Support for groups of attributes in #pragma clang attribute

This commit enables pushing an empty #pragma clang attribute push, then adding
multiple attributes to it, then popping them all with #pragma clang attribute
pop, just like #pragma clang diagnostic. We still support the current way of
adding these, #pragma clang attribute push(__attribute__((...))), by treating it
like a combined push/attribute. This is needed to create macros like:

DO_SOMETHING_BEGIN(attr1, attr2, attr3)
// ...
DO_SOMETHING_END

rdar://45496947

Differential revision: https://reviews.llvm.org/D53621

llvm-svn: 345486

2 files changed, 84 insertions, 46 deletions

diff --git a/clang/lib/Parse/ParsePragma.cpp b/clang/lib/Parse/ParsePragma.cpp
index 26b363f280c..35072a739b9 100644
--- a/clang/lib/Parse/ParsePragma.cpp
+++ b/clang/lib/Parse/ParsePragma.cpp
@@ -1133,7 +1133,7 @@ bool Parser::HandlePragmaLoopHint(LoopHint &Hint) {
 
 namespace {
 struct PragmaAttributeInfo {
-  enum ActionType { Push, Pop };
+  enum ActionType { Push, Pop, Attribute };
   ParsedAttributes &Attributes;
   ActionType Action;
   ArrayRef<Token> Tokens;
@@ -1394,8 +1394,16 @@ void Parser::HandlePragmaAttribute() {
     return;
   }
   // Parse the actual attribute with its arguments.
-  assert(Info->Action == PragmaAttributeInfo::Push &&
-         "Unexpected #pragma attribute command");
+  assert(Info->Action == PragmaAttributeInfo::Push ||
+         Info->Action == PragmaAttributeInfo::Attribute &&
+             "Unexpected #pragma attribute command");
+
+  if (Info->Action == PragmaAttributeInfo::Push && Info->Tokens.empty()) {
+    ConsumeAnnotationToken();
+    Actions.ActOnPragmaAttributeEmptyPush(PragmaLoc);
+    return;
+  }
+
   PP.EnterTokenStream(Info->Tokens, /*DisableMacroExpansion=*/false);
   ConsumeAnnotationToken();
 
@@ -1542,8 +1550,12 @@ void Parser::HandlePragmaAttribute() {
   // Consume the eof terminator token.
   ConsumeToken();
 
-  Actions.ActOnPragmaAttributePush(Attribute, PragmaLoc,
-                                   std::move(SubjectMatchRules));
+  // Handle a mixed push/attribute by desurging to a push, then an attribute.
+  if (Info->Action == PragmaAttributeInfo::Push)
+    Actions.ActOnPragmaAttributeEmptyPush(PragmaLoc);
+
+  Actions.ActOnPragmaAttributeAttribute(Attribute, PragmaLoc,
+                                        std::move(SubjectMatchRules));
 }
 
 // #pragma GCC visibility comes in two variants:
@@ -3104,6 +3116,8 @@ void PragmaForceCUDAHostDeviceHandler::HandlePragma(
 /// The syntax is:
 /// \code
 ///  #pragma clang attribute push(attribute, subject-set)
+///  #pragma clang attribute push
+///  #pragma clang attribute (attribute, subject-set)
 ///  #pragma clang attribute pop
 /// \endcode
 ///
@@ -3122,25 +3136,33 @@ void PragmaAttributeHandler::HandlePragma(Preprocessor &PP,
   auto *Info = new (PP.getPreprocessorAllocator())
       PragmaAttributeInfo(AttributesForPragmaAttribute);
 
-  // Parse the 'push' or 'pop'.
-  if (Tok.isNot(tok::identifier)) {
-    PP.Diag(Tok.getLocation(), diag::err_pragma_attribute_expected_push_pop);
+  if (!Tok.isOneOf(tok::identifier, tok::l_paren)) {
+    PP.Diag(Tok.getLocation(),
+            diag::err_pragma_attribute_expected_push_pop_paren);
     return;
   }
-  const auto *II = Tok.getIdentifierInfo();
-  if (II->isStr("push"))
-    Info->Action = PragmaAttributeInfo::Push;
-  else if (II->isStr("pop"))
-    Info->Action = PragmaAttributeInfo::Pop;
+
+  // Determine what action this pragma clang attribute represents.
+  if (Tok.is(tok::l_paren))
+    Info->Action = PragmaAttributeInfo::Attribute;
   else {
-    PP.Diag(Tok.getLocation(), diag::err_pragma_attribute_invalid_argument)
-        << PP.getSpelling(Tok);
-    return;
+    const IdentifierInfo *II = Tok.getIdentifierInfo();
+    if (II->isStr("push"))
+      Info->Action = PragmaAttributeInfo::Push;
+    else if (II->isStr("pop"))
+      Info->Action = PragmaAttributeInfo::Pop;
+    else {
+      PP.Diag(Tok.getLocation(), diag::err_pragma_attribute_invalid_argument)
+          << PP.getSpelling(Tok);
+      return;
+    }
+
+    PP.Lex(Tok);
   }
-  PP.Lex(Tok);
 
