c++: Explain fn template argument type/value mismatches [PR66439]

In fn_type_unifcation, we are passing NULL_TREE as the 'in_decl'
parameter to coerce_template_parms, and this is causing template
type/value mismatch error messages to get suppressed regardless of the
value of 'complain'.

This means that when substitution into a function template fails due to
a type/value mismatch between a template parameter and the provided
template argument, we just say "template argument deduction/substitution
failed:" without a followup explanation of the failure.

Fix this by passing 'fn' instead of NULL_TREE to coerce_template_parms.

gcc/cp/ChangeLog:

	PR c++/66439
	* pt.c (fn_type_unification): Pass 'fn' instead of NULL_TREE as
	the 'in_decl' parameter to coerce_template_parms.

gcc/testsuite/ChangeLog:

	PR c++/66439
	* g++.dg/cpp2a/concepts-ts4.C: Expect a "type/value mismatch"
	diagnostic.
	* g++.dg/cpp2a/concepts-ts6.C: Likewise.
	* g++.dg/template/error56.C: Likewise.
	* g++.dg/template/error59.C: New test.

libstdc++-v3/ChangeLog:

	PR c++/66439
	* testsuite/20_util/pair/astuple/get_neg.cc: Prune "type/value
	mismatch" messages.
	* testsuite/20_util/tuple/element_access/get_neg.cc: Likewise.

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 4e446585aa42f4104057155e4c06a4f9573ea746..cd81891201da8489ce731b354de8550b6260adc5 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2020-05-19  Patrick Palka  <ppalka@redhat.com>
+
+       PR c++/66439
+       * pt.c (fn_type_unification): Pass 'fn' instead of NULL_TREE as
+       the 'in_decl' parameter to coerce_template_parms.
+
 2020-05-18  Marek Polacek  <polacek@redhat.com>
 
        PR c++/94955

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index cad5b217f3c365a1594f9b472fec743b89bd8492..50933cbc23bef46a20b0852b2510c02920e00629 100644 (file)
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -20989,7 +20989,7 @@ fn_type_unification (tree fn,
       /* Adjust any explicit template arguments before entering the
         substitution context.  */
       explicit_targs
-       = (coerce_template_parms (tparms, explicit_targs, NULL_TREE,
+       = (coerce_template_parms (tparms, explicit_targs, fn,
                                  complain|tf_partial,
                                  /*require_all_args=*/false,
                                  /*use_default_args=*/false));

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 02de8028552991f2c2572deff25f99e661c54ce6..b0315b0207bd86f9e47783c8bca3db6469fd7f62 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,12 @@
+2020-05-19  Patrick Palka  <ppalka@redhat.com>
+
+       PR c++/66439
+       * g++.dg/cpp2a/concepts-ts4.C: Expect a "type/value mismatch"
+       diagnostic.
+       * g++.dg/cpp2a/concepts-ts6.C: Likewise.
+       * g++.dg/template/error56.C: Likewise.
+       * g++.dg/template/error59.C: New test.
+
 2020-05-18  Marek Polacek  <polacek@redhat.com>
 
        PR c++/94955

diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-ts4.C b/gcc/testsuite/g++.dg/cpp2a/concepts-ts4.C
index 23ed929acf4fc79d4ec4db046c56f095f0fd0992..cc49ff4fb278637c50a89e94f3f7f5e92b6f10c1 100644 (file)
--- a/gcc/testsuite/g++.dg/cpp2a/concepts-ts4.C
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-ts4.C
@@ -31,4 +31,6 @@ void driver()
   fn<0>(); // OK
   fn<-1>(); // { dg-error "" }
   fn<int>(); // { dg-error "no matching function" }
+  // { dg-error "type/value mismatch at argument 1" "" { target *-*-* } .-1 }
+  // { dg-message "expected a constant of type .int., got .int." "" { target *-*-* } .-2 }
 }

diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-ts6.C b/gcc/testsuite/g++.dg/cpp2a/concepts-ts6.C
index 597ad5e1ae1e712af441d520248404b140c9f8fb..8aede575f7553e377bff6322d90ee812dda756ac 100644 (file)
--- a/gcc/testsuite/g++.dg/cpp2a/concepts-ts6.C
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-ts6.C
@@ -25,6 +25,8 @@ void driver1() {
 
   f<X>();
   f<int>(); // { dg-error "no matching function for call" }
+  // { dg-error "type/value mismatch at argument 1" "" { target *-*-* } .-1 }
+  // { dg-message "expected a class template, got .int." "" { target *-*-* } .-2 }
 
