Concepts: Create space for requires-clause in TemplateParameterList; NFC

Summary:
Space for storing the //constraint-expression// of the
//requires-clause// associated with a `TemplateParameterList` is
arranged by taking a bit out of the `NumParams` field for the purpose
of determining whether there is a //requires-clause// or not, and by
adding to the trailing objects tied to the `TemplateParameterList`. An
accessor is provided.

An appropriate argument is supplied to `TemplateParameterList::Create`
at the various call sites.

Serialization changes will addressed as the Concepts implementation
becomes more solid.

Drive-by fix:
This change also replaces the custom
`FixedSizeTemplateParameterListStorage` implementation with one that
follows the interface provided by `llvm::TrailingObjects`.

Reviewers: aaron.ballman, faisalv, rsmith

Subscribers: cfe-commits, nwilson

Differential Revision: https://reviews.llvm.org/D19322

llvm-svn: 276069

1 files changed, 18 insertions, 10 deletions

diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
index 37943cdd5b7..bcc8878eeae 100644
--- a/clang/lib/AST/DeclTemplate.cpp
+++ b/clang/lib/AST/DeclTemplate.cpp
@@ -31,9 +31,11 @@ using namespace clang;
 TemplateParameterList::TemplateParameterList(SourceLocation TemplateLoc,
                                              SourceLocation LAngleLoc,
                                              ArrayRef<NamedDecl *> Params,
-                                             SourceLocation RAngleLoc)
+                                             SourceLocation RAngleLoc,
+                                             Expr *RequiresClause)
   : TemplateLoc(TemplateLoc), LAngleLoc(LAngleLoc), RAngleLoc(RAngleLoc),
-    NumParams(Params.size()), ContainsUnexpandedParameterPack(false) {
+    NumParams(Params.size()), ContainsUnexpandedParameterPack(false),
+    HasRequiresClause(static_cast<bool>(RequiresClause)) {
   assert(this->NumParams == NumParams && "Too many template parameters");
   for (unsigned Idx = 0; Idx < NumParams; ++Idx) {
     NamedDecl *P = Params[Idx];
@@ -52,15 +54,21 @@ TemplateParameterList::TemplateParameterList(SourceLocation TemplateLoc,
       // template parameter list does too.
     }
   }
+  if (RequiresClause) {
+    *getTrailingObjects<Expr *>() = RequiresClause;
+  }
 }
 
-TemplateParameterList *TemplateParameterList::Create(
-    const ASTContext &C, SourceLocation TemplateLoc, SourceLocation LAngleLoc,
-    ArrayRef<NamedDecl *> Params, SourceLocation RAngleLoc) {
-  void *Mem = C.Allocate(totalSizeToAlloc<NamedDecl *>(Params.size()),
+TemplateParameterList *
+TemplateParameterList::Create(const ASTContext &C, SourceLocation TemplateLoc,
+                              SourceLocation LAngleLoc,
+                              ArrayRef<NamedDecl *> Params,
+                              SourceLocation RAngleLoc, Expr *RequiresClause) {
+  void *Mem = C.Allocate(totalSizeToAlloc<NamedDecl *, Expr *>(
+                             Params.size(), RequiresClause ? 1u : 0u),
                          llvm::alignOf<TemplateParameterList>());
   return new (Mem) TemplateParameterList(TemplateLoc, LAngleLoc, Params,
-                                         RAngleLoc);
+                                         RAngleLoc, RequiresClause);
 }
 
 unsigned TemplateParameterList::getMinRequiredArguments() const {
@@ -1169,7 +1177,7 @@ createMakeIntegerSeqParameterList(const ASTContext &C, DeclContext *DC) {
   // <typename T, T ...Ints>
   NamedDecl *P[2] = {T, N};
   auto *TPL = TemplateParameterList::Create(
-      C, SourceLocation(), SourceLocation(), P, SourceLocation());
+      C, SourceLocation(), SourceLocation(), P, SourceLocation(), nullptr);
 
   // template <typename T, ...Ints> class IntSeq
   auto *TemplateTemplateParm = TemplateTemplateParmDecl::Create(
@@ -1194,7 +1202,7 @@ createMakeIntegerSeqParameterList(const ASTContext &C, DeclContext *DC) {
 
   // template <template <typename T, T ...Ints> class IntSeq, typename T, T N>
   return TemplateParameterList::Create(C, SourceLocation(), SourceLocation(),
-                                       Params, SourceLocation());
+                                       Params, SourceLocation(), nullptr);
 }
 
 static TemplateParameterList *
@@ -1215,7 +1223,7 @@ createTypePackElementParameterList(const ASTContext &C, DeclContext *DC) {
   NamedDecl *Params[] = {Index, Ts};
   return TemplateParameterList::Create(C, SourceLocation(), SourceLocation(),
                                        llvm::makeArrayRef(Params),
-                                       SourceLocation());
+                                       SourceLocation(), nullptr);
 }
 
 static TemplateParameterList *createBuiltinTemplateParameterList(