[crater] Make missing_fragment_specifier an unconditional error

[tgross35]

This was attempted in 1 then reverted in 2 because of fallout. Recently, this was made an edition-dependent error in 3.

Experiment with turning missing fragment specifiers an unconditional error again.

More context: #128006

Fixes: #40107

r? @petrochenkov

[tgross35]

This is just to test the diagnostics, none of the possible code cleanup is included.

@petrochenkov please take a look when you get the chance and start crater if the change seems correct.

@bors try

[bors]

⌛ Trying commit c2492ec with merge 063c08d...

[bors]

☀️ Try build successful - checks-actions
Build commit: 063c08d (063c08dd8db6ff113bb809c130456f1781abe72c)

[petrochenkov]

@craterbot check

[craterbot]

👌 Experiment pr-128425 created and queued.
🤖 Automatically detected try build 063c08d
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🚧 Experiment pr-128425 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🎉 Experiment pr-128425 is completed!
📊 156 regressed and 2 fixed (487733 total)
📰 Open the full report.

⚠️ If you notice any spurious failure please add them to the blacklist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[tgross35]

rg 'missing fragment specifier' -l --stats in the logs reports 373 matches. The previous attempt in 2020 had 475 regressions per #76605, so that is slight improvement but not much.

Like the previous run, almost all of these (361) come from clap <= 2.20, based on a crude rg 'missing fragment specifier.*\n.*clap' -l --stats -U. Remaining 12:

build-fail/reg/sem/0.1.0/master#83dcdb3a5dad0ed1e3e1fadc848d3f7727b41aa5.txt-[INFO] [stdout]    --> src/macros.rs:121:17
build-fail/reg/sem/0.1.0/master#83dcdb3a5dad0ed1e3e1fadc848d3f7727b41aa5.txt-[INFO] [stdout]    --> src/macros.rs:136:17
build-fail/reg/sem/0.1.0/master#83dcdb3a5dad0ed1e3e1fadc848d3f7727b41aa5.txt-[INFO] [stdout]    --> src/macros.rs:121:17
build-fail/reg/sem/0.1.0/master#83dcdb3a5dad0ed1e3e1fadc848d3f7727b41aa5.txt-[INFO] [stdout]    --> src/macros.rs:136:17
build-fail/reg/sem/0.1.0/try#063c08dd8db6ff113bb809c130456f1781abe72c.txt-[INFO] [stdout]    --> src/macros.rs:121:17
build-fail/reg/sem/0.1.0/try#063c08dd8db6ff113bb809c130456f1781abe72c.txt-[INFO] [stdout]    --> src/macros.rs:136:17
build-fail/reg/sem/0.1.0/try#063c08dd8db6ff113bb809c130456f1781abe72c.txt-[INFO] [stdout]    --> src/macros.rs:121:17
build-fail/reg/sem/0.1.0/try#063c08dd8db6ff113bb809c130456f1781abe72c.txt-[INFO] [stdout]    --> src/macros.rs:136:17
build-fail/reg/sem/0.1.0/try#063c08dd8db6ff113bb809c130456f1781abe72c.txt-[INFO] [stdout]    --> src/macros.rs:121:17
build-fail/reg/sem/0.1.0/try#063c08dd8db6ff113bb809c130456f1781abe72c.txt-[INFO] [stdout]    --> src/macros.rs:121:17
build-fail/reg/sem/0.1.0/try#063c08dd8db6ff113bb809c130456f1781abe72c.txt-[INFO] [stdout]    --> src/macros.rs:136:17
build-fail/reg/sem/0.1.0/try#063c08dd8db6ff113bb809c130456f1781abe72c.txt-[INFO] [stdout]    --> src/macros.rs:136:17

We could let this simmer for a while with the new error in deps level (#128122) and/or the edition-dependent lint (#128006). I don't really know how to feel about these results because all of the relevant clap versions have been yanked for ~4 years, per clap-rs/clap#2076.

Requesting compiler feedback for how to proceed. Context: this was made an e2024 error in #128006, making it an error in all editions is being considered here.

@rustbot label +I-compiler-nominated

[wesleywiser]

Discussed briefly in the compiler team triage meeting. Given that nearly all regressions are on very old versions of clap and this has been a compatibility warning since 2017, we think it's reasonable to make this an unconditional error.

