Improve 'failed template argument deduction' diagnostic for the case where we

have a direct mismatch between some component of the template and some
component of the argument. The diagnostic now says what the mismatch was, but
doesn't yet say which part of the template doesn't match.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174039 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 8 insertions, 7 deletions

diff --git a/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/basic.cpp b/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/basic.cpp
index 90d29497f4..4f6dcc1105 100644
--- a/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/basic.cpp
+++ b/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/basic.cpp
@@ -15,8 +15,7 @@ void test_f1(int *ip, float fv) {
   f1(ip, fv);
 }
 
-// TODO: this diagnostic can and should improve
-template<typename T> void f2(T*, T*); // expected-note {{candidate template ignored: failed template argument deduction}} \
+template<typename T> void f2(T*, T*); // expected-note {{candidate template ignored: could not match 'T *' against 'ConvToIntPtr'}} \
 // expected-note{{candidate template ignored: deduced conflicting types for parameter 'T' ('int' vs. 'float')}}
 
 struct ConvToIntPtr {
diff --git a/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p1-0x.cpp b/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p1-0x.cpp
index 8b192fa547..cd1d9f15c7 100644
--- a/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p1-0x.cpp
+++ b/test/CXX/temp/temp.fct.spec/temp.deduct/temp.deduct.call/p1-0x.cpp
@@ -53,8 +53,9 @@ void test_simple_ref_deduction(int *ip, float *fp, double *dp) {
 }
 
 
+// FIXME: Use the template parameter names in this diagnostic.
 template<typename ...Args1, typename ...Args2>
-typename get_nth_type<0, Args1...>::type first_arg_pair(pair<Args1, Args2>...); // expected-note{{candidate template ignored: failed template argument deduction}}
+typename get_nth_type<0, Args1...>::type first_arg_pair(pair<Args1, Args2>...); // expected-note{{candidate template ignored: could not match 'pair<type-parameter-0-0, type-parameter-0-1>' against 'int'}}
 
 template<typename ...Args1, typename ...Args2>
 typename get_nth_type<1, Args1...>::type second_arg_pair(pair<Args1, Args2>...);
diff --git a/test/SemaCXX/c99-variable-length-array.cpp b/test/SemaCXX/c99-variable-length-array.cpp
index de9c11e565..bb620c71fa 100644
--- a/test/SemaCXX/c99-variable-length-array.cpp
+++ b/test/SemaCXX/c99-variable-length-array.cpp
@@ -64,8 +64,9 @@ X1<HasConstantValue> x1a;
 X1<HasNonConstantValue> x1b; // expected-note{{in instantiation of}}
 
 // Template argument deduction does not allow deducing a size from a VLA.
+// FIXME: This diagnostic should make it clear that the two 'N's are different entities!
 template<typename T, unsigned N>
-void accept_array(T (&array)[N]); // expected-note{{candidate template ignored: failed template argument deduction}}
+void accept_array(T (&array)[N]); // expected-note{{candidate template ignored: could not match 'T [N]' against 'int [N]'}}
 
 void test_accept_array(int N) {
   int array[N]; // expected-warning{{variable length arrays are a C99 feature}}
diff --git a/test/SemaTemplate/instantiate-init.cpp b/test/SemaTemplate/instantiate-init.cpp
index adcc06fa37..6a1a57ca65 100644
--- a/test/SemaTemplate/instantiate-init.cpp
+++ b/test/SemaTemplate/instantiate-init.cpp
@@ -78,7 +78,7 @@ namespace PR7985 {
   template<int N> struct integral_c { };
 
   template <typename T, int N>
-  integral_c<N> array_lengthof(T (&x)[N]) { return integral_c<N>(); } // expected-note 2{{candidate template ignored: failed template argument deduction}}
+  integral_c<N> array_lengthof(T (&x)[N]) { return integral_c<N>(); } // expected-note 2{{candidate template ignored: could not match 'T [N]' against 'const Data<}}
 
   template<typename T>
   struct Data {
diff --git a/test/SemaTemplate/operator-template.cpp b/test/SemaTemplate/operator-template.cpp
index 777b0f5f42..30d6ccfb95 100644
--- a/test/SemaTemplate/operator-template.cpp
+++ b/test/SemaTemplate/operator-template.cpp
@@ -2,7 +2,7 @@
 
 // Make sure we accept this
 template<class X>struct A{typedef X Y;};
-template<class X>bool operator==(A<X>,typename A<X>::Y); // expected-note{{candidate template ignored: failed template argument deduction}}
+template<class X>bool operator==(A<X>,typename A<X>::Y); // expected-note{{candidate template ignored: could not match 'A<type-parameter-0-0>' against 'B<int> *'}}
 
 int a(A<int> x) { return operator==(x,1); }
 
diff --git a/test/SemaTemplate/recursive-template-instantiation.cpp b/test/SemaTemplate/recursive-template-instantiation.cpp
index d6a0b247dd..fe37060185 100644
--- a/test/SemaTemplate/recursive-template-instantiation.cpp
+++ b/test/SemaTemplate/recursive-template-instantiation.cpp
@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s
 
-template<typename T> void f(T* t) { // expected-note{{failed template argument deduction}}
+template<typename T> void f(T* t) { // expected-note{{could not match 'T *' against 'int'}}
   f(*t); // expected-error{{no matching function}}\
          // expected-note 3{{requested here}}
 }