data",target=/data wrapper_c bash

Run the following commands to finish the preparation.

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# Download the source code of PostgreSQL.
cd /data
git clone https://github.com/postgres/postgres
cd postgres
mkdir build
cd build

The usage of wrapper_c is simple. Just run the following commands and compile_commands.json will be generated.

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CC=/opt/wrapper_c/bin/wrapper_gcc \
CXX=/opt/wrapper_c/bin/wrapper_g++ \
../configure --prefix="$(pwd)/output" --enable-debug --enable-cassert

/opt/wrapper_c/bin/wrapper_make -j "$(nproc)"

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