Add support for GCC's '__auto_type' extension, per the GCC manual:

https://gcc.gnu.org/onlinedocs/gcc/Typeof.html

Differences from the GCC extension:
 * __auto_type is also permitted in C++ (but only in places where
   it could appear in C), allowing its use in headers that might
   be shared across C and C++, or used from C++98
 * __auto_type can be combined with a declarator, as with C++ auto
   (for instance, "__auto_type *p")
 * multiple variables can be declared in a single __auto_type
   declaration, with the C++ semantics (the deduced type must be
   the same in each case)

This patch also adds a missing restriction on applying typeof to
a bit-field, which GCC has historically rejected in C (due to
lack of clarity as to whether the operand should be promoted).
The same restriction also applies to __auto_type in C (in both
GCC and Clang).

This also fixes PR25449.

Patch by Nicholas Allegra!

llvm-svn: 252690

3 files changed, 10 insertions, 0 deletions

diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 51b4eee24e6..cf3189a91a9 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -3138,6 +3138,11 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
                                            PrevSpec, DiagID, Policy);
       isStorageClass = true;
       break;
+    case tok::kw___auto_type:
+      Diag(Tok, diag::ext_auto_type);
+      isInvalid = DS.SetTypeSpecType(DeclSpec::TST_auto_type, Loc, PrevSpec,
+                                     DiagID, Policy);
+      break;
     case tok::kw_register:
       isInvalid = DS.SetStorageClassSpec(Actions, DeclSpec::SCS_register, Loc,
                                          PrevSpec, DiagID, Policy);
@@ -4440,6 +4445,7 @@ bool Parser::isDeclarationSpecifier(bool DisambiguatingWithExpression) {
   case tok::kw___private_extern__:
   case tok::kw_static:
   case tok::kw_auto:
+  case tok::kw___auto_type:
   case tok::kw_register:
   case tok::kw___thread:
   case tok::kw_thread_local:
diff --git a/clang/lib/Parse/ParseObjc.cpp b/clang/lib/Parse/ParseObjc.cpp
index 4ac8f42f136..698c38f9c31 100644
--- a/clang/lib/Parse/ParseObjc.cpp
+++ b/clang/lib/Parse/ParseObjc.cpp
@@ -1127,6 +1127,7 @@ IdentifierInfo *Parser::ParseObjCSelectorPiece(SourceLocation &SelectorLoc) {
   case tok::kw__Bool:
   case tok::kw__Complex:
   case tok::kw___alignof:
+  case tok::kw___auto_type:
     IdentifierInfo *II = Tok.getIdentifierInfo();
     SelectorLoc = ConsumeToken();
     return II;
diff --git a/clang/lib/Parse/ParseTentative.cpp b/clang/lib/Parse/ParseTentative.cpp
index 9d2a2b931e8..6fbcfd9bd21 100644
--- a/clang/lib/Parse/ParseTentative.cpp
+++ b/clang/lib/Parse/ParseTentative.cpp
@@ -1089,6 +1089,7 @@ public:
 /// [GNU]     typeof-specifier
 /// [GNU]     '_Complex'
 /// [C++11]   'auto'
+/// [GNU]     '__auto_type'
 /// [C++11]   'decltype' ( expression )
 /// [C++1y]   'decltype' ( 'auto' )
 ///
@@ -1262,6 +1263,7 @@ Parser::isCXXDeclarationSpecifier(Parser::TPResult BracedCastResult,
   case tok::kw_restrict:
   case tok::kw__Complex:
   case tok::kw___attribute:
+  case tok::kw___auto_type:
     return TPResult::True;
 
     // Microsoft
@@ -1515,6 +1517,7 @@ bool Parser::isCXXDeclarationSpecifierAType() {
   case tok::kw_double:
   case tok::kw_void:
   case tok::kw___unknown_anytype:
+  case tok::kw___auto_type:
     return true;
 
   case tok::kw_auto: