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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 4770 : FeatureGate::check (AST::Crate &crate)
32 : {
33 4770 : auto &store = Features::EarlyFeatureGateStore::get ();
34 9544 : 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 4770 : visit (crate);
40 4770 : }
41 :
42 : void
43 4770 : FeatureGate::visit (AST::Crate &crate)
44 : {
45 4770 : AST::DefaultASTVisitor::visit (crate);
46 :
47 4775 : 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 16835 : for (const auto &attribute : crate.inner_attrs)
67 : {
68 12065 : check_no_core_attribute (attribute);
69 :
70 12065 : if (attribute.get_path ().as_string ()
71 12065 : == 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 4770 : }
78 :
79 : void
80 9186 : FeatureGate::gate (Feature::Name name, location_t loc,
81 : const std::string &error_msg)
82 : {
83 9186 : 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 9186 : }
107 :
108 : void
109 1657 : FeatureGate::visit (AST::ExternBlock &block)
110 : {
111 1657 : if (block.has_abi ())
112 : {
113 1656 : const auto abi = block.get_abi ();
114 :
115 1656 : if (get_abi_from_string (abi) == ABI::INTRINSIC)
116 570 : gate (Feature::Name::INTRINSICS, block.get_locus (),
117 1140 : "intrinsics are subject to change");
118 1656 : }
119 1657 : AST::DefaultASTVisitor::visit (block);
120 1657 : }
121 :
122 : void
123 12065 : FeatureGate::check_no_core_attribute (const AST::Attribute &attribute)
124 : {
125 12065 : if (attribute.get_path ().as_string () == Values::Attributes::NO_CORE)
126 4771 : gate (Feature::Name::NO_CORE, attribute.get_locus (),
127 9542 : "no_core is experimental");
128 12065 : }
129 :
130 : void
131 17462 : FeatureGate::check_rustc_attri (const std::vector<AST::Attribute> &attributes)
132 : {
133 27573 : for (const AST::Attribute &attr : attributes)
134 : {
135 10111 : auto name = attr.get_path ().as_string ();
136 10111 : if (name.rfind ("rustc_", 0) == 0)
137 : {
138 278 : gate (Feature::Name::RUSTC_ATTRS, attr.get_locus (),
139 556 : "internal implementation detail");
140 : }
141 10111 : }
142 17462 : }
143 :
144 : void
145 8978 : FeatureGate::check_may_dangle_attribute (
146 : const std::vector<AST::Attribute> &attributes)
147 : {
148 8983 : 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 8978 : }
156 :
157 : void
158 26441 : FeatureGate::check_lang_item_attribute (
159 : const std::vector<AST::Attribute> &attributes)
160 : {
161 41403 : for (const AST::Attribute &attr : attributes)
162 : {
163 14962 : const auto &str_path = attr.get_path ().as_string ();
164 14962 : bool is_lang_item = str_path == Values::Attributes::LANG
165 3332 : && attr.has_attr_input ()
166 18294 : && attr.get_attr_input ().get_attr_input_type ()
167 14962 : == AST::AttrInput::AttrInputType::LITERAL;
168 :
169 3332 : if (is_lang_item)
170 3332 : gate (Feature::Name::LANG_ITEMS, attr.get_locus (),
171 6664 : "lang items are subject to change");
172 14962 : }
173 26441 : }
174 :
175 : void
176 20007 : FeatureGate::note_stability_attribute (
177 : const std::vector<AST::Attribute> &attributes)
178 : {
179 30298 : for (const AST::Attribute &attr : attributes)
180 : {
181 10291 : std::string attr_name = attr.get_path ().as_string ();
182 :
183 10291 : Stability stability;
184 :
185 10291 : if (attr_name == Values::Attributes::STABLE)
186 643 : stability = Stability::STABLE;
187 9648 : else if (attr_name == Values::Attributes::UNSTABLE)
188 100 : stability = Stability::UNSTABLE;
189 9548 : else if (attr_name == Values::Attributes::RUSTC_CONST_STABLE)
190 167 : stability = Stability::STABLE;
191 9381 : else if (attr_name == Values::Attributes::RUSTC_CONST_UNSTABLE)
192 8 : stability = Stability::UNSTABLE;
193 : else
194 9373 : continue;
195 :
196 918 : if (attr.empty_input ())
197 : // TODO: error?
198 0 : continue;
199 :
200 918 : auto &attr_input = attr.get_attr_input ();
201 918 : if (attr_input.get_attr_input_type ()
202 : != AST::AttrInput::AttrInputType::TOKEN_TREE)
203 : // TODO: error?
204 0 : continue;
205 :
206 918 : std::unique_ptr<AST::AttrInputMetaItemContainer> meta_item (
207 : static_cast<const AST::DelimTokenTree &> (attr_input)
208 918 : .parse_to_meta_item ());
209 :
210 2754 : for (auto &item : meta_item->get_items ())
211 : {
212 : // TODO: more thorough error checking?
