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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 4695 : FeatureGate::check (AST::Crate &crate)
32 : {
33 4695 : auto &store = Features::EarlyFeatureGateStore::get ();
34 9394 : 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 4695 : visit (crate);
40 4695 : }
41 :
42 : void
43 4695 : FeatureGate::visit (AST::Crate &crate)
44 : {
45 4695 : AST::DefaultASTVisitor::visit (crate);
46 :
47 4700 : 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 16601 : for (const auto &attribute : crate.inner_attrs)
67 : {
68 11906 : check_no_core_attribute (attribute);
69 :
70 11906 : if (attribute.get_path ().as_string ()
71 11906 : == 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 4695 : }
78 :
79 : void
80 9008 : FeatureGate::gate (Feature::Name name, location_t loc,
81 : const std::string &error_msg)
82 : {
83 9008 : if (!features.valid_lang_features.count (name))
84 : {
85 19 : auto &feature = Feature::lookup (name);
86 19 : 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 9 : const char *fmt_str
101 : = "%s. add `#![feature(%s)]` to the crate attributes to enable.";
102 9 : rust_error_at (loc, ErrorCode::E0658, fmt_str, error_msg.c_str (),
103 9 : feature.as_string ().c_str ());
104 : }
105 : }
106 9008 : }
107 :
108 : void
109 1620 : FeatureGate::visit (AST::ExternBlock &block)
110 : {
111 1620 : if (block.has_abi ())
112 : {
113 1620 : const auto abi = block.get_abi ();
114 :
115 1620 : if (get_abi_from_string (abi) == ABI::INTRINSIC)
116 556 : gate (Feature::Name::INTRINSICS, block.get_locus (),
117 1112 : "intrinsics are subject to change");
118 1620 : }
119 1620 : AST::DefaultASTVisitor::visit (block);
120 1620 : }
121 :
122 : void
123 11906 : FeatureGate::check_no_core_attribute (const AST::Attribute &attribute)
124 : {
125 11906 : if (attribute.get_path ().as_string () == Values::Attributes::NO_CORE)
126 4696 : gate (Feature::Name::NO_CORE, attribute.get_locus (),
127 9392 : "no_core is experimental");
128 11906 : }
129 :
130 : void
131 17242 : FeatureGate::check_rustc_attri (const std::vector<AST::Attribute> &attributes)
132 : {
133 27343 : for (const AST::Attribute &attr : attributes)
134 : {
135 10101 : auto name = attr.get_path ().as_string ();
136 10101 : if (name.rfind ("rustc_", 0) == 0)
137 : {
138 270 : gate (Feature::Name::RUSTC_ATTRS, attr.get_locus (),
139 540 : "internal implementation detail");
140 : }
141 10101 : }
142 17242 : }
143 :
144 : void
145 8819 : FeatureGate::check_may_dangle_attribute (
146 : const std::vector<AST::Attribute> &attributes)
147 : {
148 8824 : 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 8819 : }
156 :
157 : void
158 26020 : FeatureGate::check_lang_item_attribute (
159 : const std::vector<AST::Attribute> &attributes)
160 : {
161 40899 : for (const AST::Attribute &attr : attributes)
162 : {
163 14879 : const auto &str_path = attr.get_path ().as_string ();
164 14879 : bool is_lang_item = str_path == Values::Attributes::LANG
165 3264 : && attr.has_attr_input ()
166 18143 : && attr.get_attr_input ().get_attr_input_type ()
167 14879 : == AST::AttrInput::AttrInputType::LITERAL;
168 :
169 3264 : if (is_lang_item)
170 3264 : gate (Feature::Name::LANG_ITEMS, attr.get_locus (),
171 6528 : "lang items are subject to change");
172 14879 : }
173 26020 : }
174 :
175 : void
176 19744 : FeatureGate::note_stability_attribute (
177 : const std::vector<AST::Attribute> &attributes)
178 : {
179 30017 : for (const AST::Attribute &attr : attributes)
180 : {
181 10273 : std::string attr_name = attr.get_path ().as_string ();
182 :
183 10273 : Stability stability;
184 :
185 10273 : if (attr_name == Values::Attributes::STABLE)
186 643 : stability = Stability::STABLE;
187 9630 : else if (attr_name == Values::Attributes::UNSTABLE)
188 100 : stability = Stability::UNSTABLE;
189 9530 : else if (attr_name == Values::Attributes::RUSTC_CONST_STABLE)
190 159 : stability = Stability::STABLE;
191 9371 : else if (attr_name == Values::Attributes::RUSTC_CONST_UNSTABLE)
192 8 : stability = Stability::UNSTABLE;
193 : else
194 9363 : continue;
195 :
196 910 : if (attr.empty_input ())
197 : // TODO: error?
