RFR: JDK-8218807: Compilation database (compile_commands.json) may contain obsolete items

[Magnus Ihse Bursie]

On 2019-02-12 09:01, Robin Westberg wrote:
> Hi all,
>
> When generating a compilation database by either "make compile-commands" or "make compile-commands-hotspot", every object file that should be built results in a temporary json fragment describing the compiler invocation. However, when the final compile_commands.json file is assembled, all these temporary files are combined, regardless of whether they belong to the current make invocation or were left behind from a previous one.
>
> This has the unfortunate effect that "make compile-commands" followed by "make compile-commands-hotspot" generates something very different from an initial invocation of "make compile-commands-hotspot". Also, if a source file has been removed, it will still retain an entry in the final compile_commands.json file until the build directory is cleaned. This will lead to errors if generating an IDE project from the compile_commands.json file.
>
> Proposed solution is to always remove all previous temporary json fragments and generate them again. This generation is quite fast and only adds a second or two for repeated invocations of "make compile-commands”, which should be a reasonable tradeoff for ensuring that the compilation database contains correct information.
>
> Issue: https://bugs.openjdk.java.net/browse/JDK-8218807
> Webrev: http://cr.openjdk.java.net/~rwestberg/8218807/
Looks good to me.

/Magnus
> Testing: make test-make-compile-commands, build windows, linux, mac, solaris
>
> Best regards,
> Robin