   S2<int> s2a;
   S2<char, signed char, unsigned char> s2b;
@@ -69,4 +71,4 @@ void driver2()
   S6<void, void> s6a;
   S6<void, int> s6c; // { dg-error "template constraint failure" }
   S6<void, void, void> s6b; // { dg-error "wrong number of template arguments" }
-}
\ No newline at end of file
+}

diff --git a/gcc/testsuite/g++.dg/template/error56.C b/gcc/testsuite/g++.dg/template/error56.C
index 3eda04c322523478f69fd89ac35935d721e90eca..e85471a50b09fcb0f3c4d616e034961de3b785f4 100644 (file)
--- a/gcc/testsuite/g++.dg/template/error56.C
+++ b/gcc/testsuite/g++.dg/template/error56.C
@@ -9,4 +9,6 @@ struct A
 int main()
 {
   A().f<1>();                  // { dg-error "f<1>" }
+  // { dg-error "type/value mismatch at argument 1" "" { target *-*-* } .-1 }
+  // { dg-message "expected a type, got .1." "" { target *-*-* } .-2 }
 }

diff --git a/gcc/testsuite/g++.dg/template/error59.C b/gcc/testsuite/g++.dg/template/error59.C
new file mode 100644 (file)
index 0000000..f81a28c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/error59.C
@@ -0,0 +1,11 @@
+template<int N> struct S { };
+
+template<template<typename> class TT>
+void foo();
+
+void bar()
+{
+  foo<S>(); // { dg-error "no matching function" }
+  // { dg-error "type/value mismatch at argument 1" "" { target *-*-* } .-1 }
+  // { dg-message "expected a template of type .template<class> class TT., got .template<int N> struct S." "" { target *-*-* } .-2 }
+}

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index dde62ad477970b474503d0e1a7d894ed3dcf2f8d..ae1ec87589c23cf6a7a6e315df90c56ed5c7e16c 100644 (file)
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,10 @@
+2020-05-19  Patrick Palka  <ppalka@redhat.com>
+
+       PR c++/66439
+       * testsuite/20_util/pair/astuple/get_neg.cc: Prune "type/value
+       mismatch" messages.
+       * testsuite/20_util/tuple/element_access/get_neg.cc: Likewise.
+
 2020-05-15  H.J. Lu  <hongjiu.lu@intel.com>
 
        PR bootstrap/95147

diff --git a/libstdc++-v3/testsuite/20_util/pair/astuple/get_neg.cc b/libstdc++-v3/testsuite/20_util/pair/astuple/get_neg.cc
index bcf3940e16d91b08b5b1aa6a220e69c2bb5f9709..1f76aef6d73f292c9d728b45e9ad03b8dab339fa 100644 (file)
--- a/libstdc++-v3/testsuite/20_util/pair/astuple/get_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/pair/astuple/get_neg.cc
@@ -27,3 +27,4 @@ void test01()
 }
 
 // { dg-prune-output "tuple_element<2" }
+// { dg-prune-output "type/value mismatch" }

diff --git a/libstdc++-v3/testsuite/20_util/tuple/element_access/get_neg.cc b/libstdc++-v3/testsuite/20_util/tuple/element_access/get_neg.cc
index 8488e287a9883830621e23ee22e4d6e7fae3dbe4..03ad77215d276837d7f4be979a3c59df2d4bfb35 100644 (file)
--- a/libstdc++-v3/testsuite/20_util/tuple/element_access/get_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/tuple/element_access/get_neg.cc
@@ -61,3 +61,4 @@ test03()
 }
 
 // { dg-prune-output "no type named .type" }
+// { dg-prune-output "type/value mismatch" }