PR libstdc++/83025 fix constraints for path overloads in <fstream>

	PR libstdc++/83025
	* include/std/fstream (basic_filebuf::_If_path): Move to
	namespace-scope and rename to _If_fs_path.
	(basic_filebuf::open): Use new name.
	(basic_ifstream(_Path, ios::openmode))
	(basic_ifstream::open(_Path, ios::openmode))
	(basic_ofstream(_Path, ios::openmode))
	(basic_ofstream::open(_Path, ios::openmode))
	(basic_fstream(_Path, ios::openmode))
	(basic_fstream::open(_Path, ios::openmode)): Use _If_fs_path.
	* testsuite/27_io/basic_filebuf/open/char/path.cc: Test with filename
	as non-const char*.
	* testsuite/27_io/basic_fstream/cons/char/path.cc: Likewise.
	* testsuite/27_io/basic_fstream/open/char/path.cc: Likewise.
	* testsuite/27_io/basic_ifstream/cons/char/path.cc: Likewise.
	* testsuite/27_io/basic_ifstream/open/char/path.cc: Likewise.
	* testsuite/27_io/basic_ofstream/cons/char/path.cc: Likewise.
	* testsuite/27_io/basic_ofstream/open/char/path.cc: Likewise.

From-SVN: r254871

9 files changed, 91 insertions, 26 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 3c9f3e7..3755ce6 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,25 @@
+2017-11-17  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/83025
+	* include/std/fstream (basic_filebuf::_If_path): Move to
+	namespace-scope and rename to _If_fs_path.
+	(basic_filebuf::open): Use new name.
+	(basic_ifstream(_Path, ios::openmode))
+	(basic_ifstream::open(_Path, ios::openmode))
+	(basic_ofstream(_Path, ios::openmode))
+	(basic_ofstream::open(_Path, ios::openmode))
+	(basic_fstream(_Path, ios::openmode))
+	(basic_fstream::open(_Path, ios::openmode)): Use _If_fs_path.
+	* testsuite/27_io/basic_filebuf/open/char/path.cc: Test with filename
+	as non-const char*.
+	* testsuite/27_io/basic_fstream/cons/char/path.cc: Likewise.
+	* testsuite/27_io/basic_fstream/open/char/path.cc: Likewise.
+	* testsuite/27_io/basic_ifstream/cons/char/path.cc: Likewise.
+	* testsuite/27_io/basic_ifstream/open/char/path.cc: Likewise.
+	* testsuite/27_io/basic_ofstream/cons/char/path.cc: Likewise.
+	* testsuite/27_io/basic_ofstream/open/char/path.cc: Likewise.
+
+
 2017-11-17  Marc Glisse  <marc.glisse@inria.fr>
 
 	* include/bits/vector.tcc (vector::_M_realloc_insert): Cache old
diff --git a/libstdc++-v3/include/std/fstream b/libstdc++-v3/include/std/fstream
index 26176af..503bdd6 100644
--- a/libstdc++-v3/include/std/fstream
+++ b/libstdc++-v3/include/std/fstream
@@ -48,6 +48,14 @@ namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
+#if __cplusplus >= 201703L
+  // Enable if _Path is a filesystem::path or experimental::filesystem::path
+  template<typename _Path, typename _Result = _Path, typename _Path2
+	   = decltype(std::declval<_Path&>().make_preferred().filename())>
+    using _If_fs_path = enable_if_t<is_same_v<_Path, _Path2>, _Result>;
+#endif // C++17
+
+
   // [27.8.1.1] template class basic_filebuf
   /**
    *  @brief  The actual work of input and output (for files).
@@ -216,12 +224,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  }
       }
 
