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1 : // Copyright (C) 2020-2026 Free Software Foundation, Inc.
2 :
3 : // This file is part of GCC.
4 :
5 : // GCC is free software; you can redistribute it and/or modify it under
6 : // the terms of the GNU General Public License as published by the Free
7 : // Software Foundation; either version 3, or (at your option) any later
8 : // version.
9 :
10 : // GCC is distributed in the hope that it will be useful, but WITHOUT ANY
11 : // WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 : // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 : // for more details.
14 :
15 : // You should have received a copy of the GNU General Public License
16 : // along with GCC; see the file COPYING3. If not see
17 : // <http://www.gnu.org/licenses/>.
18 :
19 : #include "rust-feature-gate.h"
20 : #include "rust-abi.h"
21 : #include "rust-attribute-values.h"
22 : #include "rust-attributes.h"
23 : #include "rust-ast-visitor.h"
24 : #include "rust-feature.h"
25 : #include "rust-ast-full.h"
26 : #include "rust-feature-store.h"
27 :
28 : namespace Rust {
29 :
30 : void
31 4683 : FeatureGate::check (AST::Crate &crate)
32 : {
33 4683 : auto &store = Features::EarlyFeatureGateStore::get ();
34 9370 : while (store.has_error ())
35 : {
36 4 : auto pair = store.get_error ();
37 4 : gate (pair.first, pair.second.locus, pair.second.message);
38 4 : }
39 4683 : visit (crate);
40 4683 : }
41 :
42 : void
43 4683 : FeatureGate::visit (AST::Crate &crate)
44 : {
45 4683 : AST::DefaultASTVisitor::visit (crate);
46 :
47 4688 : for (auto &ent : features.valid_lib_features)
48 : {
49 5 : const std::string &feature = ent.first;
50 5 : location_t locus = ent.second;
51 :
52 : // rustc treats these as valid,
53 : // but apparently has special handling for them
54 5 : if (feature == "libc" || feature == "test")
55 0 : continue;
56 :
57 5 : if (defined_lib_features.find (feature) != defined_lib_features.end ())
58 : {
59 : // TODO: emit warning if stable
60 0 : continue;
61 : }
62 :
63 5 : rust_error_at (locus, ErrorCode::E0635, "unknown feature %qs",
64 : feature.c_str ());
65 : }
66 16544 : for (const auto &attribute : crate.inner_attrs)
67 : {
68 11861 : check_no_core_attribute (attribute);
69 :
70 11861 : if (attribute.get_path ().as_string ()
71 11861 : == Values::Attributes::COMPILER_BUILTINS)
72 1 : gate (Feature::Name::COMPILER_BUILTINS, attribute.get_locus (),
73 2 : "the #[compiler_builtins] attribute is used to identify the "
74 : "compiler_builtins crate which contains compiler-rt intrinsics "
75 : "and will never be stable");
76 : }
77 4683 : }
78 :
79 : void
80 8833 : FeatureGate::gate (Feature::Name name, location_t loc,
81 : const std::string &error_msg)
82 : {
83 8833 : if (!features.valid_lang_features.count (name))
84 : {
85 17 : auto &feature = Feature::lookup (name);
86 17 : if (auto issue = feature.issue ())
87 : {
88 10 : auto issue_number = issue.value ();
89 10 : const char *fmt_str
90 : = "%s. see issue %u "
91 : "<https://github.com/rust-lang/rust/issues/%u> for more "
92 : "information. add `#![feature(%s)]` to the crate attributes to "
93 : "enable.";
94 10 : rust_error_at (loc, ErrorCode::E0658, fmt_str, error_msg.c_str (),
95 : issue_number, issue_number,
96 10 : feature.as_string ().c_str ());
97 : }
98 : else
99 : {
100 7 : const char *fmt_str
101 : = "%s. add `#![feature(%s)]` to the crate attributes to enable.";
102 7 : rust_error_at (loc, ErrorCode::E0658, fmt_str, error_msg.c_str (),
103 7 : feature.as_string ().c_str ());
104 : }
105 : }
106 8833 : }
107 :
108 : void
109 1617 : FeatureGate::visit (AST::ExternBlock &block)
110 : {
111 1617 : if (block.has_abi ())
112 : {
113 1617 : const auto abi = block.get_abi ();
114 :
115 1617 : if (get_abi_from_string (abi) == ABI::INTRINSIC)
116 555 : gate (Feature::Name::INTRINSICS, block.get_locus (),
117 1110 : "intrinsics are subject to change");
118 1617 : }
119 1617 : AST::DefaultASTVisitor::visit (block);
120 1617 : }
121 :
122 : void
123 11861 : FeatureGate::check_no_core_attribute (const AST::Attribute &attribute)
124 : {
125 11861 : if (attribute.get_path ().as_string () == Values::Attributes::NO_CORE)
