libstdc++: Deprecate useless <cxxx> compatibility headers for C++17

These headers make no sense for C++ programs, because they either define
different content to the corresponding <xxx.h> C header, or define
nothing at all in namespace std. They were all deprecated in C++17, so
add deprecation warnings to them, which can be disabled with
-Wno-deprecated. For C++20 and later these headers are no longer in the
standard at all, so compiling with _GLIBCXX_USE_DEPRECATED defined to 0
will give an error when they are included.

Because #warning is non-standard before C++23 we need to use pragmas to
ignore -Wc++23-extensions for the -Wsystem-headers -pedantic case.

One g++ test needs adjustment because it includes <ciso646>, but that
can be made conditional on the __cplusplus value without any reduction
in test coverage.

For the library tests, consolidate the std_c++0x_neg.cc XFAIL tests into
the macros.cc test, using dg-error with a { target c++98_only }
selector. This avoids having two separate test files, one for C++98 and
one for everything later. Also add tests for the <xxx.h> headers to
ensure that they behave as expected and don't give deprecated warnings.

libstdc++-v3/ChangeLog:

	* doc/xml/manual/evolution.xml: Document deprecations.
	* doc/html/*: Regenerate.
	* include/c_compatibility/complex.h (_GLIBCXX_COMPLEX_H): Move
	include guard to start of file. Include <complex> directly
	instead of <ccomplex>.
	* include/c_compatibility/tgmath.h: Include <cmath> and
	<complex> directly, instead of <ctgmath>.
	* include/c_global/ccomplex: Add deprecated #warning for C++17
	and #error for C++20 if _GLIBCXX_USE_DEPRECATED == 0.
	* include/c_global/ciso646: Likewise.
	* include/c_global/cstdalign: Likewise.
	* include/c_global/cstdbool: Likewise.
	* include/c_global/ctgmath: Likewise.
	* include/c_std/ciso646: Likewise.
	* include/precompiled/stdc++.h: Do not include ccomplex,
	ciso646, cstdalign, cstdbool, or ctgmath in C++17 and later.
	* testsuite/18_support/headers/cstdalign/macros.cc: Check for
	warnings and errors for unsupported dialects.
	* testsuite/18_support/headers/cstdbool/macros.cc: Likewise.
	* testsuite/26_numerics/headers/ctgmath/complex.cc: Likewise.
	* testsuite/27_io/objects/char/1.cc: Do not include <ciso646>.
	* testsuite/27_io/objects/wchar_t/1.cc: Likewise.
	* testsuite/18_support/headers/cstdbool/std_c++0x_neg.cc: Removed.
	* testsuite/18_support/headers/cstdalign/std_c++0x_neg.cc: Removed.
	* testsuite/26_numerics/headers/ccomplex/std_c++0x_neg.cc: Removed.
	* testsuite/26_numerics/headers/ctgmath/std_c++0x_neg.cc: Removed.
	* testsuite/18_support/headers/ciso646/macros.cc: New test.
	* testsuite/18_support/headers/ciso646/macros.h.cc: New test.
	* testsuite/18_support/headers/cstdbool/macros.h.cc: New test.
	* testsuite/26_numerics/headers/ccomplex/complex.cc: New test.
	* testsuite/26_numerics/headers/ccomplex/complex.h.cc: New test.
	* testsuite/26_numerics/headers/ctgmath/complex.h.cc: New test.

gcc/testsuite/ChangeLog:

	* g++.old-deja/g++.other/headers1.C: Do not include ciso646 for
	C++17 and later.

