Remove BadImplStripper code

[GuillaumeGomez]

Following this comment suggestion. I gave a try at removing BadImplStripper.

I ran rustdoc tests and all passed so apparently it's now possible to not rely on BadImplStripper anymore. Is there maybe a case that isn't covered by the tests though?

r? @camelid

[rust-highfive]

Some changes occurred in clean/types.rs.

cc @camelid

[GuillaumeGomez]

Let's check if there is an impact on perf:

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

[bors]

⌛ Trying commit b178b09 with merge 2ab0cef387112435a80c2aa6f3fad22792145372...

[rust-log-analyzer]

The job x86_64-gnu-llvm-12 failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

failures:

---- [rustdoc-json] src/test/rustdoc-json/primitive.rs stdout ----

error: jsondocck failed!
status: exit status: 1
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/jsondocck" "--doc-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-json/primitive" "--template" "/checkout/src/test/rustdoc-json/primitive.rs"
stdout: none
--- stderr -------------------------------
Failed check: `@!has - $.index[*][?(@.name=='is_ascii_uppercase')]` matched when it shouldn't on line 14
Error: "Jsondocck failed for /checkout/src/test/rustdoc-json/primitive.rs"

Rustdoc Output:
status: exit status: 0
status: exit status: 0
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustdoc" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-json/primitive/auxiliary" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-json/primitive" "--deny" "warnings" "/checkout/src/test/rustdoc-json/primitive.rs" "--edition=2018" "--output-format" "json" "-Zunstable-options"
stdout: none
stderr: none


failures:
    [rustdoc-json] src/test/rustdoc-json/primitive.rs

[GuillaumeGomez]

Seems like rustdoc-json has one failing test in the end. :)

[bors]

☀️ Try build successful - checks-actions
Build commit: 2ab0cef387112435a80c2aa6f3fad22792145372 (2ab0cef387112435a80c2aa6f3fad22792145372)

[rust-timer]

Queued 2ab0cef387112435a80c2aa6f3fad22792145372 with parent 09064a2, future comparison URL.

[rust-timer]

Finished benchmarking commit (2ab0cef387112435a80c2aa6f3fad22792145372): comparison url.

Summary:

• Primary benchmarks: 😿 relevant regressions found
• Secondary benchmarks: 😿 relevant regressions found

	Regressions 😿 (primary)	Regressions 😿 (secondary)	Improvements 🎉 (primary)	Improvements 🎉 (secondary)	All 😿 🎉 (primary)
count1	17	23	1	0	18
mean2	13.7%	29.6%	-0.3%	N/A	12.9%
max	43.3%	44.2%	-0.3%	N/A	43.3%

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf +perf-regression

Footnotes

1. number of relevant changes ↩

2. the arithmetic mean of the percent change ↩

[GuillaumeGomez]

That's quite the disaster. 😆

Oh well, now we know. :)

[camelid]

@GuillaumeGomez obviously, we can't land this as-is, but I think it might still be worth investigating a modification of this PR. My recollection is that BadImplStripper actually strips some impls that shouldn't be stripped. I'm pretty sure the regression is because more impls are being kept, so we should figure out what impls were being stripped before.