126 4684 : gate (Feature::Name::NO_CORE, attribute.get_locus (),
127 9368 : "no_core is experimental");
128 11861 : }
129 :
130 : void
131 17223 : FeatureGate::check_rustc_attri (const std::vector<AST::Attribute> &attributes)
132 : {
133 27322 : for (const AST::Attribute &attr : attributes)
134 : {
135 10099 : auto name = attr.get_path ().as_string ();
136 10099 : if (name.rfind ("rustc_", 0) == 0)
137 : {
138 269 : gate (Feature::Name::RUSTC_ATTRS, attr.get_locus (),
139 538 : "internal implementation detail");
140 : }
141 10099 : }
142 17223 : }
143 :
144 : void
145 8813 : FeatureGate::check_may_dangle_attribute (
146 : const std::vector<AST::Attribute> &attributes)
147 : {
148 8818 : for (const AST::Attribute &attr : attributes)
149 : {
150 5 : if (attr.get_path ().as_string () == Values::Attributes::MAY_DANGLE)
151 5 : gate (Feature::Name::DROPCK_EYEPATCH, attr.get_locus (),
152 10 : "`may_dangle` has unstable semantics and may be removed in the "
153 : "future");
154 : }
155 8813 : }
156 :
157 : void
158 25996 : FeatureGate::check_lang_item_attribute (
159 : const std::vector<AST::Attribute> &attributes)
160 : {
161 40872 : for (const AST::Attribute &attr : attributes)
162 : {
163 14876 : const auto &str_path = attr.get_path ().as_string ();
164 14876 : bool is_lang_item = str_path == Values::Attributes::LANG
165 3262 : && attr.has_attr_input ()
166 18138 : && attr.get_attr_input ().get_attr_input_type ()
167 14876 : == AST::AttrInput::AttrInputType::LITERAL;
168 :
169 3262 : if (is_lang_item)
170 3262 : gate (Feature::Name::LANG_ITEMS, attr.get_locus (),
171 6524 : "lang items are subject to change");
172 14876 : }
173 25996 : }
174 :
175 : void
176 19722 : FeatureGate::note_stability_attribute (
177 : const std::vector<AST::Attribute> &attributes)
178 : {
179 29992 : for (const AST::Attribute &attr : attributes)
180 : {
181 10270 : std::string attr_name = attr.get_path ().as_string ();
182 :
183 10270 : Stability stability;
184 :
185 10270 : if (attr_name == Values::Attributes::STABLE)
186 643 : stability = Stability::STABLE;
187 9627 : else if (attr_name == Values::Attributes::UNSTABLE)
188 100 : stability = Stability::UNSTABLE;
189 9527 : else if (attr_name == Values::Attributes::RUSTC_CONST_STABLE)
190 158 : stability = Stability::STABLE;
191 9369 : else if (attr_name == Values::Attributes::RUSTC_CONST_UNSTABLE)
192 8 : stability = Stability::UNSTABLE;
193 : else
194 9361 : continue;
195 :
196 909 : if (attr.empty_input ())
197 : // TODO: error?
198 0 : continue;
199 :
200 909 : auto &attr_input = attr.get_attr_input ();
201 909 : if (attr_input.get_attr_input_type ()
202 : != AST::AttrInput::AttrInputType::TOKEN_TREE)
203 : // TODO: error?
204 0 : continue;
205 :
206 909 : std::unique_ptr<AST::AttrInputMetaItemContainer> meta_item (
207 : static_cast<const AST::DelimTokenTree &> (attr_input)
208 909 : .parse_to_meta_item ());
209 :
210 2727 : for (auto &item : meta_item->get_items ())
211 : {
212 : // TODO: more thorough error checking?
213 : // ~only the standard libraries should ever exercise this
214 1818 : if (item->is_key_value_pair ())
215 : {
216 1818 : auto &pair = static_cast<const AST::MetaNameValueStr &> (*item);
217 1818 : if (pair.get_name ().as_string () == "feature")
218 909 : defined_lib_features.emplace (pair.get_value (), stability);
219 : }
220 : }
221 10270 : }
222 19722 : }
223 :
224 : void
225 976 : FeatureGate::visit (AST::MacroRulesDefinition &rules_def)
226 : {
227 976 : check_rustc_attri (rules_def.get_outer_attrs ());
228 976 : note_stability_attribute (rules_def.get_outer_attrs ());
229 976 : }
230 :
231 : void
232 18746 : FeatureGate::visit (AST::Function &function)
233 : {
234 18746 : if (!function.is_external ())
235 16247 : check_rustc_attri (function.get_outer_attrs ());
236 :
237 18746 : check_lang_item_attribute (function.get_outer_attrs ());
238 :
239 18746 : note_stability_attribute (function.get_outer_attrs ());
240 :
241 18746 : AST::DefaultASTVisitor::visit (function);
242 18746 : }
243 :
244 : void
245 1 : FeatureGate::visit (AST::ExternalTypeItem &item)
246 : {
247 : // TODO(mxlol233): The gating needs a complete visiting chain to activate
248 : // `AST::ExternalTypeItem`.
