syntax: Migrate built-in macros to the regular stability checking

Author: petrochenkov

src/librustc_resolve/lib.rs

@@ -1684,6 +1684,9 @@ pub struct Resolver<'a> {
     current_type_ascription: Vec<Span>,
 
     injected_crate: Option<Module<'a>>,
+
+    /// Features enabled for this crate.
+    active_features: FxHashSet<Symbol>,
 }
 
 /// Nothing really interesting here; it just provides memory for the rest of the crate.
@@ -1922,6 +1925,7 @@ impl<'a> Resolver<'a> {
         let mut macro_defs = FxHashMap::default();
         macro_defs.insert(Mark::root(), root_def_id);
 
+        let features = session.features_untracked();
         let non_macro_attr = |mark_used| Lrc::new(SyntaxExtension::default(
             SyntaxExtensionKind::NonMacroAttr { mark_used }, session.edition()
         ));
@@ -2009,6 +2013,10 @@ impl<'a> Resolver<'a> {
             unused_macros: Default::default(),
             current_type_ascription: Vec::new(),
             injected_crate: None,
+            active_features:
+                features.declared_lib_features.iter().map(|(feat, ..)| *feat)
+                    .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat))
+                    .collect(),
         }
     }
 

src/librustc_resolve/macros.rs

@@ -1013,9 +1013,8 @@ impl<'a> Resolver<'a> {
     fn check_stability_and_deprecation(&self, ext: &SyntaxExtension, path: &str, span: Span) {
         if let Some(stability) = &ext.stability {
             if let StabilityLevel::Unstable { reason, issue } = stability.level {
-                let (feature, features) = (stability.feature, self.session.features_untracked());
-                if !span.allows_unstable(feature) &&
-                   features.declared_lib_features.iter().all(|(feat, _)| *feat != feature) {
+                let feature = stability.feature;
+                if !self.active_features.contains(&feature) && !span.allows_unstable(feature) {
                     stability::report_unstable(self.session, feature, reason, issue, span);
                 }
             }

src/libserialize/json.rs

@@ -103,6 +103,7 @@
 //!
 //! ```rust
 //! # #![feature(rustc_private)]
+//! # #![allow(deprecated)]
 //! extern crate serialize;
 //! use serialize::json::{self, ToJson, Json};
 //!
@@ -143,6 +144,7 @@
 //!
 //! ```rust
 //! # #![feature(rustc_private)]
+//! # #![allow(deprecated)]
 //! extern crate serialize;
 //! use std::collections::BTreeMap;
 //! use serialize::json::{self, Json, ToJson};

src/libsyntax/attr/builtin.rs

@@ -135,6 +135,19 @@ pub enum StabilityLevel {
     Stable { since: Symbol },
 }
 
+impl Stability {
+    pub fn unstable(feature: Symbol, reason: Option<Symbol>, issue: u32) -> Stability {
+        Stability {
+            level: StabilityLevel::Unstable { reason, issue },
+            feature,
+            rustc_depr: None,
+            const_stability: None,
+            promotable: false,
+            allow_const_fn_ptr: false,
+        }
+    }
+}
+
 impl StabilityLevel {
     pub fn is_unstable(&self) -> bool {
         if let StabilityLevel::Unstable {..} = *self {

src/libsyntax/ext/expand.rs

@@ -487,7 +487,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
 
     fn expand_invoc(&mut self, invoc: Invocation, ext: &SyntaxExtension) -> Option<AstFragment> {
         if invoc.fragment_kind == AstFragmentKind::ForeignItems &&
-           !self.cx.ecfg.macros_in_extern_enabled() {
+           !self.cx.ecfg.macros_in_extern() {
             if let SyntaxExtensionKind::NonMacroAttr { .. } = ext.kind {} else {
                 emit_feature_err(&self.cx.parse_sess, sym::macros_in_extern,
                                  invoc.span(), GateIssue::Language,
@@ -919,7 +919,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                         })
                         .map(|i| attrs.remove(i));
         if let Some(attr) = &attr {
-            if !self.cx.ecfg.enable_custom_inner_attributes() &&
+            if !self.cx.ecfg.custom_inner_attributes() &&
                attr.style == ast::AttrStyle::Inner && attr.path != sym::test {
                 emit_feature_err(&self.cx.parse_sess, sym::custom_inner_attributes,
                                  attr.span, GateIssue::Language,
@@ -1432,19 +1432,6 @@ pub struct ExpansionConfig<'feat> {
     pub keep_macs: bool,
 }
 