[tgross35]

Thanks for discussing this. I'll wait for the next beta branch so #128122 is on stable for at least a cycle, then continue pushing this forward.

[tgross35]

To reflect my above comment

@rustbot blocked

[petrochenkov]

Thanks for discussing this. I'll wait for the next beta branch so #128122 is on stable for at least a cycle, then continue pushing this forward.

@tgross35 Do you plan to return to this? The mentioned beta branch was released long time ago.

[tgross35]

Yeah, that came and went. I'll get this rebased soon, should probably rerun crater to see if anything improved.

[tgross35]

@bors try

[bors]

⌛ Trying commit d1ce28d with merge d124845...

[rust-log-analyzer]

The job x86_64-gnu-llvm-18 failed! Check out the build log: (web) (plain)

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

#21 exporting to docker image format
#21 sending tarball 28.1s done
#21 DONE 41.2s
##[endgroup]
Setting extra environment values for docker:  --env ENABLE_GCC_CODEGEN=1 --env GCC_EXEC_PREFIX=/usr/lib/gcc/
[CI_JOB_NAME=x86_64-gnu-llvm-18]
debug: `DISABLE_CI_RUSTC_IF_INCOMPATIBLE` configured.
---
sccache: Listening on address 127.0.0.1:4226
##[group]Configure the build
configure: processing command line
configure: 
configure: build.configure-args := ['--build=x86_64-unknown-linux-gnu', '--llvm-root=/usr/lib/llvm-18', '--enable-llvm-link-shared', '--set', 'rust.randomize-layout=true', '--set', 'rust.thin-lto-import-instr-limit=10', '--enable-verbose-configure', '--enable-sccache', '--disable-manage-submodules', '--enable-locked-deps', '--enable-cargo-native-static', '--set', 'rust.codegen-units-std=1', '--set', 'dist.compression-profile=balanced', '--dist-compression-formats=xz', '--set', 'rust.lld=false', '--disable-dist-src', '--release-channel=nightly', '--enable-debug-assertions', '--enable-overflow-checks', '--enable-llvm-assertions', '--set', 'rust.verify-llvm-ir', '--set', 'rust.codegen-backends=llvm,cranelift,gcc', '--set', 'llvm.static-libstdcpp', '--enable-new-symbol-mangling']
configure: target.x86_64-unknown-linux-gnu.llvm-config := /usr/lib/llvm-18/bin/llvm-config
configure: llvm.link-shared     := True
configure: rust.randomize-layout := True
configure: rust.thin-lto-import-instr-limit := 10
---
  Downloaded boml v0.3.1
   Compiling boml v0.3.1
   Compiling y v0.1.0 (/checkout/compiler/rustc_codegen_gcc/build_system)
    Finished `release` profile [optimized] target(s) in 4.19s
     Running `/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-codegen/x86_64-unknown-linux-gnu/release/y test --use-system-gcc --use-backend gcc --out-dir /checkout/obj/build/x86_64-unknown-linux-gnu/stage1-tools/cg_gcc --release --mini-tests --std-tests`
Using system GCC
warning: target feature `x87` must be enabled to ensure that the ABI of the current target can be implemented correctly
  |
  = note: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
  = note: for more information, see issue #116344 <https://github.com/rust-lang/rust/issues/116344>
---
failures:

---- broken_fragment_local stdout ----

thread 'broken_fragment_local' panicked at src/tools/linkchecker/tests/checks.rs:17:5:
assertion failed: !status.success()

---- broken_fragment_remote stdout ----


thread 'broken_fragment_remote' panicked at src/tools/linkchecker/tests/checks.rs:17:5:
assertion failed: !status.success()

failures:
    broken_fragment_local
    broken_fragment_remote

[bors]

☀️ Try build successful - checks-actions
Build commit: d124845 (d12484522bcab8d07e325c6570f226a2faace3f7)

[tgross35]

The PR CI is just stuck on linkcheck. Cratering again to see if anything has changed since the error upgrades.

@craterbot check

[craterbot]

👌 Experiment pr-128425-1 created and queued.
🤖 Automatically detected try build d124845
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🚧 Experiment pr-128425-1 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🎉 Experiment pr-128425-1 is completed!
📊 140 regressed and 0 fixed (589170 total)
📰 Open the full report.

⚠️ If you notice any spurious failure please add them to the denylist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[petrochenkov]

Waiting on author to analyze the regressions and fix CI.
@rustbot author