From: Douglas Gregor <dgregor@apple.com>
Date: Wed, 5 Jan 2011 23:23:17 +0000 (+0000)
Subject: Fast-path an arity check when performing template argument deduction that compares... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=0bbacf8d2b3c7a5f19f292f3201e371836445502;p=clang

Fast-path an arity check when performing template argument deduction that compares two parameter-type-lists. No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@122928 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Sema/SemaTemplateDeduction.cpp b/lib/Sema/SemaTemplateDeduction.cpp
index e762d34117..603a7efea5 100644
--- a/lib/Sema/SemaTemplateDeduction.cpp
+++ b/lib/Sema/SemaTemplateDeduction.cpp
@@ -541,8 +541,12 @@ DeduceTemplateArguments(Sema &S,
                         TemplateDeductionInfo &Info,
                       llvm::SmallVectorImpl<DeducedTemplateArgument> &Deduced,
                         unsigned TDF) {
-  // FIXME: Fast-path check with NumParams != NumArgs and there are no
-  // pack expansions around.
+  // Fast-path check to see if we have too many/too few arguments.
+  if (NumParams != NumArgs &&
+      !(NumParams && isa<PackExpansionType>(Params[NumParams - 1])) &&
+      !(NumArgs && isa<PackExpansionType>(Args[NumArgs - 1])))
+    return NumArgs < NumParams ? Sema::TDK_TooFewArguments 
+                               : Sema::TDK_TooManyArguments;
   
   // C++0x [temp.deduct.type]p10:
   //   Similarly, if P has a form that contains (T), then each parameter type