-macro_rules! feature_tests {
-    ($( fn $getter:ident = $field:ident, )*) => {
-        $(
-            pub fn $getter(&self) -> bool {
-                match self.features {
-                    Some(&Features { $field: true, .. }) => true,
-                    _ => false,
-                }
-            }
-        )*
-    }
-}
-
 impl<'feat> ExpansionConfig<'feat> {
     pub fn default(crate_name: String) -> ExpansionConfig<'static> {
         ExpansionConfig {
@@ -1458,20 +1445,13 @@ impl<'feat> ExpansionConfig<'feat> {
         }
     }
 
-    feature_tests! {
-        fn enable_asm = asm,
-        fn enable_custom_test_frameworks = custom_test_frameworks,
-        fn enable_global_asm = global_asm,
-        fn enable_log_syntax = log_syntax,
-        fn enable_concat_idents = concat_idents,
-        fn enable_trace_macros = trace_macros,
-        fn enable_allow_internal_unstable = allow_internal_unstable,
-        fn enable_format_args_nl = format_args_nl,
-        fn macros_in_extern_enabled = macros_in_extern,
-        fn proc_macro_hygiene = proc_macro_hygiene,
+    fn macros_in_extern(&self) -> bool {
+        self.features.map_or(false, |features| features.macros_in_extern)
     }
-
-    fn enable_custom_inner_attributes(&self) -> bool {
+    fn proc_macro_hygiene(&self) -> bool {
+        self.features.map_or(false, |features| features.proc_macro_hygiene)
+    }
+    fn custom_inner_attributes(&self) -> bool {
         self.features.map_or(false, |features| features.custom_inner_attributes)
     }
 }

src/libsyntax/ext/source_util.rs

@@ -4,7 +4,7 @@ use crate::ext::build::AstBuilder;
 use crate::parse::{self, token, DirectoryOwnership};
 use crate::print::pprust;
 use crate::ptr::P;
-use crate::symbol::{Symbol, sym};
+use crate::symbol::Symbol;
 use crate::tokenstream;
 
 use smallvec::SmallVec;
@@ -41,16 +41,6 @@ pub fn expand_column(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTr
     base::MacEager::expr(cx.expr_u32(topmost, loc.col.to_usize() as u32 + 1))
 }
 
-/* __rust_unstable_column!(): expands to the current column number */
-pub fn expand_column_gated(cx: &mut ExtCtxt<'_>, sp: Span, tts: &[tokenstream::TokenTree])
-                  -> Box<dyn base::MacResult+'static> {
-    if sp.allows_unstable(sym::__rust_unstable_column) {
-        expand_column(cx, sp, tts)
-    } else {
-        cx.span_fatal(sp, "the __rust_unstable_column macro is unstable");
-    }
-}
-
 /// file!(): expands to the current filename */
 /// The source_file (`loc.file`) contains a bunch more information we could spit
 /// out if we wanted.

src/libsyntax/feature_gate.rs

@@ -1568,7 +1568,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     (sym::type_length_limit, CrateLevel, template!(NameValueStr: "N"), Ungated),
     (sym::test_runner, CrateLevel, template!(List: "path"), Gated(Stability::Unstable,
                     sym::custom_test_frameworks,
-                    EXPLAIN_CUSTOM_TEST_FRAMEWORKS,
+                    "custom test frameworks are an unstable feature",
                     cfg_fn!(custom_test_frameworks))),
 ];
 
@@ -1819,26 +1819,6 @@ const EXPLAIN_BOX_SYNTAX: &str =
 pub const EXPLAIN_STMT_ATTR_SYNTAX: &str =
     "attributes on expressions are experimental";
 
