When performing template argument deduction, ensure that multiple
deductions of the same template parameter are equivalent. This allows
us to implement the is_same type trait (!).
Also, move template argument deduction into its own file and update a
few build systems with this change (grrrr).
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@72819 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaTemplateDeduction.cpp b/lib/Sema/SemaTemplateDeduction.cpp
new file mode 100644
index 0000000..a55dadd
--- /dev/null
+++ b/lib/Sema/SemaTemplateDeduction.cpp
@@ -0,0 +1,121 @@
+//===------- SemaTemplateDeduction.cpp - Template Argument Deduction ------===/
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//===----------------------------------------------------------------------===/
+//
+// This file implements C++ template argument deduction.
+//
+//===----------------------------------------------------------------------===/
+
+#include "Sema.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/DeclTemplate.h"
+#include "clang/AST/StmtVisitor.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/Parse/DeclSpec.h"
+#include "llvm/Support/Compiler.h"
+using namespace clang;
+
+static bool DeduceTemplateArguments(ASTContext &Context, QualType Param,
+ QualType Arg,
+ llvm::SmallVectorImpl<TemplateArgument> &Deduced) {
+ // We only want to look at the canonical types, since typedefs and
+ // sugar are not part of template argument deduction.
+ Param = Context.getCanonicalType(Param);
+ Arg = Context.getCanonicalType(Arg);
+
+ // If the parameter type is not dependent, just compare the types
+ // directly.
+ if (!Param->isDependentType())
+ return Param == Arg;
+
+ // FIXME: Use a visitor or switch to handle all of the kinds of
+ // types that the parameter may be.
+ if (const TemplateTypeParmType *TemplateTypeParm
+ = Param->getAsTemplateTypeParmType()) {
+ // The argument type can not be less qualified than the parameter
+ // type.
+ if (Param.isMoreQualifiedThan(Arg))
+ return false;
+
+ assert(TemplateTypeParm->getDepth() == 0 && "Can't deduce with depth > 0");
+
+ unsigned Quals = Arg.getCVRQualifiers() & ~Param.getCVRQualifiers();
+ QualType DeducedType = Arg.getQualifiedType(Quals);
+ unsigned Index = TemplateTypeParm->getIndex();
+
+ if (Deduced[Index].isNull())
+ Deduced[Index] = TemplateArgument(SourceLocation(), DeducedType);
+ else {
+ // C++ [temp.deduct.type]p2:
+ // [...] If type deduction cannot be done for any P/A pair, or if for
+ // any pair the deduction leads to more than one possible set of
+ // deduced values, or if different pairs yield different deduced
+ // values, or if any template argument remains neither deduced nor
+ // explicitly specified, template argument deduction fails.
+ if (Deduced[Index].getAsType() != DeducedType)
+ return false;
+ }
+ return true;
+ }
+
+ if (Param.getCVRQualifiers() != Arg.getCVRQualifiers())
+ return false;
+
+ if (const PointerType *PointerParam = Param->getAsPointerType()) {
+ const PointerType *PointerArg = Arg->getAsPointerType();
+ if (!PointerArg)
+ return false;
+
+ return DeduceTemplateArguments(Context,
+ PointerParam->getPointeeType(),
+ PointerArg->getPointeeType(),
+ Deduced);
+ }
+
+ // FIXME: Many more cases to go (to go).
+ return false;
+}
+
+static bool
+DeduceTemplateArguments(ASTContext &Context, const TemplateArgument &Param,
+ const TemplateArgument &Arg,
+ llvm::SmallVectorImpl<TemplateArgument> &Deduced) {
+ assert(Param.getKind() == Arg.getKind() &&
+ "Template argument kind mismatch during deduction");
+ switch (Param.getKind()) {
+ case TemplateArgument::Type:
+ return DeduceTemplateArguments(Context, Param.getAsType(),
+ Arg.getAsType(), Deduced);
+
+ default:
+ return false;
+ }
+}
+
+static bool
+DeduceTemplateArguments(ASTContext &Context,
+ const TemplateArgumentList &ParamList,
+ const TemplateArgumentList &ArgList,
+ llvm::SmallVectorImpl<TemplateArgument> &Deduced) {
+ assert(ParamList.size() == ArgList.size());
+ for (unsigned I = 0, N = ParamList.size(); I != N; ++I) {
+ if (!DeduceTemplateArguments(Context, ParamList[I], ArgList[I], Deduced))
+ return false;
+ }
+ return true;
+}
+
+
+bool
+Sema::DeduceTemplateArguments(ClassTemplatePartialSpecializationDecl *Partial,
+ const TemplateArgumentList &TemplateArgs) {
+ llvm::SmallVector<TemplateArgument, 4> Deduced;
+ Deduced.resize(Partial->getTemplateParameters()->size());
+ return ::DeduceTemplateArguments(Context, Partial->getTemplateArgs(),
+ TemplateArgs, Deduced);
+}