#[doc = $expr] in macro silently fails to generate docs

[Manishearth]

#![warn(missing_docs)]

//! la la la

macro_rules! make_enum {
    ($(($name:ident, $string:expr)),+) => {
        /// la la la
        pub enum Foo {
            $(
                #[doc = $string]
                $name,
            )+
        }
    }
}

make_enum!{(A, "a"), (B, "b"), (C, "c")}

This will not generate docs for the generated enum, and will warn about missing docs on the enum variant. (missing_docs is off by default, so normally you wouldn't notice this)

This is a rustc bug, not a rustdoc bug, since the lint fails too (so we're somehow losing the doc attribute entirely). This works fine on beta.

cc @eddyb

[Manishearth]

This is a regression introduced in today's nightly (rustc 1.22.0-nightly (325ba23 2017-09-19))

325ba23 Auto merge of #44620 - zackmdavis:rfc_1940_housekeeping, r=nikomatsakis

5d5dcae Auto merge of #44601 - alexcrichton:lower-attributes-in-hir, r=nrc

9a00f3c Auto merge of #44026 - QuietMisdreavus:trimmed-std, r=steveklabnik

0694e4f rustc: Forbid interpolated tokens in the HIR

06bb0e0 Auto merge of #44680 - infinity0:master, r=Mark-Simulacrum

8f25497 rustbuild: with --no-fail-fast, report the specific commands that failed

0701b37 Auto merge of #44678 - alexcrichton:rollup, r=alexcrichton

929215d Rollup merge of #44671 - GuillaumeGomez:run-button, r=steveklabnik

4af3073 Rollup merge of #44668 - iwillspeak:into-iterator-docs, r=steveklabnik

3bbe153 Rollup merge of #44661 - GuillaumeGomez:more-links, r=QuietMisdreavus

64c9fd6 Rollup merge of #44657 - Ixrec:patch-1, r=eddyb

d5b0cbb Rollup merge of #44651 - bluss:document-thread-name-no-nuls, r=steveklabnik

fa9dd27 Rollup merge of #44640 - budziq:stabilize_splice, r=dtolnay

156698e Rollup merge of #44548 - oyvindln:rustc_help_fix, r=arielb1

8dae2b0 Rollup merge of #44537 - oli-obk:memchr, r=alexcrichton

fbf3b8a Rollup merge of #44466 - clarcharr:cow_error, r=alexcrichton

9ad5473 Rollup merge of #44364 - michaelwoerister:hash-all-the-things2, r=nikomatsakis

90ce24a Fix run button

4961a8e incr.comp.: Fix ICE caused by trying to hash INVALID_CRATE_NUM.

74d6b85 incr.comp.: Fix rebase fallout.

d5b1fee incr.comp.: Remove tcx from StableHashingContext.

ba6f93c incr.comp.: Make the StableHashingContext mostly independent of the tcx.

e567afb incr.comp.: Initialize IGNORED_ATTRS in StableHashingContext lazily.

dd50173 incr.comp.: Initialize the CachingCodemapView in StableHashingContext lazily.

67c84e0 incr.comp.: Use StableHash impls instead of functions for hashing most maps.

b9816c5 incr.comp.: Already hash HIR bodies during metadata export so they don't have to be hashed in downstream crates.

e3f9131 Fix issues uncovered by rebasing:

3cc3ae2 incr.comp.: Move result fingerprinting to DepGraph::with_task().

e6c9a53 incr.comp.: Compute hashes of all query results.

3cf28f3 Use DefId instead of NodeId as identifier in resolve_lifetime::Region.

3a7b960 Auto merge of #44441 - tamird:cargo-bitflags, r=alexcrichton

ebd0e4f Add Example of IntoIterator as Trait Bound to Docs

caad256 Auto merge of #43628 - oli-obk:orbital_standard_library, r=alexcrichton

e8a76d8 Auto merge of #44529 - alexcrichton:trans-query, r=michaelwoerister

e47279f Add more links and put the link character to the left

01555b1 Rebase fallout

a9df19b Update miri submodule

68fc65e Prevent distribution if miri is enabled

13921da -Zmir-emit-validate is in stage 0

ab018c7 Add a file to trivially disable tool building or testing

f0b5402 Improve documentation

f381744 Get the miri test suite to run inside the rustc dev environment

2787a28 Add <*const T>::align_offset and use it in memchr

231d9e7 Remove rustc_bitflags; use the bitflags crate

6d614dd rustc: Move codegen to a query

e788fa7 bootstrap: plumb verbosity into submodule ops

4a8933f Use double quotes to appease some TOML parsers

3021c1d rustc: Attach an mpsc channel to TyCtxt

2eada58 rustc: Remove another global map from trans

19727c8 rustc: Move a comment to the right spot in trans

afb85cf rustc: Mostly remove ExportedSymbols

8821aff rustc: Move some attr methods to queries

132bde7 rustc: Make trans collect/partition a query

dba3ddd rustc: Calculate ExportedSymbols in a query

baca9a6 rustc: Use reachablility through a query

a97ad6a rustc: Refactor trans paritioning to use tcx

c72240a rustc_trans: Refactor collection to use tcx

38fa340 missed a 'mut'

2633b85 Replace str's transmute() calls with pointer casts

6b167f9 Updated tracking issue for String::splice and its unstable-book entry

7b932d2 stabilized vec_splice (fixes #32310)

7859c9e std: Document thread builder panics for nul bytes in thread names

d09db63 unstable book section for fn_must_use

e9569d9 RFC 1940 UI test in own directory, exercise must_use trait methods

e89748e Remove the other period and start with lowercase for more consistency

edf1622 Add proper help line for inline threshold

778d5f2 Add Cow -> Box impls.

64f6111 remove tests for doc(masked)

db09332 update doc_masked docs and tracking issue

bb6de3c add feature gate doc_masked and tests

c491e19 new attribute #[doc(masked)] to hide internal crates from std docs

[kennytm]

I suspect #44601 (very likely) or #44026 (less likely).

[Manishearth]

This seems to apply to any kind of attribute, not just doc attributes (and not just the #[doc = "string"] form:

macro_rules! never {
    ($inline:ident) => {
        #[inline($inline)]
        pub fn foo(x: u8) -> u8 { x * x}
    }
}
never!{never}

does not generate noinline in the LLVM IR

Similarly, doing something like this with #[repr(nonsense)] will not trigger the repr error. Seems like these attributes get discarded early.

[Manishearth]

Looks like early lint passes do detect these attributes, it is late lint passes which have trouble here. So it's on the HIR side.

[Manishearth]

Yep, it was regressed by #44601

[eddyb]

Well, cc-ing @alexcrichton (and/or @rust-lang/compiler) seems more appropriate.

[alexcrichton]

I'm working on a fix for this

[alexcrichton]

I've posted a fix at #44745