-pub const EXPLAIN_ASM: &str =
-    "inline assembly is not stable enough for use and is subject to change";
-
-pub const EXPLAIN_GLOBAL_ASM: &str =
-    "`global_asm!` is not stable enough for use and is subject to change";
-
-pub const EXPLAIN_CUSTOM_TEST_FRAMEWORKS: &str =
-    "custom test frameworks are an unstable feature";
-
-pub const EXPLAIN_LOG_SYNTAX: &str =
-    "`log_syntax!` is not stable enough for use and is subject to change";
-
-pub const EXPLAIN_CONCAT_IDENTS: &str =
-    "`concat_idents` is not stable enough for use and is subject to change";
-
-pub const EXPLAIN_FORMAT_ARGS_NL: &str =
-    "`format_args_nl` is only for internal language use and is subject to change";
-
-pub const EXPLAIN_TRACE_MACROS: &str =
-    "`trace_macros` is not stable enough for use and is subject to change";
 pub const EXPLAIN_ALLOW_INTERNAL_UNSTABLE: &str =
     "allow_internal_unstable side-steps feature gating and stability checks";
 pub const EXPLAIN_ALLOW_INTERNAL_UNSAFE: &str =

src/libsyntax_ext/asm.rs

@@ -8,7 +8,6 @@ use errors::DiagnosticBuilder;
 
 use syntax::ast;
 use syntax::ext::base::{self, *};
-use syntax::feature_gate;
 use syntax::parse;
 use syntax::parse::token::{self, Token};
 use syntax::ptr::P;
@@ -46,14 +45,6 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt<'_>,
                        sp: Span,
                        tts: &[tokenstream::TokenTree])
                        -> Box<dyn base::MacResult + 'cx> {
-    if !cx.ecfg.enable_asm() {
-        feature_gate::emit_feature_err(&cx.parse_sess,
-                                       sym::asm,
-                                       sp,
-                                       feature_gate::GateIssue::Language,
-                                       feature_gate::EXPLAIN_ASM);
-    }
-
     let mut inline_asm = match parse_inline_asm(cx, sp, tts) {
         Ok(Some(inline_asm)) => inline_asm,
         Ok(None) => return DummyResult::expr(sp),

src/libsyntax_ext/concat_idents.rs

@@ -2,25 +2,16 @@ use rustc_data_structures::thin_vec::ThinVec;
 
 use syntax::ast;
 use syntax::ext::base::{self, *};
-use syntax::feature_gate;
 use syntax::parse::token::{self, Token};
 use syntax::ptr::P;
 use syntax_pos::Span;
-use syntax_pos::symbol::{Symbol, sym};
+use syntax_pos::symbol::Symbol;
 use syntax::tokenstream::TokenTree;
 
 pub fn expand_syntax_ext<'cx>(cx: &'cx mut ExtCtxt<'_>,
                               sp: Span,
                               tts: &[TokenTree])
                               -> Box<dyn base::MacResult + 'cx> {
-    if !cx.ecfg.enable_concat_idents() {
-        feature_gate::emit_feature_err(&cx.parse_sess,
-                                       sym::concat_idents,
-                                       sp,
-                                       feature_gate::GateIssue::Language,
-                                       feature_gate::EXPLAIN_CONCAT_IDENTS);
-    }
-
     if tts.is_empty() {
         cx.span_err(sp, "concat_idents! takes 1 or more arguments.");
         return DummyResult::any(sp);

src/libsyntax_ext/deriving/decodable.rs

@@ -3,7 +3,6 @@
 use crate::deriving::{self, pathvec_std};
 use crate::deriving::generic::*;
 use crate::deriving::generic::ty::*;
-use crate::deriving::warn_if_deprecated;
 
 use syntax::ast;
 use syntax::ast::{Expr, MetaItem, Mutability};
@@ -26,7 +25,6 @@ pub fn expand_deriving_decodable(cx: &mut ExtCtxt<'_>,
                                  mitem: &MetaItem,
                                  item: &Annotatable,
                                  push: &mut dyn FnMut(Annotatable)) {
-    warn_if_deprecated(cx, span, "Decodable");
     expand_deriving_decodable_imp(cx, span, mitem, item, push, "serialize")
 }
 

src/libsyntax_ext/deriving/encodable.rs

@@ -85,7 +85,6 @@
 use crate::deriving::{self, pathvec_std};
 use crate::deriving::generic::*;
 use crate::deriving::generic::ty::*;
-use crate::deriving::warn_if_deprecated;
 