16 files changed, 199 insertions, 109 deletions

diff --git a/libstdc++-v3/testsuite/18_support/headers/ciso646/macros.cc b/libstdc++-v3/testsuite/18_support/headers/ciso646/macros.cc
new file mode 100644
index 0000000..ab3a041
--- /dev/null
+++ b/libstdc++-v3/testsuite/18_support/headers/ciso646/macros.cc
@@ -0,0 +1,51 @@
+// { dg-options "-D_GLIBCXX_USE_DEPRECATED=0 -Wdeprecated -fno-operator-names" }
+// { dg-do preprocess }
+
+#include <ciso646>
+
+// { dg-warning "deprecated" "" { target c++17_only } 0 }
+// { dg-error "not a standard header" "" { target c++20 } 0 }
+
+#ifdef and
+# error "The header <ciso646> defines a macro named and"
+#endif
+
+#ifdef and_eq
+# error "The header <ciso646> defines a macro named and_eq"
+#endif
+
+#ifdef bitand
+# error "The header <ciso646> defines a macro named bitand"
+#endif
+
+#ifdef bitor
+# error "The header <ciso646> defines a macro named bitor"
+#endif
+
+#ifdef compl
+# error "The header <ciso646> defines a macro named compl"
+#endif
+
+#ifdef not
+# error "The header <ciso646> defines a macro named not"
+#endif
+
+#ifdef not_eq
+# error "The header <ciso646> defines a macro named not_eq"
+#endif
+
+#ifdef or
+# error "The header <ciso646> defines a macro named or"
+#endif
+
+#ifdef or_eq
+# error "The header <ciso646> defines a macro named or_eq"
+#endif
+
+#ifdef xor
+# error "The header <ciso646> defines a macro named xor"
+#endif
+
+#ifdef xor_eq
+# error "The header <ciso646> defines a macro named xor_eq"
+#endif
diff --git a/libstdc++-v3/testsuite/18_support/headers/ciso646/macros.h.cc b/libstdc++-v3/testsuite/18_support/headers/ciso646/macros.h.cc
new file mode 100644
index 0000000..a70c18de
--- /dev/null
+++ b/libstdc++-v3/testsuite/18_support/headers/ciso646/macros.h.cc
@@ -0,0 +1,49 @@
+// { dg-options "-D_GLIBCXX_USE_DEPRECATED=0 -Wdeprecated -fno-operator-names" }
+// { dg-do preprocess }
+// { dg-bogus "deprecated" "C++17 deprecated <ciso646> but not <iso646.h>" }
+
+#include <iso646.h>
+
+#ifdef and
+# error "The header <iso646.h> defines a macro named and"
+#endif
+
+#ifdef and_eq
+# error "The header <iso646.h> defines a macro named and_eq"
+#endif
+
+#ifdef bitand
+# error "The header <iso646.h> defines a macro named bitand"
+#endif
+
+#ifdef bitor
+# error "The header <iso646.h> defines a macro named bitor"
+#endif
+
+#ifdef compl
+# error "The header <iso646.h> defines a macro named compl"
+#endif
+
+#ifdef not
+# error "The header <iso646.h> defines a macro named not"
+#endif
+
+#ifdef not_eq
+# error "The header <iso646.h> defines a macro named not_eq"
+#endif
+
+#ifdef or
+# error "The header <iso646.h> defines a macro named or"
+#endif
+
+#ifdef or_eq
+# error "The header <iso646.h> defines a macro named or_eq"
+#endif
+
+#ifdef xor
+# error "The header <iso646.h> defines a macro named xor"
+#endif
+
+#ifdef xor_eq
+# error "The header <iso646.h> defines a macro named xor_eq"
+#endif
diff --git a/libstdc++-v3/testsuite/18_support/headers/cstdalign/macros.cc b/libstdc++-v3/testsuite/18_support/headers/cstdalign/macros.cc
index c50c921..793cd26 100644
--- a/libstdc++-v3/testsuite/18_support/headers/cstdalign/macros.cc
+++ b/libstdc++-v3/testsuite/18_support/headers/cstdalign/macros.cc
@@ -1,8 +1,13 @@
-// { dg-options "-D_GLIBCXX_USE_DEPRECATED=1 -Wno-deprecated" }
-// { dg-do preprocess { target c++11 } }
+// { dg-options "-D_GLIBCXX_USE_DEPRECATED=0 -Wdeprecated" }
+// { dg-do preprocess }
 