-#if __cplusplus >= 201703L
-      template<typename _Path, typename _Result = _Path, typename _Path2
-	       = decltype(std::declval<_Path&>().make_preferred().native())>
-	using _If_path = enable_if_t<is_same_v<_Path, _Path2>, _Result>;
-#endif // C++17
-
     public:
       // Constructors/destructor:
       /**
@@ -321,7 +323,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *  @return  @c this on success, NULL on failure
        */
       template<typename _Path>
-	_If_path<_Path, __filebuf_type*>
+	_If_fs_path<_Path, __filebuf_type*>
 	open(const _Path& __s, ios_base::openmode __mode)
 	{ return open(__s.c_str(), __mode); }
 #endif // C++17
@@ -540,8 +542,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *
        *  @c ios_base::in is automatically included in @a __mode.
        */
-      template<typename _Path, typename = _Require<
-	  is_constructible<__filebuf_type, const _Path&, ios_base::openmode>>>
+      template<typename _Path, typename _Require = _If_fs_path<_Path>>
 	basic_ifstream(const _Path& __s,
 		       ios_base::openmode __mode = ios_base::in)
 	: basic_ifstream(__s.c_str(), __mode)
@@ -661,9 +662,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *  fails, @c failbit is set in the stream's error state.
        */
       template<typename _Path>
-	auto
+	_If_fs_path<_Path, void>
 	open(const _Path& __s, ios_base::openmode __mode = ios_base::in)
-	-> decltype((void)_M_filebuf.open(__s, __mode))
 	{ open(__s.c_str(), __mode); }
 #endif // C++17
 #endif // C++11
@@ -768,8 +768,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *
        *  @c ios_base::out is automatically included in @a __mode.
        */
-      template<typename _Path, typename = _Require<
-	  is_constructible<__filebuf_type, const _Path&, ios_base::openmode>>>
+      template<typename _Path, typename _Require = _If_fs_path<_Path>>
 	basic_ofstream(const _Path& __s,
 		       ios_base::openmode __mode = ios_base::out)
 	: basic_ofstream(__s.c_str(), __mode)
@@ -889,9 +888,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *  function fails, @c failbit is set in the stream's error state.
        */
       template<typename _Path>
-	auto
+	_If_fs_path<_Path, void>
 	open(const _Path& __s, ios_base::openmode __mode = ios_base::out)
-	-> decltype((void)_M_filebuf.open(__s, __mode))
 	{ open(__s.c_str(), __mode); }
 #endif // C++17
 #endif // C++11
@@ -992,8 +990,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *  @param  __s  filesystem::path specifying the filename.
        *  @param  __mode  Open file in specified mode (see std::ios_base).
        */
-      template<typename _Path, typename = _Require<
-	  is_constructible<__filebuf_type, const _Path&, ios_base::openmode>>>
+      template<typename _Path, typename _Require = _If_fs_path<_Path>>
 	basic_fstream(const _Path& __s,
 		      ios_base::openmode __mode = ios_base::in | ios_base::out)
 	: basic_fstream(__s.c_str(), __mode)
@@ -1115,10 +1112,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
        *  function fails, @c failbit is set in the stream's error state.
        */
       template<typename _Path>
-	auto
+	_If_fs_path<_Path, void>
 	open(const _Path& __s,
 	     ios_base::openmode __mode = ios_base::in | ios_base::out)
-	-> decltype((void)_M_filebuf.open(__s, __mode))
 	{ open(__s.c_str(), __mode); }
 #endif // C++17
 #endif // C++11
diff --git a/libstdc++-v3/testsuite/27_io/basic_filebuf/open/char/path.cc b/libstdc++-v3/testsuite/27_io/basic_filebuf/open/char/path.cc
index 56fffde..51f0839 100644
--- a/libstdc++-v3/testsuite/27_io/basic_filebuf/open/char/path.cc
+++ b/libstdc++-v3/testsuite/27_io/basic_filebuf/open/char/path.cc
@@ -24,7 +24,8 @@
 #include <filesystem>
 #include <testsuite_hooks.h>
 
-const std::filesystem::path filename = "filebuf_members-1.tst";
+char cstr[] = "filebuf_members-1.tst";
+const std::filesystem::path filename = cstr;
 
 void
 test01()
@@ -34,6 +35,13 @@ test01()
   VERIFY( fb.is_open() );
 }
 
+void
+test02() // compile-only
+{
+  std::filebuf fb;
+  fb.open(cstr, std::ios::in);	// PR libstdc++/83025
+}
+
 int
 main()
 {
diff --git a/libstdc++-v3/testsuite/27_io/basic_fstream/cons/char/path.cc b/libstdc++-v3/testsuite/27_io/basic_fstream/cons/char/path.cc
index 51337eb..079ebe2 100644
--- a/libstdc++-v3/testsuite/27_io/basic_fstream/cons/char/path.cc
+++ b/libstdc++-v3/testsuite/27_io/basic_fstream/cons/char/path.cc
@@ -40,10 +40,14 @@ test02()
   VERIFY( f.is_open() );
 }
 
+using std::is_constructible_v;
+// PR libstdc++/83025
+static_assert(is_constructible_v<std::fstream, char*>);
+static_assert(is_constructible_v<std::fstream, char*, std::ios::openmode>);
+
 int
 main()
 {
   test01();
   test02();
-  return 0;
 }
diff --git a/libstdc++-v3/testsuite/27_io/basic_fstream/open/char/path.cc b/libstdc++-v3/testsuite/27_io/basic_fstream/open/char/path.cc
index 8d0127b..297c897 100644
--- a/libstdc++-v3/testsuite/27_io/basic_fstream/open/char/path.cc
+++ b/libstdc++-v3/testsuite/27_io/basic_fstream/open/char/path.cc
@@ -24,7 +24,8 @@
 #include <filesystem>
 #include <testsuite_hooks.h>
 
