Instantiate exception specifications when instantiating function types (other

than the type of a function declaration). We previously didn't instantiate
these at all! This also covers the pathological case where the only mention of
a parameter pack is within the exception specification; this gives us a second
way (other than alias templates) to reach the horrible state where a type
contains an unexpanded pack, but its canonical type does not.


This is a re-commit of r219977:

r219977 was reverted in r220038 because it hit a wrong-code bug in GCC 4.7.2.
(That's gcc.gnu.org/PR56135, and affects any implicit lambda-capture of
'this' within a template.)


r219977 was a re-commit of r217995, r218011, and r218053:

r217995 was reverted in r218058 because it hit a rejects-valid bug in MSVC.
(Incorrect overload resolution in the presence of using-declarations.)
It was re-committed in r219977 with a workaround for the MSVC rejects-valid.

r218011 was a workaround for an MSVC parser bug. (Incorrect desugaring of
unbraced range-based for loop).

llvm-svn: 221750

1 files changed, 20 insertions, 7 deletions

diff --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
index e9d474a174c..19a3add700d 100644
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -1625,9 +1625,9 @@ FunctionProtoType::FunctionProtoType(QualType result, ArrayRef<QualType> params,
     QualType *exnSlot = argSlot + NumParams;
     unsigned I = 0;
     for (QualType ExceptionType : epi.ExceptionSpec.Exceptions) {
-      if (ExceptionType->isDependentType())
-        setDependent();
-      else if (ExceptionType->isInstantiationDependentType())
+      // Note that a dependent exception specification does *not* make
+      // a type dependent; it's not even part of the C++ type system.
+      if (ExceptionType->isInstantiationDependentType())
         setInstantiationDependent();
 
       if (ExceptionType->containsUnexpandedParameterPack())
@@ -1641,11 +1641,12 @@ FunctionProtoType::FunctionProtoType(QualType result, ArrayRef<QualType> params,
     *noexSlot = epi.ExceptionSpec.NoexceptExpr;
 
     if (epi.ExceptionSpec.NoexceptExpr) {
-      if (epi.ExceptionSpec.NoexceptExpr->isValueDependent() 
-          || epi.ExceptionSpec.NoexceptExpr->isTypeDependent())
-        setDependent();
-      else if (epi.ExceptionSpec.NoexceptExpr->isInstantiationDependent())
+      if (epi.ExceptionSpec.NoexceptExpr->isValueDependent() ||
+          epi.ExceptionSpec.NoexceptExpr->isInstantiationDependent())
         setInstantiationDependent();
+
+      if (epi.ExceptionSpec.NoexceptExpr->containsUnexpandedParameterPack())
+        setContainsUnexpandedParameterPack();
     }
   } else if (getExceptionSpecType() == EST_Uninstantiated) {
     // Store the function decl from which we will resolve our
@@ -1671,6 +1672,18 @@ FunctionProtoType::FunctionProtoType(QualType result, ArrayRef<QualType> params,
   }
 }
 
+bool FunctionProtoType::hasDependentExceptionSpec() const {
+  if (Expr *NE = getNoexceptExpr())
+    return NE->isValueDependent();
+  for (QualType ET : exceptions())
+    // A pack expansion with a non-dependent pattern is still dependent,
+    // because we don't know whether the pattern is in the exception spec
+    // or not (that depends on whether the pack has 0 expansions).
+    if (ET->isDependentType() || ET->getAs<PackExpansionType>())
+      return true;
+  return false;
+}
+
 FunctionProtoType::NoexceptResult
 FunctionProtoType::getNoexceptSpec(const ASTContext &ctx) const {
   ExceptionSpecificationType est = getExceptionSpecType();