249 1 : gate (Feature::Name::EXTERN_TYPES, item.get_locus (),
250 1 : "extern types are experimental");
251 1 : }
252 :
253 : void
254 4742 : FeatureGate::visit (AST::TraitImpl &impl)
255 : {
256 4742 : if (impl.is_exclam ())
257 6 : gate (Feature::Name::NEGATIVE_IMPLS, impl.get_locus (),
258 12 : "negative_impls are not yet implemented");
259 :
260 4742 : AST::DefaultASTVisitor::visit (impl);
261 4742 : }
262 :
263 : void
264 3895 : FeatureGate::visit (AST::Trait &trait)
265 : {
266 3895 : if (trait.is_auto ())
267 20 : gate (Feature::Name::OPTIN_BUILTIN_TRAITS, trait.get_locus (),
268 40 : "auto traits are experimental and possibly buggy");
269 3895 : check_lang_item_attribute (trait.get_outer_attrs ());
270 3895 : AST::DefaultASTVisitor::visit (trait);
271 3895 : }
272 :
273 : void
274 1 : FeatureGate::visit (AST::BoxExpr &expr)
275 : {
276 1 : gate (
277 : Feature::Name::BOX_SYNTAX, expr.get_locus (),
278 1 : "box expression syntax is experimental; you can call `Box::new` instead");
279 1 : AST::DefaultASTVisitor::visit (expr);
280 1 : }
281 :
282 : void
283 277 : FeatureGate::visit (AST::LifetimeParam &lifetime_param)
284 : {
285 277 : check_may_dangle_attribute (lifetime_param.get_outer_attrs ());
286 277 : AST::DefaultASTVisitor::visit (lifetime_param);
287 277 : }
288 :
289 : void
290 100 : FeatureGate::visit (AST::ConstGenericParam &const_param)
291 : {
292 100 : check_may_dangle_attribute (const_param.get_outer_attrs ());
293 100 : AST::DefaultASTVisitor::visit (const_param);
294 100 : }
295 :
296 : void
297 8436 : FeatureGate::visit (AST::TypeParam ¶m)
298 : {
299 8436 : check_may_dangle_attribute (param.get_outer_attrs ());
300 8436 : AST::DefaultASTVisitor::visit (param);
301 8436 : }
302 :
303 : void
304 1929 : FeatureGate::visit (AST::BorrowExpr &expr)
305 : {
306 1929 : if (expr.is_raw_borrow ())
307 5 : gate (Feature::Name::RAW_REF_OP, expr.get_locus (),
308 10 : "raw address of syntax is experimental");
309 1929 : }
310 :
311 : void
312 51 : FeatureGate::visit (AST::RangePattern &pattern)
313 : {
314 51 : if (pattern.get_range_kind () == AST::RangeKind::EXCLUDED)
315 20 : gate (Feature::Name::EXCLUSIVE_RANGE_PATTERN, pattern.get_locus (),
316 40 : "exclusive range pattern syntax is experimental");
317 51 : }
318 :
319 : void
320 14 : FeatureGate::visit (AST::UseTreeGlob &use)
321 : {
322 : // At the moment, UseTrees do not have outer attributes, but they should. we
323 : // need to eventually gate `#[prelude_import]` on use-trees based on the
324 : // #[feature(prelude_import)]
325 14 : }
326 :
327 : void
328 1601 : FeatureGate::visit (AST::StructStruct &struct_item)
329 : {
330 1601 : check_lang_item_attribute (struct_item.get_outer_attrs ());
331 1601 : AST::DefaultASTVisitor::visit (struct_item);
332 1601 : }
333 :
334 : void
335 738 : FeatureGate::visit (AST::TraitItemType &trait_item_type)
336 : {
337 738 : check_lang_item_attribute (trait_item_type.get_outer_attrs ());
338 738 : AST::DefaultASTVisitor::visit (trait_item_type);
339 738 : }
340 :
341 : void
342 553 : FeatureGate::visit (AST::Enum &enum_item)
343 : {
344 553 : check_lang_item_attribute (enum_item.get_outer_attrs ());
345 553 : AST::DefaultASTVisitor::visit (enum_item);
346 553 : }
347 :
348 : void
349 463 : FeatureGate::visit (AST::EnumItem &enum_variant)
350 : {
351 463 : check_lang_item_attribute (enum_variant.get_outer_attrs ());
352 463 : AST::DefaultASTVisitor::visit (enum_variant);
353 463 : }
354 :
355 : } // namespace Rust
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