[Clang] Support multiple attributes in a single pragma

This adds support for multiple attributes in `#pragma clang attribute push`, for example:

```
```
or
```
```

Related attributes can now be applied with a single pragma, which makes it harder for developers to make an accidental error later when editing the code.

rdar://78269653

Differential Revision: https://reviews.llvm.org/D121283

1 files changed, 3 insertions, 1 deletions

diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 44a05ee..135b2df 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -600,6 +600,8 @@ unsigned Parser::ParseClangAttributeArgs(
 bool Parser::ParseMicrosoftDeclSpecArgs(IdentifierInfo *AttrName,
                                         SourceLocation AttrNameLoc,
                                         ParsedAttributes &Attrs) {
+  unsigned ExistingAttrs = Attrs.size();
+
   // If the attribute isn't known, we will not attempt to parse any
   // arguments.
   if (!hasAttribute(AttrSyntax::Declspec, nullptr, AttrName,
@@ -732,7 +734,7 @@ bool Parser::ParseMicrosoftDeclSpecArgs(IdentifierInfo *AttrName,
 
   // If this attribute's args were parsed, and it was expected to have
   // arguments but none were provided, emit a diagnostic.
-  if (!Attrs.empty() && Attrs.begin()->getMaxArgs() && !NumArgs) {
+  if (ExistingAttrs < Attrs.size() && Attrs.back().getMaxArgs() && !NumArgs) {
     Diag(OpenParenLoc, diag::err_attribute_requires_arguments) << AttrName;
     return false;
   }