doc-test: In Markdown tests, Use all of <h1> to <h6> as the test name

[kennytm]

This mainly simplifies debugging error index tests, as the error codes are <h2>s in the huge document containing all codes.

[rust-highfive]

r? @frewsxcv

(rust_highfive has picked a reviewer for you, use r? to override)

[kennytm]

The rationale is to avoid useless CI output like #44480 (comment).

The errors now look like:

...

---- $DIR/test/error-index.md - Rust_Compiler_Error_Index::E0626 (line 11733) stdout ----
	error[E0514]: found crate `std` compiled by an incompatible version of rustc
  |
  = help: please recompile that crate using this compiler (rustc 1.22.0-dev)
  = note: crate `std` path #1: $DIR/stage0-sysroot/lib/rustlib/x86_64-apple-darwin/lib/libstd_unicode-0dc809f4018b643d.rlib compiled by "rustc 1.21.0-beta.1 (198109911 2017-08-29)"
  = note: crate `std` path #2: $DIR/stage0-sysroot/lib/rustlib/x86_64-apple-darwin/lib/libstd-202599072911ceaa.rlib compiled by "rustc 1.21.0-beta.1 (198109911 2017-08-29)"
  = note: crate `std` path #3: $DIR/stage0-sysroot/lib/rustlib/x86_64-apple-darwin/lib/libstd-202599072911ceaa.dylib compiled by "rustc 1.21.0-beta.1 (198109911 2017-08-29)"

error: aborting due to previous error

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:525:8
thread 'rustc' panicked at 'couldn't compile the test', src/librustdoc/test.rs:281:12


failures:
    $DIR/test/error-index.md - Rust_Compiler_Error_Index::E0001::_::Note__this_error_code_is_no_longer_emitted_by_the_compiler_ (line 15)
    $DIR/test/error-index.md - Rust_Compiler_Error_Index::E0002::_::Note__this_error_code_is_no_longer_emitted_by_the_compiler_ (line 42)
    $DIR/test/error-index.md - Rust_Compiler_Error_Index::E0003::_::Note__this_error_code_is_no_longer_emitted_by_the_compiler_ (line 86)
    $DIR/test/error-index.md - Rust_Compiler_Error_Index::E0004 (line 103)
    $DIR/test/error-index.md - Rust_Compiler_Error_Index::E0004 (line 123)
    $DIR/test/error-index.md - Rust_Compiler_Error_Index::E0005 (line 150)
    $DIR/test/error-index.md - Rust_Compiler_Error_Index::E0005 (line 160)

...

I've conflated the current_header field into the names field since they now serve the same purpose. Also I've removed the cnt field since it is not read anywhere.

[GuillaumeGomez]

It's a bit ugly from my point of view. :-/

[kennytm]

What if we truncate to <h2>?

[carols10cents]

review reminder ping @GuillaumeGomez @QuietMisdreavus !

[QuietMisdreavus]

Okay yeah, i'm a little out of my depth as to what's exactly going on here, i'm going to let imperio take over.

r? @GuillaumeGomez

[GuillaumeGomez]

I appreciate the fact that you removed the cnt but I have difficulties to understand the rest. Can you provide a bit more explanations (and a comparison of the current output vs the new one) please?

[kennytm]

@GuillaumeGomez Added comments to explain the changed role of self.names and the action in register_header().

The "after" is shown in #44867 (comment). The "before" is like:

...

---- $DIR/test/error-index.md - Rust_Compiler_Error_Index (line 11733) stdout ----
	error[E0514]: found crate `std` compiled by an incompatible version of rustc
  |
  = help: please recompile that crate using this compiler (rustc 1.22.0-dev)
  = note: crate `std` path #1: $DIR/stage0-sysroot/lib/rustlib/x86_64-apple-darwin/lib/libstd_unicode-0dc809f4018b643d.rlib compiled by "rustc 1.21.0-beta.1 (198109911 2017-08-29)"
  = note: crate `std` path #2: $DIR/stage0-sysroot/lib/rustlib/x86_64-apple-darwin/lib/libstd-202599072911ceaa.rlib compiled by "rustc 1.21.0-beta.1 (198109911 2017-08-29)"
  = note: crate `std` path #3: $DIR/stage0-sysroot/lib/rustlib/x86_64-apple-darwin/lib/libstd-202599072911ceaa.dylib compiled by "rustc 1.21.0-beta.1 (198109911 2017-08-29)"

error: aborting due to previous error

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:525:8
thread 'rustc' panicked at 'couldn't compile the test', src/librustdoc/test.rs:281:12


failures:
    $DIR/test/error-index.md - Rust_Compiler_Error_Index (line 15)
    $DIR/test/error-index.md - Rust_Compiler_Error_Index (line 42)
    $DIR/test/error-index.md - Rust_Compiler_Error_Index (line 86)
    $DIR/test/error-index.md - Rust_Compiler_Error_Index (line 103)
    $DIR/test/error-index.md - Rust_Compiler_Error_Index (line 123)
    $DIR/test/error-index.md - Rust_Compiler_Error_Index (line 150)
    $DIR/test/error-index.md - Rust_Compiler_Error_Index (line 160)

...

[aidanhs]

Hi @GuillaumeGomez, have you had a chance to take another look at this?

[GuillaumeGomez]

Forgot, sorry. And I still don't like it much. But if other people are interested, then it should get merged. Well anyway, please pick another reviewer, the technical side looks fine to me but I don't like the new output much. :-/

[kennytm]

so... r? @alexcrichton ?

@GuillaumeGomez or do you have suggestions that makes the output looks nice while ensuring the markdown tests still show the <h2> in the test name?

[GuillaumeGomez]

No I don't, that's why I'd like someone else review this in case they have a better idea.

[alexcrichton]

@bors: r+

Looks great, thanks @kennytm!

[bors]

📌 Commit 0cdf587 has been approved by alexcrichton

[bors]

⌛ Testing commit 0cdf587 with merge a457e29...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: alexcrichton
Pushing a457e29 to master...