std: Refactor env::_var function

[xtqqczze]

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[rustbot]

r? @jhpratt

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[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[rust-log-analyzer]

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

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

REPOSITORY                                   TAG       IMAGE ID       CREATED      SIZE
ghcr.io/dependabot/dependabot-updater-core   latest    354d02aa29ac   7 days ago   783MB
=> Removing docker images...
Deleted Images:
untagged: ghcr.io/dependabot/dependabot-updater-core:latest
untagged: ghcr.io/dependabot/dependabot-updater-core@sha256:596da3f22bcbdff2c96fd7126001278022c834c1621c5efa2ad1a7794590636c
deleted: sha256:354d02aa29acf525570c732b6e006ecf138de6d63ca525d552eb4b24880ddc6c
deleted: sha256:8b7af0e426bc2cbeeacfd96b8354d3b80016991520977197e62090e47abaede8
deleted: sha256:cadf11ef1de7fdd5eab563757942353684047f09b212dc99d6ed48e8acf34d62
deleted: sha256:569b0caf9d5285db44ccd2629a3470139eea755be423a33a54d8a24cb3926bfa
deleted: sha256:f9dc5feb048d8f9fd43137e3998f59e9acfbd76c47a4e14984d109654119e282
---
tests/ui/drain_collect.fixed ... ok
tests/ui/double_parens.rs ... ok
tests/ui/duplicate_underscore_argument.rs ... ok
tests/ui/duplicated_attributes.rs ... ok
tests/ui/duration_suboptimal_units.rs ... ok
tests/ui/duration_suboptimal_units_days_weeks.rs ... ok
tests/ui/duration_subsec.rs ... ok
tests/ui/duration_suboptimal_units_days_weeks.fixed ... ok
tests/ui/double_parens.fixed ... ok
tests/ui/duration_suboptimal_units.fixed ... ok
tests/ui/duration_subsec.fixed ... ok
tests/ui/else_if_without_else.rs ... ok
tests/ui/elidable_lifetime_names.rs ... ok
---
[WARNING] line 39: Delta is 0 for "x", maybe try to use `compare-elements-position` instead?

======== tests/rustdoc-gui/setting-go-to-only-result.goml ========

[ERROR] setting-go-to-only-result output:
Execution context was destroyed, most likely because of a navigation.
stack: Error: Execution context was destroyed, most likely because of a navigation.
    at rewriteError (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/puppeteer-core/lib/cjs/puppeteer/cdp/ExecutionContext.js:457:15)
    at async #evaluate (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/puppeteer-core/lib/cjs/puppeteer/cdp/ExecutionContext.js:389:60)
    at async ExecutionContext.evaluate (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/puppeteer-core/lib/cjs/puppeteer/cdp/ExecutionContext.js:277:16)
    at async IsolatedWorld.evaluate (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/puppeteer-core/lib/cjs/puppeteer/cdp/IsolatedWorld.js:100:16)
    at async CdpFrame.evaluate (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/puppeteer-core/lib/cjs/puppeteer/api/Frame.js:362:20)
    at async CdpPage.evaluate (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/puppeteer-core/lib/cjs/puppeteer/api/Page.js:826:20)
    at async /checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/browser-ui-test/src/index.js:432:28
    at async waitForConditionTrue (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/browser-ui-test/src/utils.js:209:13)
    at async runAllCommands (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/browser-ui-test/src/index.js:431:22)
    at async innerRunTestCode (/checkout/obj/build/x86_64-unknown-linux-gnu/test/rustdoc-gui/node_modules/browser-ui-test/src/index.js:714:21)



<= doc-ui tests done: 146 succeeded, 1 failed, 0 filtered out