Revert "[C2X] N3007 Type inference for object definitions"

This reverts commit 5d78b78. Reverting due to the failure found by: https://lab.llvm.org/buildbot/#/builders/245/builds/14999

Author: AaronBallman

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -240,10 +240,6 @@ def ext_imaginary_constant : Extension<
  "imaginary constants are a GNU extension">, InGroup<GNUImaginaryConstant>;
 def ext_integer_complex : Extension<
  "complex integer types are a GNU extension">, InGroup<GNUComplexInteger>;
-def ext_c23_auto_non_plain_identifier : Extension<
- "type inference of a declaration other than a plain identifier with optional "
- "trailing attributes is a Clang extension">,
- InGroup<DiagGroup<"auto-decl-extensions">>;
 
 def err_invalid_saturation_spec : Error<"'_Sat' specifier is only valid on "
  "'_Fract' or '_Accum', not '%0'">;
@@ -2392,8 +2388,7 @@ def err_auto_not_allowed : Error<
  "|in conversion function type|here|in lambda parameter"
  "|in type allocated by 'new'|in K&R-style function parameter"
  "|in template parameter|in friend declaration|in function prototype that is "
- "not a function declaration|in requires expression parameter"
- "|in array declaration}1">;
+ "not a function declaration|in requires expression parameter}1">;
 def err_dependent_deduced_tst : Error<
  "typename specifier refers to "
  "%select{class template|function template|variable template|alias template|"
@@ -2466,8 +2461,7 @@ def err_implied_std_initializer_list_not_found : Error<
 def err_malformed_std_initializer_list : Error<
  "std::initializer_list must be a class template with a single type parameter">;
 def err_auto_init_list_from_c : Error<
- "cannot use %select{'auto'|<ERROR>|'__auto_type'}0 with "
- "%select{initializer list|array}1 in C">;
+ "cannot use __auto_type with initializer list in C">;
 def err_auto_bitfield : Error<
  "cannot pass bit-field as __auto_type initializer in C">;
 
@@ -6670,8 +6664,8 @@ def err_func_def_incomplete_result : Error<
 def err_atomic_specifier_bad_type
  : Error<"_Atomic cannot be applied to "
  "%select{incomplete |array |function |reference |atomic |qualified "
- "|sizeless ||integer |}0type "
- "%1 %select{|||||||which is not trivially copyable||in C23}0">;
+ "|sizeless ||integer }0type "
+ "%1 %select{|||||||which is not trivially copyable|}0">;
 def warn_atomic_member_access : Warning<
  "accessing a member of an atomic structure or union is undefined behavior">,
  InGroup<DiagGroup<"atomic-access">>, DefaultError;

clang/lib/Parse/ParseDecl.cpp

@@ -4038,7 +4038,7 @@ void Parser::ParseDeclarationSpecifiers(
  isStorageClass = true;
  break;
  case tok::kw_auto:
- if (getLangOpts().CPlusPlus11 || getLangOpts().C23) {
+ if (getLangOpts().CPlusPlus11) {
  if (isKnownToBeTypeSpecifier(GetLookAheadToken(1))) {
  isInvalid = DS.SetStorageClassSpec(Actions, DeclSpec::SCS_auto, Loc,
  PrevSpec, DiagID, Policy);

clang/lib/Sema/DeclSpec.cpp

@@ -1375,9 +1375,8 @@ void DeclSpec::Finish(Sema &S, const PrintingPolicy &Policy) {
  StorageClassSpecLoc = SourceLocation();
  }
  // Diagnose if we've recovered from an ill-formed 'auto' storage class
- // specifier in a pre-C++11 dialect of C++ or in a pre-C23 dialect of C.
- if (!S.getLangOpts().CPlusPlus11 && !S.getLangOpts().C23 &&
- TypeSpecType == TST_auto)
+ // specifier in a pre-C++11 dialect of C++.
+ if (!S.getLangOpts().CPlusPlus11 && TypeSpecType == TST_auto)
  S.Diag(TSTLoc, diag::ext_auto_type_specifier);
  if (S.getLangOpts().CPlusPlus && !S.getLangOpts().CPlusPlus11 &&
  StorageClassSpec == SCS_auto)

clang/lib/Sema/SemaDecl.cpp

@@ -12863,15 +12863,6 @@ QualType Sema::deduceVarTypeFromInitializer(VarDecl *VDecl,
  DeducedType *Deduced = Type->getContainedDeducedType();
  assert(Deduced && "deduceVarTypeFromInitializer for non-deduced type");
 
- // Diagnose auto array declarations in C23, unless it's a supported extension.
- if (getLangOpts().C23 && Type->isArrayType() &&
- !isa_and_present<StringLiteral, InitListExpr>(Init)) {
- Diag(Range.getBegin(), diag::err_auto_not_allowed)
- << (int)Deduced->getContainedAutoType()->getKeyword()
- << /*in array decl*/ 23 << Range;
- return QualType();
- }
-
  // C++11 [dcl.spec.auto]p3
  if (!Init) {
  assert(VDecl && "no init for init capture deduction?");

clang/lib/Sema/SemaTemplateDeduction.cpp

@@ -4842,25 +4842,9 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *Init, QualType &Result,
  return TDK_Success;
  }
 
- // Make sure that we treat 'char[]' equaly as 'char*' in C23 mode.
- auto *String = dyn_cast<StringLiteral>(Init);
- if (getLangOpts().C23 && String && Type.getType()->isArrayType()) {
- Diag(Type.getBeginLoc(), diag::ext_c23_auto_non_plain_identifier);
- TypeLoc TL = TypeLoc(Init->getType(), Type.getOpaqueData());
- Result = SubstituteDeducedTypeTransform(*this, DependentResult).Apply(TL);
- assert(!Result.isNull() && "substituting DependentTy can't fail");
- return TDK_Success;
- }
-
- // Emit a warning if 'auto*' is used in pedantic and in C23 mode.
- if (getLangOpts().C23 && Type.getType()->isPointerType()) {
- Diag(Type.getBeginLoc(), diag::ext_c23_auto_non_plain_identifier);
- }
-
  auto *InitList = dyn_cast<InitListExpr>(Init);
  if (!getLangOpts().CPlusPlus && InitList) {
- Diag(Init->getBeginLoc(), diag::err_auto_init_list_from_c)
- << (int)AT->getKeyword() << getLangOpts().C23;
+ Diag(Init->getBeginLoc(), diag::err_auto_init_list_from_c);
  return TDK_AlreadyDiagnosed;
  }
 

clang/lib/Sema/SemaType.cpp

@@ -9880,14 +9880,11 @@ QualType Sema::BuildAtomicType(QualType T, SourceLocation Loc) {
  DisallowedKind = 5;
  else if (T->isSizelessType())
  DisallowedKind = 6;
- else if (!T.isTriviallyCopyableType(Context) && getLangOpts().CPlusPlus)
+ else if (!T.isTriviallyCopyableType(Context))
  // Some other non-trivially-copyable type (probably a C++ class)
  DisallowedKind = 7;
  else if (T->isBitIntType())
  DisallowedKind = 8;
- else if (getLangOpts().C23 && T->isUndeducedAutoType())
- // _Atomic auto is prohibited in C23
- DisallowedKind = 9;
 
  if (DisallowedKind != -1) {
  Diag(Loc, diag::err_atomic_specifier_bad_type) << DisallowedKind << T;