Tweak may_dangle syntax for MCP 563

[SoniEx2]

(don't mind us just using CI for development)

[rustbot]

r? @petrochenkov

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

[compiler-errors]

future note: It's good practice to mark as a draft and r? @ghost for PRs that are still in development

[SoniEx2]

oh. does CI run on drafts...? we thought it didn't?

but yes, noted about the r?, sorry >.<

[rust-log-analyzer]

The job x86_64-gnu-llvm-13 failed! Check out the build log: (web) (plain)

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

..........................................i.ii.......................................... 14168/14233
.................................................................
failures:

---- [ui] tests/ui/dropck/mcp563-dropck-eyepatch-syntax.rs stdout ----
error: ui test compiled successfully!
status: exit status: 0
status: exit status: 0
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/dropck/mcp563-dropck-eyepatch-syntax.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Zdeduplicate-diagnostics=no" "-Cstrip=debuginfo" "--remap-path-prefix=/checkout/tests/ui=fake-test-src-base" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/dropck/mcp563-dropck-eyepatch-syntax" "-A" "unused" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/dropck/mcp563-dropck-eyepatch-syntax/auxiliary"
stdout: none
stderr: none


failures:
failures:
    [ui] tests/ui/dropck/mcp563-dropck-eyepatch-syntax.rs
test result: FAILED. 14096 passed; 1 failed; 136 ignored; 0 measured; 0 filtered out; finished in 141.92s

Some tests failed in compiletest suite=ui mode=ui host=x86_64-unknown-linux-gnu target=x86_64-unknown-linux-gnu
Build completed unsuccessfully in 0:14:50

[SoniEx2]

hmm, actually unsure how to proceed. gonna wait for a fix for #107231 and see what we can do from there.

[clubby789]

This could be fixed without changing attribute validation globally, the used attribute denies other words like this:

rust/compiler/rustc_codegen_ssa/src/codegen_attrs.rs

Lines 153 to 182 in c8e6a9e

	} else if attr.has_name(sym::used) {
	let inner = attr.meta_item_list();
	match inner.as_deref() {
	Some([item]) if item.has_name(sym::linker) => {
	if !tcx.features().used_with_arg {
	feature_err(
	&tcx.sess.parse_sess,
	sym::used_with_arg,
	attr.span,
	"`#[used(linker)]` is currently unstable",
	)
	.emit();
	}
	codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_LINKER;
	}
	Some([item]) if item.has_name(sym::compiler) => {
	if !tcx.features().used_with_arg {
	feature_err(
	&tcx.sess.parse_sess,
	sym::used_with_arg,
	attr.span,
	"`#[used(compiler)]` is currently unstable",
	)
	.emit();
	}
	codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
	}
	Some(_) => {
	tcx.sess.emit_err(ExpectedUsedSymbol { span: attr.span });
	}

[JohnCSimon]

@SoniEx2
ping from triage - what is the status of this PR?

FYI: when a PR is ready for review, please send a message containing
@rustbot ready to switch to S-waiting-on-review so the PR is in the reviewer's backlog.

[SoniEx2]

we aren't entirely sure how to do this. also waiting for feedback on rust-lang/rfcs#3390 because that happened.