WIP implementation of explicit function template specialization. This

first implementation recognizes when a function declaration is an
explicit function template specialization (based on the presence of a
template<> header), performs template argument deduction + ambiguity
resolution to determine which template is being specialized, and hooks

There are many caveats here:
  - We completely and totally drop any explicitly-specified template
  arguments on the floor
  - We don't diagnose any of the extra semantic things that we should
  diagnose. 
  - I haven't looked to see that we're getting the right linkage for
  explicit specializations

On a happy note, this silences a bunch of errors that show up in
libstdc++'s <iostream>, although Clang still can't get through the
entire header.

llvm-svn: 82728

1 files changed, 25 insertions, 0 deletions

diff --git a/clang/test/SemaTemplate/function-template-specialization.cpp b/clang/test/SemaTemplate/function-template-specialization.cpp
new file mode 100644
index 00000000000..5946d9b680b
--- /dev/null
+++ b/clang/test/SemaTemplate/function-template-specialization.cpp
@@ -0,0 +1,25 @@
+// RUN: clang-cc -fsyntax-only -verify %s
+
+template<int N> void f0(int (&array)[N]);
+
+// Simple function template specialization (using overloading)
+template<> void f0(int (&array)[1]);
+
+void test_f0() {
+  int iarr1[1];
+  f0(iarr1);
+}
+
+// Function template specialization where there are no matches
+template<> void f0(char (&array)[1]); // expected-error{{no function template matches}}
+
+// Function template specialization that requires partial ordering
+template<typename T, int N> void f1(T (&array)[N]); // expected-note{{matches}}
+template<int N> void f1(int (&array)[N]); // expected-note{{matches}}
+
+template<> void f1(float (&array)[1]);
+template<> void f1(int (&array)[1]);
+
+// Function template specialization that results in an ambiguity
+template<typename T> void f1(T (&array)[17]); // expected-note{{matches}}
+template<> void f1(int (&array)[17]); // expected-error{{ambiguous}}