diff options
Diffstat (limited to 'src/libsyntax_ext')
| -rw-r--r-- | src/libsyntax_ext/deriving/mod.rs | 94 |
1 files changed, 64 insertions, 30 deletions
diff --git a/src/libsyntax_ext/deriving/mod.rs b/src/libsyntax_ext/deriving/mod.rs index 92a141fb4ec..4ca3196b9c5 100644 --- a/src/libsyntax_ext/deriving/mod.rs +++ b/src/libsyntax_ext/deriving/mod.rs @@ -96,6 +96,36 @@ fn expand_derive(cx: &mut ExtCtxt, let mut found_partial_eq = false; let mut found_eq = false; + // This span is **very** sensitive and crucial to + // getting the stability behavior we want. What we are + // doing is marking the generated `#[derive_*]` with the + // span of the `#[deriving(...)]` attribute (the + // entire attribute, not just the `PartialEq` or `Eq` + // part), but with the current backtrace. The current + // backtrace will contain a topmost entry that IS this + // `#[deriving(...)]` attribute and with the + // "allow-unstable" flag set to true. + // + // Note that we do NOT use the span of the `Eq` + // text itself. You might think this is + // equivalent, because the `Eq` appears within the + // `#[deriving(Eq)]` attribute, and hence we would + // inherit the "allows unstable" from the + // backtrace. But in fact this is not always the + // case. The actual source text that led to + // deriving can be `#[$attr]`, for example, where + // `$attr == deriving(Eq)`. In that case, the + // "#[derive_*]" would be considered to + // originate not from the deriving call but from + // text outside the deriving call, and hence would + // be forbidden from using unstable + // content. + // + // See tests src/run-pass/rfc1445 for + // examples. --nmatsakis + let span = Span { expn_id: cx.backtrace(), .. span }; + assert!(cx.parse_sess.codemap().span_allows_unstable(span)); + for titem in traits.iter().rev() { let tname = match titem.node { MetaItemKind::Word(ref tname) => tname, @@ -121,42 +151,13 @@ fn expand_derive(cx: &mut ExtCtxt, } // #[derive(Foo, Bar)] expands to #[derive_Foo] #[derive_Bar] - item.attrs.push(cx.attribute(titem.span, cx.meta_word(titem.span, + item.attrs.push(cx.attribute(span, cx.meta_word(titem.span, intern_and_get_ident(&format!("derive_{}", tname))))); } // RFC #1445. `#[derive(PartialEq, Eq)]` adds a (trusted) // `#[structural_match]` attribute. if found_partial_eq && found_eq { - // This span is **very** sensitive and crucial to - // getting the stability behavior we want. What we are - // doing is marking `#[structural_match]` with the - // span of the `#[deriving(...)]` attribute (the - // entire attribute, not just the `PartialEq` or `Eq` - // part), but with the current backtrace. The current - // backtrace will contain a topmost entry that IS this - // `#[deriving(...)]` attribute and with the - // "allow-unstable" flag set to true. - // - // Note that we do NOT use the span of the `Eq` - // text itself. You might think this is - // equivalent, because the `Eq` appears within the - // `#[deriving(Eq)]` attribute, and hence we would - // inherit the "allows unstable" from the - // backtrace. But in fact this is not always the - // case. The actual source text that led to - // deriving can be `#[$attr]`, for example, where - // `$attr == deriving(Eq)`. In that case, the - // "#[structural_match]" would be considered to - // originate not from the deriving call but from - // text outside the deriving call, and hence would - // be forbidden from using unstable - // content. - // - // See tests src/run-pass/rfc1445 for - // examples. --nmatsakis - let span = Span { expn_id: cx.backtrace(), .. span }; - assert!(cx.parse_sess.codemap().span_allows_unstable(span)); debug!("inserting structural_match with span {:?}", span); let structural_match = intern_and_get_ident("structural_match"); item.attrs.push(cx.attribute(span, @@ -188,6 +189,39 @@ macro_rules! derive_traits { mitem: &MetaItem, annotatable: &Annotatable, push: &mut FnMut(Annotatable)) { + if !ecx.parse_sess.codemap().span_allows_unstable(sp) + && !ecx.ecfg.features.unwrap().custom_derive { + // FIXME: + // https://github.com/rust-lang/rust/pull/32671#issuecomment-206245303 + // This is just to avoid breakage with syntex. + // Remove that to spawn an error instead. + let cm = ecx.parse_sess.codemap(); + let parent = cm.with_expn_info(ecx.backtrace(), + |info| info.unwrap().call_site.expn_id); + cm.with_expn_info(parent, |info| { + if info.is_some() { + let mut w = ecx.parse_sess.span_diagnostic.struct_span_warn( + sp, feature_gate::EXPLAIN_DERIVE_UNDERSCORE, + ); + if option_env!("CFG_DISABLE_UNSTABLE_FEATURES").is_none() { + w.fileline_help( + sp, &format!("add #![feature(custom_derive)] to \ + the crate attributes to enable") + ); + } + w.emit(); + } else { + feature_gate::emit_feature_err( + &ecx.parse_sess.span_diagnostic, + "custom_derive", sp, feature_gate::GateIssue::Language, + feature_gate::EXPLAIN_DERIVE_UNDERSCORE + ); + + return; + } + }) + } + warn_if_deprecated(ecx, sp, $name); $func(ecx, sp, mitem, annotatable, push); } |