 #include <cstdalign>
 
+// { dg-error "ISO C.. 2011" "" { target c++98_only } 0 }
+// { dg-warning "deprecated" "" { target c++17_only } 0 }
+// { dg-error "not a standard header" "" { target c++20 } 0 }
+
+#if __cplusplus >= 201103L
 #ifndef __alignas_is_defined
 # error "The header <cstdalign> fails to define a macro named  __alignas_is_defined"
 #elif __alignas_is_defined != 1
@@ -22,3 +27,4 @@
 #ifdef alignof
 # error "The header <cstdalign> defines a macro named alignof"
 #endif
+#endif
diff --git a/libstdc++-v3/testsuite/18_support/headers/cstdalign/macros.h.cc b/libstdc++-v3/testsuite/18_support/headers/cstdalign/macros.h.cc
new file mode 100644
index 0000000..78f41ae
--- /dev/null
+++ b/libstdc++-v3/testsuite/18_support/headers/cstdalign/macros.h.cc
@@ -0,0 +1,25 @@
+// { dg-options "-D_GLIBCXX_USE_DEPRECATED=0 -Wdeprecated" }
+// { dg-do preprocess { target c++11 } }
+// { dg-bogus "deprecated" "C++17 deprecated <cstdalign> but not <stdalign.h>" }
+
+#include <stdalign.h>
+
+#ifndef __alignas_is_defined
+# error "The header <stdalign.h> fails to define a macro named  __alignas_is_defined"
+#elif __alignas_is_defined != 1
+# error "__alignas_is_defined is not defined to 1 in <stdalign.h>"
+#endif
+
+#ifndef __alignof_is_defined
+# error "The header <stdalign.h> fails to define a macro named __alignof_is_defined"
+#elif __alignof_is_defined != 1
+# error "__alignof_is_defined is not defined to 1 in <stdalign.h>"
+#endif
+
+#ifdef alignas
+# error "The header <stdalign.h> defines a macro named alignas"
+#endif
+
+#ifdef alignof
+# error "The header <stdalign.h> defines a macro named alignof"
+#endif
diff --git a/libstdc++-v3/testsuite/18_support/headers/cstdalign/std_c++0x_neg.cc b/libstdc++-v3/testsuite/18_support/headers/cstdalign/std_c++0x_neg.cc
deleted file mode 100644
index 14694f0..0000000
--- a/libstdc++-v3/testsuite/18_support/headers/cstdalign/std_c++0x_neg.cc
+++ /dev/null
@@ -1,24 +0,0 @@
-// { dg-options "-std=gnu++98" }
-// { dg-do compile { target c++98_only } }
-
-// Copyright (C) 2011-2024 Free Software Foundation, Inc.
-//
-// This file is part of the GNU ISO C++ Library.  This library is free
-// software; you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the
-// Free Software Foundation; either version 3, or (at your option)
-// any later version.
-
-// This library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-
-// You should have received a copy of the GNU General Public License along
-// with this library; see the file COPYING3.  If not see
-// <http://www.gnu.org/licenses/>.
-
-#include <cstdalign>
-
-// { dg-error "ISO C.. 2011" "" { target *-*-* } 32 }
-
diff --git a/libstdc++-v3/testsuite/18_support/headers/cstdbool/macros.cc b/libstdc++-v3/testsuite/18_support/headers/cstdbool/macros.cc
index e0afc26e..658a02a 100644
--- a/libstdc++-v3/testsuite/18_support/headers/cstdbool/macros.cc
+++ b/libstdc++-v3/testsuite/18_support/headers/cstdbool/macros.cc
@@ -1,4 +1,5 @@
-// { dg-do compile { target c++11 } }
+// { dg-options "-D_GLIBCXX_USE_DEPRECATED=0 -Wdeprecated" }
+// { dg-do preprocess }
 
