x.py test (i.e. compiletest etc) should pass `--diagnostic-width`

[pnkfelix]

Proposal

x.py test (i.e. compiletest etc) should pass --diagnostic-width to avoid a dependency on the reported terminal width

Right now, odd environments may have a seemingly absurdly small terminal width, and this can currently cause our tests to break.

See discussion in https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/rustc_expand.20test.20failures.20on.20nightly/near/378563184

Mentors or Reviewers

• pnkfelix can mentor or outright implement this.

Process

The main points of the Major Change Process are as follows:

• File an issue describing the proposal.
• A compiler team member or contributor who is knowledgeable in the area can second by writing @rustbot second.
  • Finding a "second" suffices for internal changes. If however, you are proposing a new public-facing feature, such as a -C flag, then full team check-off is required.
  • Compiler team members can initiate a check-off via @rfcbot fcp merge on either the MCP or the PR.
• Once an MCP is seconded, the Final Comment Period begins. If no objections are raised after 10 days, the MCP is considered approved.

You can read more about Major Change Proposals on forge.

Comments

This issue is not meant to be used for technical discussion. There is a Zulip stream for that. Use this issue to leave procedural comments, such as volunteering to review, indicating that you second the proposal (or third, etc), or raising a concern that you would like to be addressed.

[rustbot]

This issue is not meant to be used for technical discussion. There is a Zulip stream for that. Use this issue to leave procedural comments, such as volunteering to review, indicating that you second the proposal (or third, etc), or raising a concern that you would like to be addressed.

cc @rust-lang/compiler @rust-lang/compiler-contributors

[davidtwco]

@rustbot second

[pnkfelix]

@ehuss reports that PR rust-lang/rust#113942 should fix all the cases where I encountered an issue here (basically, the tools are already taking pains to remove the contextual dependence here, and the rustc_expand tests were a special case that had to be addressed in a different manner).

Closing MCP as not relevant.