   // Parse the actual attribute.
-  if (Info->Action == PragmaAttributeInfo::Push) {
+  if ((Info->Action == PragmaAttributeInfo::Push && Tok.isNot(tok::eod)) ||
+      Info->Action == PragmaAttributeInfo::Attribute) {
     if (Tok.isNot(tok::l_paren)) {
       PP.Diag(Tok.getLocation(), diag::err_expected) << tok::l_paren;
       return;
diff --git a/clang/lib/Sema/SemaAttr.cpp b/clang/lib/Sema/SemaAttr.cpp
index 8024e1a0515..f6ac9b44a83 100644
--- a/clang/lib/Sema/SemaAttr.cpp
+++ b/clang/lib/Sema/SemaAttr.cpp
@@ -520,9 +520,9 @@ attrMatcherRuleListToString(ArrayRef<attr::SubjectMatchRule> Rules) {
 
 } // end anonymous namespace
 
-void Sema::ActOnPragmaAttributePush(ParsedAttr &Attribute,
-                                    SourceLocation PragmaLoc,
-                                    attr::ParsedSubjectMatchRuleSet Rules) {
+void Sema::ActOnPragmaAttributeAttribute(
+    ParsedAttr &Attribute, SourceLocation PragmaLoc,
+    attr::ParsedSubjectMatchRuleSet Rules) {
   SmallVector<attr::SubjectMatchRule, 4> SubjectMatchRules;
   // Gather the subject match rules that are supported by the attribute.
   SmallVector<std::pair<attr::SubjectMatchRule, bool>, 4>
@@ -622,48 +622,64 @@ void Sema::ActOnPragmaAttributePush(ParsedAttr &Attribute,
     Diagnostic << attrMatcherRuleListToString(ExtraRules);
   }
 
-  PragmaAttributeStack.push_back(
+  if (PragmaAttributeStack.empty()) {
+    Diag(PragmaLoc, diag::err_pragma_attr_attr_no_push);
+    return;
+  }
+
+  PragmaAttributeStack.back().Entries.push_back(
       {PragmaLoc, &Attribute, std::move(SubjectMatchRules), /*IsUsed=*/false});
 }
 
+void Sema::ActOnPragmaAttributeEmptyPush(SourceLocation PragmaLoc) {
+  PragmaAttributeStack.emplace_back();
+  PragmaAttributeStack.back().Loc = PragmaLoc;
+}
+
 void Sema::ActOnPragmaAttributePop(SourceLocation PragmaLoc) {
   if (PragmaAttributeStack.empty()) {
     Diag(PragmaLoc, diag::err_pragma_attribute_stack_mismatch);
     return;
   }
-  const PragmaAttributeEntry &Entry = PragmaAttributeStack.back();
-  if (!Entry.IsUsed) {
-    assert(Entry.Attribute && "Expected an attribute");
-    Diag(Entry.Attribute->getLoc(), diag::warn_pragma_attribute_unused)
-        << Entry.Attribute->getName();
-    Diag(PragmaLoc, diag::note_pragma_attribute_region_ends_here);
+
+  for (const PragmaAttributeEntry &Entry :
+       PragmaAttributeStack.back().Entries) {
+    if (!Entry.IsUsed) {
+      assert(Entry.Attribute && "Expected an attribute");
+      Diag(Entry.Attribute->getLoc(), diag::warn_pragma_attribute_unused)
+          << Entry.Attribute->getName();
+      Diag(PragmaLoc, diag::note_pragma_attribute_region_ends_here);
+    }
   }
+
   PragmaAttributeStack.pop_back();
 }
 
 void Sema::AddPragmaAttributes(Scope *S, Decl *D) {
   if (PragmaAttributeStack.empty())
     return;
-  for (auto &Entry : PragmaAttributeStack) {
-    ParsedAttr *Attribute = Entry.Attribute;
-    assert(Attribute && "Expected an attribute");
-
-    // Ensure that the attribute can be applied to the given declaration.
-    bool Applies = false;
-    for (const auto &Rule : Entry.MatchRules) {
-      if (Attribute->appliesToDecl(D, Rule)) {
-        Applies = true;
-        break;
+  for (auto &Group : PragmaAttributeStack) {
+    for (auto &Entry : Group.Entries) {
+      ParsedAttr *Attribute = Entry.Attribute;
+      assert(Attribute && "Expected an attribute");
+
+      // Ensure that the attribute can be applied to the given declaration.
+      bool Applies = false;
+      for (const auto &Rule : Entry.MatchRules) {
+        if (Attribute->appliesToDecl(D, Rule)) {
+          Applies = true;
+          break;
+        }
       }
+      if (!Applies)
+        continue;
+      Entry.IsUsed = true;
+      PragmaAttributeCurrentTargetDecl = D;
+      ParsedAttributesView Attrs;
+      Attrs.addAtEnd(Attribute);
+      ProcessDeclAttributeList(S, D, Attrs);
+      PragmaAttributeCurrentTargetDecl = nullptr;
     }
-    if (!Applies)
-      continue;
-    Entry.IsUsed = true;
-    PragmaAttributeCurrentTargetDecl = D;
-    ParsedAttributesView Attrs;
-    Attrs.addAtEnd(Attribute);
-    ProcessDeclAttributeList(S, D, Attrs);
-    PragmaAttributeCurrentTargetDecl = nullptr;
   }
 }