-const std::filesystem::path filename = "ofstream_members-1.tst";
+char cstr[] = "filebuf_members-1.tst";
+const std::filesystem::path filename = cstr;
 
 void
 test01()
@@ -42,6 +43,14 @@ test02()
   VERIFY( f.is_open() );
 }
 
+void
+test03() // compile-only
+{
+  std::fstream f;
+  f.open(cstr);				    // PR libstdc++/83025
+  f.open(cstr, std::ios::in|std::ios::out); // PR libstdc++/83025
+}
+
 int
 main()
 {
diff --git a/libstdc++-v3/testsuite/27_io/basic_ifstream/cons/char/path.cc b/libstdc++-v3/testsuite/27_io/basic_ifstream/cons/char/path.cc
index a0de4ba..4265149 100644
--- a/libstdc++-v3/testsuite/27_io/basic_ifstream/cons/char/path.cc
+++ b/libstdc++-v3/testsuite/27_io/basic_ifstream/cons/char/path.cc
@@ -40,10 +40,14 @@ test02()
   VERIFY( f.is_open() );
 }
 
+using std::is_constructible_v;
+// PR libstdc++/83025
+static_assert(is_constructible_v<std::fstream, char*>);
+static_assert(is_constructible_v<std::fstream, char*, std::ios::openmode>);
+
 int
 main()
 {
   test01();
   test02();
-  return 0;
 }
diff --git a/libstdc++-v3/testsuite/27_io/basic_ifstream/open/char/path.cc b/libstdc++-v3/testsuite/27_io/basic_ifstream/open/char/path.cc
index 192e0fe..49b8c1e 100644
--- a/libstdc++-v3/testsuite/27_io/basic_ifstream/open/char/path.cc
+++ b/libstdc++-v3/testsuite/27_io/basic_ifstream/open/char/path.cc
@@ -24,7 +24,8 @@
 #include <filesystem>
 #include <testsuite_hooks.h>
 
-const std::filesystem::path filename = "ifstream_members-1.tst";
+char cstr[] = "filebuf_members-1.tst";
+const std::filesystem::path filename = cstr;
 
 void
 test01()
@@ -42,6 +43,14 @@ test02()
   VERIFY( f.is_open() );
 }
 
+void
+test03() // compile-only
+{
+  std::ifstream f;
+  f.open(cstr);		      // PR libstdc++/83025
+  f.open(cstr, std::ios::in); // PR libstdc++/83025
+}
+
 int
 main()
 {
diff --git a/libstdc++-v3/testsuite/27_io/basic_ofstream/cons/char/path.cc b/libstdc++-v3/testsuite/27_io/basic_ofstream/cons/char/path.cc
index c6b6b23..da88ff9 100644
--- a/libstdc++-v3/testsuite/27_io/basic_ofstream/cons/char/path.cc
+++ b/libstdc++-v3/testsuite/27_io/basic_ofstream/cons/char/path.cc
@@ -40,6 +40,11 @@ test02()
   VERIFY( f.is_open() );
 }
 
+using std::is_constructible_v;
+// PR libstdc++/83025
+static_assert(is_constructible_v<std::fstream, char*>);
+static_assert(is_constructible_v<std::fstream, char*, std::ios::openmode>);
+
 int
 main()
 {
diff --git a/libstdc++-v3/testsuite/27_io/basic_ofstream/open/char/path.cc b/libstdc++-v3/testsuite/27_io/basic_ofstream/open/char/path.cc
index 38078c9..4bbace2 100644
--- a/libstdc++-v3/testsuite/27_io/basic_ofstream/open/char/path.cc
+++ b/libstdc++-v3/testsuite/27_io/basic_ofstream/open/char/path.cc
@@ -24,7 +24,8 @@
 #include <filesystem>
 #include <testsuite_hooks.h>
 
-const std::filesystem::path filename = "ofstream_members-1.tst";
+char cstr[] = "filebuf_members-1.tst";
+const std::filesystem::path filename = cstr;
 
 void
 test01()
@@ -42,10 +43,17 @@ test02()
   VERIFY( f.is_open() );
 }
 
+void
+test03() // compile-only
+{
+  std::ofstream f;
+  f.open(cstr);			// PR libstdc++/83025
+  f.open(cstr, std::ios::out);	// PR libstdc++/83025
+}
+
 int
 main()
 {
   test01();
   test02();
-  return 0;
 }