198 0 : continue;
199 :
200 910 : auto &attr_input = attr.get_attr_input ();
201 910 : if (attr_input.get_attr_input_type ()
202 : != AST::AttrInput::AttrInputType::TOKEN_TREE)
203 : // TODO: error?
204 0 : continue;
205 :
206 910 : std::unique_ptr<AST::AttrInputMetaItemContainer> meta_item (
207 : static_cast<const AST::DelimTokenTree &> (attr_input)
208 910 : .parse_to_meta_item ());
209 :
210 2730 : for (auto &item : meta_item->get_items ())
211 : {
212 : // TODO: more thorough error checking?
213 : // ~only the standard libraries should ever exercise this
214 1820 : if (item->is_key_value_pair ())
215 : {
216 1820 : auto &pair = static_cast<const AST::MetaNameValueStr &> (*item);
217 1820 : if (pair.get_name ().as_string () == "feature")
218 910 : defined_lib_features.emplace (pair.get_value (), stability);
219 : }
220 : }
221 10273 : }
222 19744 : }
223 :
224 : void
225 979 : FeatureGate::visit (AST::MacroRulesDefinition &rules_def)
226 : {
227 979 : check_rustc_attri (rules_def.get_outer_attrs ());
228 979 : note_stability_attribute (rules_def.get_outer_attrs ());
229 979 : }
230 :
231 : void
232 18765 : FeatureGate::visit (AST::Function &function)
233 : {
234 18765 : if (!function.is_external ())
235 16263 : check_rustc_attri (function.get_outer_attrs ());
236 :
237 28868 : for (const AST::Attribute &attr : function.get_outer_attrs ())
238 : {
239 10103 : if (attr.get_path ().as_string () == "rustc_const_stable")
240 : {
241 159 : gate (Feature::Name::STAGED_API, attr.get_locus (),
242 318 : "stability attributes may not be used outside of the standard "
243 : "library");
244 : }
245 : }
246 :
247 18765 : check_lang_item_attribute (function.get_outer_attrs ());
248 :
249 18765 : note_stability_attribute (function.get_outer_attrs ());
250 :
251 18765 : AST::DefaultASTVisitor::visit (function);
252 18765 : }
253 :
254 : void
255 1 : FeatureGate::visit (AST::ExternalTypeItem &item)
256 : {
257 : // TODO(mxlol233): The gating needs a complete visiting chain to activate
258 : // `AST::ExternalTypeItem`.