 // Copyright (C) 2012-2024 Free Software Foundation, Inc.
 //
@@ -19,6 +20,11 @@
 
 #include <cstdbool>
 
+// { dg-error "ISO C.. 2011" "" { target c++98_only } 0 }
+// { dg-warning "deprecated" "" { target c++17_only } 0 }
+// { dg-error "not a standard header" "" { target c++20 } 0 }
+
+#if __cplusplus >= 201103L
 #ifndef __bool_true_false_are_defined
 # error "The header <cstdbool> fails to define a macro named __bool_true_false_are_defined"
 #endif
@@ -34,3 +40,4 @@
 #ifdef false
 # error "The header <cstdbool> defines a macro named false"
 #endif
+#endif
diff --git a/libstdc++-v3/testsuite/18_support/headers/cstdbool/macros.h.cc b/libstdc++-v3/testsuite/18_support/headers/cstdbool/macros.h.cc
new file mode 100644
index 0000000..a3c0f9a
--- /dev/null
+++ b/libstdc++-v3/testsuite/18_support/headers/cstdbool/macros.h.cc
@@ -0,0 +1,21 @@
+// { dg-options "-D_GLIBCXX_USE_DEPRECATED=0 -Wdeprecated" }
+// { dg-do preprocess { target c++11 } }
+// { dg-bogus "deprecated" "C++17 deprecated <cstdbool> but not <stdbool.h>" }
+
+#include <stdbool.h>
+
+#ifndef __bool_true_false_are_defined
+# error "The header <stdbool.h> fails to define a macro named __bool_true_false_are_defined"
+#endif
+
+#ifdef bool
+# error "The header <stdbool.h> defines a macro named bool"
+#endif
+
+#ifdef true
+# error "The header <stdbool.h> defines a macro named true"
+#endif
+
+#ifdef false
+# error "The header <stdbool.h> defines a macro named false"
+#endif
diff --git a/libstdc++-v3/testsuite/18_support/headers/cstdbool/std_c++0x_neg.cc b/libstdc++-v3/testsuite/18_support/headers/cstdbool/std_c++0x_neg.cc
deleted file mode 100644
index 5b8c568..0000000
--- a/libstdc++-v3/testsuite/18_support/headers/cstdbool/std_c++0x_neg.cc
+++ /dev/null
@@ -1,26 +0,0 @@
-// { dg-options "-std=gnu++98" }
-// { dg-do compile { target c++98_only } }
-
-// Copyright (C) 2007-2024 Free Software Foundation, Inc.
-//
-// This file is part of the GNU ISO C++ Library.  This library is free
-// software; you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the
-// Free Software Foundation; either version 3, or (at your option)
-// any later version.
-
-// This library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-
-// You should have received a copy of the GNU General Public License along
-// with this library; see the file COPYING3.  If not see
-// <http://www.gnu.org/licenses/>.
-
-#include <cstdbool>
-
-// { dg-error "ISO C.. 2011" "" { target *-*-* } 32 }
-
-
-
diff --git a/libstdc++-v3/testsuite/26_numerics/headers/ccomplex/complex.cc b/libstdc++-v3/testsuite/26_numerics/headers/ccomplex/complex.cc
new file mode 100644
index 0000000..d6c3378
--- /dev/null
+++ b/libstdc++-v3/testsuite/26_numerics/headers/ccomplex/complex.cc
@@ -0,0 +1,10 @@
+// { dg-options "-D_GLIBCXX_USE_DEPRECATED=0 -Wdeprecated" }
+// { dg-do compile }
+
+#include <ccomplex>
+
+std::complex<double> d;
+
+// { dg-error "ISO C.. 2011" "" { target c++98_only } 0 }
+// { dg-warning "deprecated" "" { target c++17_only } 0 }
+// { dg-error "not a standard header" "" { target c++20 } 0 }
diff --git a/libstdc++-v3/testsuite/26_numerics/headers/ccomplex/complex.h.cc b/libstdc++-v3/testsuite/26_numerics/headers/ccomplex/complex.h.cc
new file mode 100644
index 0000000..318b78e
--- /dev/null
+++ b/libstdc++-v3/testsuite/26_numerics/headers/ccomplex/complex.h.cc
@@ -0,0 +1,10 @@
+// { dg-options "-D_GLIBCXX_USE_DEPRECATED=0 -Wdeprecated" }
+// { dg-do compile }
+// { dg-bogus "deprecated" "C++17 deprecated <ccomplex> but not <complex.h>" }
+
+#include <complex.h>
+
+#if __cplusplus < 201103L
+# undef complex
+#endif
+std::complex<double> d; // { dg-error "does not name a template" "" { target c++98_only } 0 }
diff --git a/libstdc++-v3/testsuite/26_numerics/headers/ccomplex/std_c++0x_neg.cc b/libstdc++-v3/testsuite/26_numerics/headers/ccomplex/std_c++0x_neg.cc
deleted file mode 100644
index 16c623b..0000000
--- a/libstdc++-v3/testsuite/26_numerics/headers/ccomplex/std_c++0x_neg.cc
+++ /dev/null
@@ -1,26 +0,0 @@
-// { dg-options "-std=gnu++98" }
-// { dg-do compile { target c++98_only } }
-
-// Copyright (C) 2007-2024 Free Software Foundation, Inc.
-//
-// This file is part of the GNU ISO C++ Library.  This library is free
-// software; you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the
-// Free Software Foundation; either version 3, or (at your option)
-// any later version.
-
-// This library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-
-// You should have received a copy of the GNU General Public License along
-// with this library; see the file COPYING3.  If not see
-// <http://www.gnu.org/licenses/>.
-
-#include <ccomplex>
-
-// { dg-error "ISO C.. 2011" "" { target *-*-* } 32 }
-
-
-
diff --git a/libstdc++-v3/testsuite/26_numerics/headers/ctgmath/complex.cc b/libstdc++-v3/testsuite/26_numerics/headers/ctgmath/complex.cc
index a2c4a55..ef2bbd0 100644
--- a/libstdc++-v3/testsuite/26_numerics/headers/ctgmath/complex.cc
+++ b/libstdc++-v3/testsuite/26_numerics/headers/ctgmath/complex.cc
@@ -15,8 +15,13 @@
 // with this library; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-// { dg-do compile { target c++11 } }
+// { dg-options "-D_GLIBCXX_USE_DEPRECATED=0 -Wdeprecated" }
+// { dg-do compile }
 
