P1286R2: Remove restriction that the exception specification of a

defaulted special member matches the implicit exception specification.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@360011 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 19 insertions, 66 deletions

diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index b8740960fc..8ddc5f12cf 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -6636,6 +6636,8 @@ void Sema::CheckExplicitlyDefaultedSpecialMember(CXXMethodDecl *MD) {
   // makes such functions always instantiate to constexpr functions. For
   // functions which cannot be constexpr (for non-constructors in C++11 and for
   // destructors in C++1y), this is checked elsewhere.
+  //
+  // FIXME: This should not apply if the member is deleted.
   bool Constexpr = defaultedSpecialMemberIsConstexpr(*this, RD, CSM,
                                                      HasConstParam);
   if ((getLangOpts().CPlusPlus14 ? !isa<CXXDestructorDecl>(MD)
@@ -6647,38 +6649,26 @@ void Sema::CheckExplicitlyDefaultedSpecialMember(CXXMethodDecl *MD) {
     HadError = true;
   }
 
-  //   and may have an explicit exception-specification only if it is compatible
-  //   with the exception-specification on the implicit declaration.
-  if (Type->hasExceptionSpec()) {
-    // Delay the check if this is the first declaration of the special member,
-    // since we may not have parsed some necessary in-class initializers yet.
-    if (First) {
-      // If the exception specification needs to be instantiated, do so now,
-      // before we clobber it with an EST_Unevaluated specification below.
-      if (Type->getExceptionSpecType() == EST_Uninstantiated) {
-        InstantiateExceptionSpec(MD->getBeginLoc(), MD);
-        Type = MD->getType()->getAs<FunctionProtoType>();
-      }
-      DelayedDefaultedMemberExceptionSpecs.push_back(std::make_pair(MD, Type));
-    } else
-      CheckExplicitlyDefaultedMemberExceptionSpec(MD, Type);
-  }
-
-  //   If a function is explicitly defaulted on its first declaration,
   if (First) {
-    //  -- it is implicitly considered to be constexpr if the implicit
-    //     definition would be,
+    // C++2a [dcl.fct.def.default]p3:
+    //   If a function is explicitly defaulted on its first declaration, it is
+    //   implicitly considered to be constexpr if the implicit declaration
+    //   would be.
     MD->setConstexpr(Constexpr);
 
-    //  -- it is implicitly considered to have the same exception-specification
-    //     as if it had been implicitly declared,
-    FunctionProtoType::ExtProtoInfo EPI = Type->getExtProtoInfo();
-    EPI.ExceptionSpec.Type = EST_Unevaluated;
-    EPI.ExceptionSpec.SourceDecl = MD;
-    MD->setType(Context.getFunctionType(ReturnType,
-                                        llvm::makeArrayRef(&ArgType,
-                                                           ExpectedParams),
-                                        EPI));
+    if (!Type->hasExceptionSpec()) {
+      // C++2a [except.spec]p3:
+      //   If a declaration of a function does not have a noexcept-specifier
+      //   [and] is defaulted on its first declaration, [...] the exception
+      //   specification is as specified below
+      FunctionProtoType::ExtProtoInfo EPI = Type->getExtProtoInfo();
+      EPI.ExceptionSpec.Type = EST_Unevaluated;
+      EPI.ExceptionSpec.SourceDecl = MD;
+      MD->setType(Context.getFunctionType(ReturnType,
+                                          llvm::makeArrayRef(&ArgType,
+                                                             ExpectedParams),
+                                          EPI));
+    }
   }
 
   if (ShouldDeleteForTypeMismatch || ShouldDeleteSpecialMember(MD, CSM)) {
@@ -6711,43 +6701,12 @@ void Sema::CheckExplicitlyDefaultedSpecialMember(CXXMethodDecl *MD) {
     MD->setInvalidDecl();
 }
 
-/// Check whether the exception specification provided for an
-/// explicitly-defaulted special member matches the exception specification
-/// that would have been generated for an implicit special member, per
-/// C++11 [dcl.fct.def.default]p2.
-void Sema::CheckExplicitlyDefaultedMemberExceptionSpec(
-    CXXMethodDecl *MD, const FunctionProtoType *SpecifiedType) {
-  // If the exception specification was explicitly specified but hadn't been
-  // parsed when the method was defaulted, grab it now.
-  if (SpecifiedType->getExceptionSpecType() == EST_Unparsed)
-    SpecifiedType =
-        MD->getTypeSourceInfo()->getType()->castAs<FunctionProtoType>();
-
-  // Compute the implicit exception specification.
-  CallingConv CC = Context.getDefaultCallingConvention(/*IsVariadic=*/false,
-                                                       /*IsCXXMethod=*/true);
-  FunctionProtoType::ExtProtoInfo EPI(CC);
-  auto IES = computeImplicitExceptionSpec(*this, MD->getLocation(), MD);
-  EPI.ExceptionSpec = IES.getExceptionSpec();
-  const FunctionProtoType *ImplicitType = cast<FunctionProtoType>(
-    Context.getFunctionType(Context.VoidTy, None, EPI));
-
-  // Ensure that it matches.
-  CheckEquivalentExceptionSpec(
-    PDiag(diag::err_incorrect_defaulted_exception_spec)
-      << getSpecialMember(MD), PDiag(),
-    ImplicitType, SourceLocation(),
-    SpecifiedType, MD->getLocation());
-}
-
 void Sema::CheckDelayedMemberExceptionSpecs() {
   decltype(DelayedOverridingExceptionSpecChecks) Overriding;
   decltype(DelayedEquivalentExceptionSpecChecks) Equivalent;
-  decltype(DelayedDefaultedMemberExceptionSpecs) Defaulted;
 
   std::swap(Overriding, DelayedOverridingExceptionSpecChecks);
   std::swap(Equivalent, DelayedEquivalentExceptionSpecChecks);
-  std::swap(Defaulted, DelayedDefaultedMemberExceptionSpecs);
 
   // Perform any deferred checking of exception specifications for virtual
   // destructors.
@@ -6758,11 +6717,6 @@ void Sema::CheckDelayedMemberExceptionSpecs() {
   // special members.
   for (auto &Check : Equivalent)
     CheckEquivalentExceptionSpec(Check.second, Check.first);
-
-  // Check that any explicitly-defaulted methods have exception specifications
-  // compatible with their implicit exception specifications.
-  for (auto &Spec : Defaulted)
-    CheckExplicitlyDefaultedMemberExceptionSpec(Spec.first, Spec.second);
 }
 
 namespace {
@@ -11398,7 +11352,6 @@ void Sema::ActOnFinishCXXMemberDecls() {
     if (Record->isInvalidDecl()) {
       DelayedOverridingExceptionSpecChecks.clear();
       DelayedEquivalentExceptionSpecChecks.clear();
-      DelayedDefaultedMemberExceptionSpecs.clear();
       return;
     }
     checkForMultipleExportedDefaultConstructors(*this, Record);