259 1 : gate (Feature::Name::EXTERN_TYPES, item.get_locus (),
260 1 : "extern types are experimental");
261 1 : }
262 :
263 : void
264 4742 : FeatureGate::visit (AST::TraitImpl &impl)
265 : {
266 4742 : if (impl.is_exclam ())
267 6 : gate (Feature::Name::NEGATIVE_IMPLS, impl.get_locus (),
268 12 : "negative_impls are not yet implemented");
269 :
270 4742 : AST::DefaultASTVisitor::visit (impl);
271 4742 : }
272 :
273 : void
274 3899 : FeatureGate::visit (AST::Trait &trait)
275 : {
276 3899 : if (trait.is_auto ())
277 20 : gate (Feature::Name::OPTIN_BUILTIN_TRAITS, trait.get_locus (),
278 40 : "auto traits are experimental and possibly buggy");
279 3899 : check_lang_item_attribute (trait.get_outer_attrs ());
280 3899 : AST::DefaultASTVisitor::visit (trait);
281 3899 : }
282 :
283 : void
284 1 : FeatureGate::visit (AST::BoxExpr &expr)
285 : {
286 1 : gate (
287 : Feature::Name::BOX_SYNTAX, expr.get_locus (),
288 1 : "box expression syntax is experimental; you can call `Box::new` instead");
289 1 : AST::DefaultASTVisitor::visit (expr);
290 1 : }
291 :
292 : void
293 277 : FeatureGate::visit (AST::LifetimeParam &lifetime_param)
294 : {
295 277 : check_may_dangle_attribute (lifetime_param.get_outer_attrs ());
296 277 : AST::DefaultASTVisitor::visit (lifetime_param);
297 277 : }
298 :
299 : void
300 101 : FeatureGate::visit (AST::ConstGenericParam &const_param)
301 : {
302 101 : check_may_dangle_attribute (const_param.get_outer_attrs ());
303 101 : AST::DefaultASTVisitor::visit (const_param);
304 101 : }
305 :
306 : void
307 8441 : FeatureGate::visit (AST::TypeParam ¶m)
308 : {
309 8441 : check_may_dangle_attribute (param.get_outer_attrs ());
310 8441 : AST::DefaultASTVisitor::visit (param);
311 8441 : }
312 :
313 : void
314 1932 : FeatureGate::visit (AST::BorrowExpr &expr)
315 : {
316 1932 : if (expr.is_raw_borrow ())
317 5 : gate (Feature::Name::RAW_REF_OP, expr.get_locus (),
318 10 : "raw address of syntax is experimental");
319 1932 : }
320 :
321 : void
322 51 : FeatureGate::visit (AST::RangePattern &pattern)
323 : {
324 51 : if (pattern.get_range_kind () == AST::RangeKind::EXCLUDED)
325 20 : gate (Feature::Name::EXCLUSIVE_RANGE_PATTERN, pattern.get_locus (),
326 40 : "exclusive range pattern syntax is experimental");
327 51 : }
328 :
329 : void
330 14 : FeatureGate::visit (AST::UseTreeGlob &use)
331 : {
332 : // At the moment, UseTrees do not have outer attributes, but they should. we
333 : // need to eventually gate `#[prelude_import]` on use-trees based on the
334 : // #[feature(prelude_import)]
335 14 : }
336 :
337 : void
338 1602 : FeatureGate::visit (AST::StructStruct &struct_item)
339 : {
340 1602 : check_lang_item_attribute (struct_item.get_outer_attrs ());
341 1602 : AST::DefaultASTVisitor::visit (struct_item);
342 1602 : }
343 :
344 : void
345 738 : FeatureGate::visit (AST::TraitItemType &trait_item_type)
346 : {
347 738 : check_lang_item_attribute (trait_item_type.get_outer_attrs ());
348 738 : AST::DefaultASTVisitor::visit (trait_item_type);
349 738 : }
350 :
351 : void
352 553 : FeatureGate::visit (AST::Enum &enum_item)
353 : {
354 553 : check_lang_item_attribute (enum_item.get_outer_attrs ());
355 553 : AST::DefaultASTVisitor::visit (enum_item);
356 553 : }
357 :
358 : void
359 463 : FeatureGate::visit (AST::EnumItem &enum_variant)
360 : {
361 463 : check_lang_item_attribute (enum_variant.get_outer_attrs ());
362 463 : AST::DefaultASTVisitor::visit (enum_variant);
363 463 : }
364 :
365 : } // namespace Rust
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