 #include <ctgmath>
 
-std::complex<double> d;
+std::complex<double> d; // { dg-error "does not name a template" "" { target c++98_only } 0 }
+
+// { dg-error "ISO C.. 2011" "" { target c++98_only } 0 }
+// { dg-warning "deprecated" "" { target c++17_only } 0 }
+// { dg-error "not a standard header" "" { target c++20 } 0 }
diff --git a/libstdc++-v3/testsuite/26_numerics/headers/ctgmath/complex.h.cc b/libstdc++-v3/testsuite/26_numerics/headers/ctgmath/complex.h.cc
new file mode 100644
index 0000000..fd6847b
--- /dev/null
+++ b/libstdc++-v3/testsuite/26_numerics/headers/ctgmath/complex.h.cc
@@ -0,0 +1,10 @@
+// { dg-options "-D_GLIBCXX_USE_DEPRECATED=0 -Wdeprecated" }
+// { dg-do compile }
+// { dg-bogus "deprecated" "C++17 deprecated <ctgmath> but not <tgmath.h>" }
+
+#include <tgmath.h>
+
+#if __cplusplus < 201103L
+# undef complex
+#endif
+std::complex<double> d; // { dg-error "does not name a template" "" { target c++98_only } 0 }
diff --git a/libstdc++-v3/testsuite/26_numerics/headers/ctgmath/std_c++0x_neg.cc b/libstdc++-v3/testsuite/26_numerics/headers/ctgmath/std_c++0x_neg.cc
deleted file mode 100644
index d693c8b..0000000
--- a/libstdc++-v3/testsuite/26_numerics/headers/ctgmath/std_c++0x_neg.cc
+++ /dev/null
@@ -1,26 +0,0 @@
-// { dg-options "-std=gnu++98" }
-// { dg-do compile { target c++98_only } }
-
-// Copyright (C) 2007-2024 Free Software Foundation, Inc.
-//
-// This file is part of the GNU ISO C++ Library.  This library is free
-// software; you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the
-// Free Software Foundation; either version 3, or (at your option)
-// any later version.
-
-// This library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-
-// You should have received a copy of the GNU General Public License along
-// with this library; see the file COPYING3.  If not see
-// <http://www.gnu.org/licenses/>.
-
-#include <ctgmath>
-
-// { dg-error "ISO C.. 2011" "" { target *-*-* } 32 }
-
-
-
diff --git a/libstdc++-v3/testsuite/27_io/objects/char/1.cc b/libstdc++-v3/testsuite/27_io/objects/char/1.cc
index 9fc9244..d50b388 100644
--- a/libstdc++-v3/testsuite/27_io/objects/char/1.cc
+++ b/libstdc++-v3/testsuite/27_io/objects/char/1.cc
@@ -53,7 +53,6 @@
 #include <cctype>
 #include <cerrno>
 #include <cfloat>
-#include <ciso646>
 #include <climits>
 #include <clocale>
 #include <cmath>
diff --git a/libstdc++-v3/testsuite/27_io/objects/wchar_t/1.cc b/libstdc++-v3/testsuite/27_io/objects/wchar_t/1.cc
index 23b2168..c2f3643 100644
--- a/libstdc++-v3/testsuite/27_io/objects/wchar_t/1.cc
+++ b/libstdc++-v3/testsuite/27_io/objects/wchar_t/1.cc
@@ -53,7 +53,6 @@
 #include <cctype>
 #include <cerrno>
 #include <cfloat>
-#include <ciso646>
 #include <climits>
 #include <clocale>
 #include <cmath>