 use syntax::ast::{Expr, ExprKind, MetaItem, Mutability};
 use syntax::ext::base::{Annotatable, ExtCtxt};
@@ -107,7 +106,6 @@ pub fn expand_deriving_encodable(cx: &mut ExtCtxt<'_>,
                                  mitem: &MetaItem,
                                  item: &Annotatable,
                                  push: &mut dyn FnMut(Annotatable)) {
-    warn_if_deprecated(cx, span, "Encodable");
     expand_deriving_encodable_imp(cx, span, mitem, item, push, "serialize")
 }
 

src/libsyntax_ext/deriving/mod.rs

@@ -2,6 +2,7 @@
 
 use rustc_data_structures::sync::Lrc;
 use syntax::ast::{self, MetaItem};
+use syntax::attr::Deprecation;
 use syntax::edition::Edition;
 use syntax::ext::base::{Annotatable, ExtCtxt, Resolver, MultiItemModifier};
 use syntax::ext::base::{SyntaxExtension, SyntaxExtensionKind};
@@ -60,7 +61,7 @@ impl MultiItemModifier for BuiltinDerive {
 }
 
 macro_rules! derive_traits {
-    ($( $name:expr => $func:path, )+) => {
+    ($( [$deprecation:expr] $name:expr => $func:path, )+) => {
         pub fn is_builtin_trait(name: ast::Name) -> bool {
             match &*name.as_str() {
                 $( $name )|+ => true,
@@ -81,6 +82,10 @@ macro_rules! derive_traits {
                 resolver.add_builtin(
                     ast::Ident::with_empty_ctxt(Symbol::intern($name)),
                     Lrc::new(SyntaxExtension {
+                        deprecation: $deprecation.map(|msg| Deprecation {
+                            since: Some(Symbol::intern("1.0.0")),
+                            note: Some(Symbol::intern(msg)),
+                        }),
                         allow_internal_unstable: allow_internal_unstable.clone(),
                         ..SyntaxExtension::default(
                             SyntaxExtensionKind::LegacyDerive(Box::new(BuiltinDerive($func))),
@@ -94,44 +99,43 @@ macro_rules! derive_traits {
 }
 
 derive_traits! {
+    [None]
     "Clone" => clone::expand_deriving_clone,
 
+    [None]
     "Hash" => hash::expand_deriving_hash,
 
+    [None]
     "RustcEncodable" => encodable::expand_deriving_rustc_encodable,
 
+    [None]
     "RustcDecodable" => decodable::expand_deriving_rustc_decodable,
 
+    [None]
     "PartialEq" => partial_eq::expand_deriving_partial_eq,
+    [None]
     "Eq" => eq::expand_deriving_eq,
+    [None]
     "PartialOrd" => partial_ord::expand_deriving_partial_ord,
+    [None]
     "Ord" => ord::expand_deriving_ord,
 
+    [None]
     "Debug" => debug::expand_deriving_debug,
 
+    [None]
     "Default" => default::expand_deriving_default,
 
+    [None]
     "Copy" => bounds::expand_deriving_copy,
 
     // deprecated
+    [Some("derive(Encodable) is deprecated in favor of derive(RustcEncodable)")]
     "Encodable" => encodable::expand_deriving_encodable,
+    [Some("derive(Decodable) is deprecated in favor of derive(RustcDecodable)")]
     "Decodable" => decodable::expand_deriving_decodable,
 }
 
-#[inline] // because `name` is a compile-time constant
-fn warn_if_deprecated(ecx: &mut ExtCtxt<'_>, sp: Span, name: &str) {
-    if let Some(replacement) = match name {
-        "Encodable" => Some("RustcEncodable"),
-        "Decodable" => Some("RustcDecodable"),
-        _ => None,
-    } {
-        ecx.span_warn(sp,
-                      &format!("derive({}) is deprecated in favor of derive({})",
-                               name,
-                               replacement));
-    }
-}
-
 /// Construct a name for the inner type parameter that can't collide with any type parameters of
 /// the item. This is achieved by starting with a base and then concatenating the names of all
 /// other type parameters.