build(profiling): clean up cfg checks for MSRV 1.80+

[morrisonlevi]

Description

We migrated to Rust 1.84 in #3299, which was 7 months ago. Time to clean it up.

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[datadog-datadog-prod-us1]

⚠️ Tests

✨ Fix all issues with Cursor

⚠️ Warnings

🧪 1024 Tests failed

    testSearchPhpBinaries from integration.DDTrace\Tests\Integration\PHPInstallerTest (Fix with Cursor)

    testSimplePushAndProcess from laravel-58-test.DDTrace\Tests\Integrations\Laravel\V5_8\QueueTest (Fix with Cursor)

testSimplePushAndProcess from laravel-8x-test.DDTrace\Tests\Integrations\Laravel\V8_x\QueueTest (Datadog) (Fix with Cursor)

DDTrace\Tests\Integrations\Laravel\V8_x\QueueTest::testSimplePushAndProcess
Test code or tested code printed unexpected output: spanLinksTraceId: 69790d15000000007cdffd52474c6a79
tid: 69790d1500000000
hexProcessTraceId: 7cdffd52474c6a79
hexProcessSpanId: 472af97bc8f5257b
processTraceId: 8998189110334876281
processSpanId: 5128185435762533755

View all

ℹ️ Info

❄️ No new flaky tests detected

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: f1806dd | Docs | Datadog PR Page | Was this helpful? Give us feedback!}

[pr-commenter]

Benchmarks [ profiler ]

Benchmark execution time: 2026-01-27 18:13:18

Comparing candidate commit f1806dd in PR branch chore/msrv-checkcfg with baseline commit c4d4325 in branch master.

Found 1 performance improvements and 2 performance regressions! Performance is the same for 26 metrics, 7 unstable metrics.

scenario:php-profiler-timeline-memory-control

• 🟥 cpu_user_time [+29.871ms; +39.681ms] or [+4.900%; +6.509%]
• 🟥 execution_time [+34.240ms; +38.420ms] or [+5.374%; +6.030%]

scenario:walk_stack/1

• 🟩 wall_time [-266.902ns; -260.539ns] or [-2.093%; -2.043%]

[realFlowControl]

Nice, I guess we can also remove the rustc_version dependency from the Cargo.toml now?

[build-dependencies]
bindgen = { version = \"0.69.4\" }
cc = { version = \"1.0\" }
-
-# We can remove this when we're using Rust 1.80+
-rustc_version = \"0.4\"

[morrisonlevi]

Nice, I guess we can also remove the rustc_version dependency from the Cargo.toml now?

[build-dependencies]
bindgen = { version = \"0.69.4\" }
cc = { version = \"1.0\" }
-
-# We can remove this when we're using Rust 1.80+
-rustc_version = \"0.4\"

Yes, I dropped this! Nice eye.