bazelrc line with missing command should fail fast instead of silently ignoring

[alexeagle]

Description of the bug:

It's very easy to forget the command in a bazelrc file, for example this mistake in
https://github.com/aspect-build/rules_js/pull/34/files
--host_jvm_args=-DBAZEL_TRACK_SOURCE_DIRECTORIES=1 simply has no effect because it's missing a command before the flags appear on that line, the correct way is

startup --host_jvm_args=-DBAZEL_TRACK_SOURCE_DIRECTORIES=1

This silent failure is confusing to users, and a source of bugs. I've seen many cases at clients where lines in the bazelrc are being silently ignored.

What's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

No response

Which operating system are you running Bazel on?

No response

What is the output of bazel info release?

No response

If bazel info release returns development version or (@non-git), tell us how you built Bazel.

No response

What's the output of git remote get-url origin; git rev-parse master; git rev-parse HEAD ?

No response

Have you found anything relevant by searching the web?

No response

Any other information, logs, or outputs that you want to share?

No response

[brandjon]

Not familiar with the code off-hand, but it's possible the rc file has parsers in both Java and C++ (in order for the client to interpret startup flags).

[haxorz]

This is the same as internal issue 69956078 (Nov 2017).

See my comment 6 there (Dec 2022) for an internal-only thing we'd need to do if we want to do a good job addressing this issue.

[layus]

Hi,

I just got bitten by this one, and it hurts pretty bad given I knew I added the flags, I just missed that damn "build" in front of them.

I see there are some internal blockers. Anything we can do to help move it forward, or work around internal code inside open Bazel ? What is the status of this internal issue ?

For reference: https://bazelbuild.slack.com/archives/CA31HN1T3/p1704752021290139

[haxorz]

There's some Google-internal code that separately implements the .blazerc parsing logic. It was a port of the C++ code used in the Bazel client codebase (the code in question for this GitHub issue here). We want this code and that code to have the same behavior. So the blocker would be that whoever imports the PR for this GitHub issue here also needs to port the change to that code.

One way to help move this GitHub issue forward would be to mail a PR that fixes the bug. That would spur someone to review it (and then have to do the additional work mentioned above).

[layus]

So, I have #20895 addressing this issue. It is a bit bold, but anything more involved requires the client to know the list of valid commands, which introduces redundancy. I would love to get feedback from people involved here.

[keith]

For reference here are some more edge cases I found:

build --copt=-v \
  # some comment \
  --copt=-invalid

build --copt=-v \