213 : // ~only the standard libraries should ever exercise this
214 1836 : if (item->is_key_value_pair ())
215 : {
216 1836 : auto &pair = static_cast<const AST::MetaNameValueStr &> (*item);
217 1836 : if (pair.get_name ().as_string () == "feature")
218 918 : defined_lib_features.emplace (pair.get_value (), stability);
219 : }
220 : }
221 10291 : }
222 20007 : }
223 :
224 : void
225 980 : FeatureGate::visit (AST::MacroRulesDefinition &rules_def)
226 : {
227 980 : check_rustc_attri (rules_def.get_outer_attrs ());
228 980 : note_stability_attribute (rules_def.get_outer_attrs ());
229 980 : }
230 :
231 : void
232 19027 : FeatureGate::visit (AST::Function &function)
233 : {
234 19027 : if (!function.is_external ())
235 16482 : check_rustc_attri (function.get_outer_attrs ());
236 :
237 29147 : for (const AST::Attribute &attr : function.get_outer_attrs ())
238 : {
239 10120 : if (attr.get_path ().as_string () == "rustc_const_stable")
240 : {
241 167 : gate (Feature::Name::STAGED_API, attr.get_locus (),
242 334 : "stability attributes may not be used outside of the standard "
243 : "library");
244 : }
245 : }
246 :
247 19027 : check_lang_item_attribute (function.get_outer_attrs ());
248 :
249 19027 : note_stability_attribute (function.get_outer_attrs ());
250 :
251 19027 : AST::DefaultASTVisitor::visit (function);
252 19027 : }
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 4812 : FeatureGate::visit (AST::TraitImpl &impl)
265 : {
266 4812 : if (impl.is_exclam ())
267 6 : gate (Feature::Name::NEGATIVE_IMPLS, impl.get_locus (),
268 12 : "negative_impls are not yet implemented");
269 :
270 4812 : AST::DefaultASTVisitor::visit (impl);
271 4812 : }
272 :
273 : void
274 3980 : FeatureGate::visit (AST::Trait &trait)
275 : {
276 3980 : 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 3980 : check_lang_item_attribute (trait.get_outer_attrs ());
280 3980 : AST::DefaultASTVisitor::visit (trait);
281 3980 : }
282 :
283 : void
284 4 : FeatureGate::visit (AST::BoxExpr &expr)
285 : {
286 4 : gate (
287 : Feature::Name::BOX_SYNTAX, expr.get_locus (),
288 4 : "box expression syntax is experimental; you can call `Box::new` instead");
289 4 : AST::DefaultASTVisitor::visit (expr);
290 4 : }
291 :
292 : void
293 267 : FeatureGate::visit (AST::LifetimeParam &lifetime_param)
294 : {
295 267 : check_may_dangle_attribute (lifetime_param.get_outer_attrs ());
296 267 : AST::DefaultASTVisitor::visit (lifetime_param);
297 267 : }
298 :
299 : void
300 103 : FeatureGate::visit (AST::ConstGenericParam &const_param)
301 : {
302 103 : check_may_dangle_attribute (const_param.get_outer_attrs ());
303 103 : AST::DefaultASTVisitor::visit (const_param);
304 103 : }
305 :
306 : void
307 8608 : FeatureGate::visit (AST::TypeParam ¶m)
308 : {
309 8608 : check_may_dangle_attribute (param.get_outer_attrs ());
310 8608 : AST::DefaultASTVisitor::visit (param);
311 8608 : }
312 :
313 : void
314 2003 : FeatureGate::visit (AST::BorrowExpr &expr)
315 : {
316 2003 : 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 2003 : }
320 :
321 : void
322 55 : FeatureGate::visit (AST::RangePattern &pattern)
323 : {
324 55 : if (pattern.get_range_kind () == AST::RangeKind::EXCLUDED)
325 22 : gate (Feature::Name::EXCLUSIVE_RANGE_PATTERN, pattern.get_locus (),
326 44 : "exclusive range pattern syntax is experimental");
327 55 : }
328 :
329 : void
330 16 : 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 16 : }
336 :
337 : void
338 1668 : FeatureGate::visit (AST::StructStruct &struct_item)
339 : {
340 1668 : check_lang_item_attribute (struct_item.get_outer_attrs ());
341 1668 : AST::DefaultASTVisitor::visit (struct_item);
342 1668 : }
343 :
344 : void
345 741 : FeatureGate::visit (AST::TraitItemType &trait_item_type)
346 : {
347 741 : check_lang_item_attribute (trait_item_type.get_outer_attrs ());
348 741 : AST::DefaultASTVisitor::visit (trait_item_type);
349 741 : }
350 :
351 : void
352 557 : FeatureGate::visit (AST::Enum &enum_item)
353 : {
354 557 : check_lang_item_attribute (enum_item.get_outer_attrs ());
355 557 : AST::DefaultASTVisitor::visit (enum_item);
356 557 : }
357 :
358 : void
359 468 : FeatureGate::visit (AST::EnumItem &enum_variant)
360 : {
361 468 : check_lang_item_attribute (enum_variant.get_outer_attrs ());
362 468 : AST::DefaultASTVisitor::visit (enum_variant);
363 468 : }
364 :
365 : } // namespace Rust
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