tra created this revision.
tra added reviewers: rsmith, arphaman.
Herald added a subscriber: bixia.
tra requested review of this revision.
Herald added a project: clang.
The original intent of enforcing exact match between `apply_to` and the
attribute's was to
`ensure that the user will know what declarations receive the attribute. If the
compiler changes the set of allowed attributes in the future`.
https://reviews.llvm.org/D30009?id=88764#inline-260744
However, the exact match, as implemented now, is too conservative. E.g. it does
not allow using `apply_to=variables(is_global)` with an attribute which has
`SubjectList<[Var]>`.
Applying an attribute to a subset of the allowed subjects should also be
allowed.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D100136
Files:
clang/lib/Sema/SemaAttr.cpp
clang/test/Parser/pragma-attribute.cpp
Index: clang/test/Parser/pragma-attribute.cpp
===================================================================
--- clang/test/Parser/pragma-attribute.cpp
+++ clang/test/Parser/pragma-attribute.cpp
@@ -195,3 +195,12 @@
#pragma clang attribute pop
#pragma clang attribute push([[clang::uninitialized]], apply_to =
any(variable(is_parameter), variable(unless(is_parameter)))) // expected-error
{{attribute 'uninitialized' can't be applied to 'variable(is_parameter)', and
'variable(unless(is_parameter))'}}
#pragma clang attribute pop
+// We're allowed to apply attributes to subsets of allowed subjects.
+#pragma clang attribute push([[clang::no_destroy]], apply_to = variable)
+#pragma clang attribute pop
+#pragma clang attribute push([[clang::no_destroy]], apply_to =
variable(is_thread_local))
+#pragma clang attribute pop
+#pragma clang attribute push([[clang::no_destroy]], apply_to =
variable(is_global))
+#pragma clang attribute pop
+#pragma clang attribute push([[clang::no_destroy]], apply_to =
any(variable(is_parameter), variable(unless(is_parameter))))
+#pragma clang attribute pop
Index: clang/lib/Sema/SemaAttr.cpp
===================================================================
--- clang/lib/Sema/SemaAttr.cpp
+++ clang/lib/Sema/SemaAttr.cpp
@@ -875,12 +875,33 @@
}
Rules.clear();
} else {
- for (const auto &Rule : StrictSubjectMatchRuleSet) {
- if (Rules.erase(Rule.first)) {
+ // Each rule in Rules must be a strict subset of the attribute's
+ // SubjectMatch rules. I.e. we're allowed to use
+ // `apply_to=variables(is_global)` on an attrubute with SubjectList<[Var]>,
+ // but should not allow `apply_to=variables` on an attribute which has
+ // `SubjectList<[GlobalVar]>`.
+ for (const auto &StrictRule : StrictSubjectMatchRuleSet) {
+ // First, check for exact match.
+ if (Rules.erase(StrictRule.first)) {
// Add the rule to the set of attribute receivers only if it's
supported
// in the current language mode.
- if (Rule.second)
- SubjectMatchRules.push_back(Rule.first);
+ if (StrictRule.second)
+ SubjectMatchRules.push_back(StrictRule.first);
+ }
+ }
+ // Check remaining rules for subset matches.
+ auto RulesToCheck = Rules;
+ for (const auto &Rule : RulesToCheck) {
+ attr::SubjectMatchRule MatchRule = attr::SubjectMatchRule(Rule.first);
+ if (auto ParentRule = getParentAttrMatcherRule(MatchRule)) {
+ if (llvm::any_of(StrictSubjectMatchRuleSet,
+ [ParentRule](const auto &StrictRule) {
+ return StrictRule.first == *ParentRule &&
+ StrictRule.second; // IsEnabled
+ })) {
+ SubjectMatchRules.push_back(MatchRule);
+ Rules.erase(MatchRule);
+ }
}
}
}
Index: clang/test/Parser/pragma-attribute.cpp
===================================================================
--- clang/test/Parser/pragma-attribute.cpp
+++ clang/test/Parser/pragma-attribute.cpp
@@ -195,3 +195,12 @@
#pragma clang attribute pop
#pragma clang attribute push([[clang::uninitialized]], apply_to = any(variable(is_parameter), variable(unless(is_parameter)))) // expected-error {{attribute 'uninitialized' can't be applied to 'variable(is_parameter)', and 'variable(unless(is_parameter))'}}
#pragma clang attribute pop
+// We're allowed to apply attributes to subsets of allowed subjects.
+#pragma clang attribute push([[clang::no_destroy]], apply_to = variable)
+#pragma clang attribute pop
+#pragma clang attribute push([[clang::no_destroy]], apply_to = variable(is_thread_local))
+#pragma clang attribute pop
+#pragma clang attribute push([[clang::no_destroy]], apply_to = variable(is_global))
+#pragma clang attribute pop
+#pragma clang attribute push([[clang::no_destroy]], apply_to = any(variable(is_parameter), variable(unless(is_parameter))))
+#pragma clang attribute pop
Index: clang/lib/Sema/SemaAttr.cpp
===================================================================
--- clang/lib/Sema/SemaAttr.cpp
+++ clang/lib/Sema/SemaAttr.cpp
@@ -875,12 +875,33 @@
}
Rules.clear();
} else {
- for (const auto &Rule : StrictSubjectMatchRuleSet) {
- if (Rules.erase(Rule.first)) {
+ // Each rule in Rules must be a strict subset of the attribute's
+ // SubjectMatch rules. I.e. we're allowed to use
+ // `apply_to=variables(is_global)` on an attrubute with SubjectList<[Var]>,
+ // but should not allow `apply_to=variables` on an attribute which has
+ // `SubjectList<[GlobalVar]>`.
+ for (const auto &StrictRule : StrictSubjectMatchRuleSet) {
+ // First, check for exact match.
+ if (Rules.erase(StrictRule.first)) {
// Add the rule to the set of attribute receivers only if it's supported
// in the current language mode.
- if (Rule.second)
- SubjectMatchRules.push_back(Rule.first);
+ if (StrictRule.second)
+ SubjectMatchRules.push_back(StrictRule.first);
+ }
+ }
+ // Check remaining rules for subset matches.
+ auto RulesToCheck = Rules;
+ for (const auto &Rule : RulesToCheck) {
+ attr::SubjectMatchRule MatchRule = attr::SubjectMatchRule(Rule.first);
+ if (auto ParentRule = getParentAttrMatcherRule(MatchRule)) {
+ if (llvm::any_of(StrictSubjectMatchRuleSet,
+ [ParentRule](const auto &StrictRule) {
+ return StrictRule.first == *ParentRule &&
+ StrictRule.second; // IsEnabled
+ })) {
+ SubjectMatchRules.push_back(MatchRule);
+ Rules.erase(MatchRule);
+ }
}
}
}
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