[libc++] Introduce a setting to remove fstream from the library

ldionne · ldionne · commit af8c49dc1ec4 · 2022-11-20T10:51:32.000-05:00
This allows porting the library to platforms that are able to support <iostream> but that do not have a notion of a filesystem, and where it hence doesn't make sense to support std::fstream (and never will). Also, remove reliance on <fstream> in various tests that didn't actually need it. Differential Revision: https://reviews.llvm.org/D138327
diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
@@ -84,6 +84,8 @@ option(LIBCXX_ENABLE_LOCALIZATION
    the C locale API (e.g. embedded). When localization is not supported,
    several parts of the library will be disabled: <iostream>, <regex>, <locale>
    will be completely unusable, and other parts may be only partly available." ON)
+option(LIBCXX_ENABLE_FSTREAM
+   "Whether to include support for <fstream>." ON) # TODO: Consider rolling that into LIBCXX_ENABLE_FILESYSTEM
 option(LIBCXX_ENABLE_UNICODE
   "Whether to include support for Unicode in the library. Disabling Unicode can
    be useful when porting to platforms that don't support UTF-8 encoding (e.g.
@@ -860,6 +862,7 @@ config_define_if(LIBCXX_ENABLE_PARALLEL_ALGORITHMS _LIBCPP_HAS_PARALLEL_ALGORITH
 config_define_if_not(LIBCXX_ENABLE_FILESYSTEM _LIBCPP_HAS_NO_FILESYSTEM_LIBRARY)
 config_define_if_not(LIBCXX_ENABLE_RANDOM_DEVICE _LIBCPP_HAS_NO_RANDOM_DEVICE)
 config_define_if_not(LIBCXX_ENABLE_LOCALIZATION _LIBCPP_HAS_NO_LOCALIZATION)
+config_define_if_not(LIBCXX_ENABLE_FSTREAM _LIBCPP_HAS_NO_FSTREAM)
 config_define_if_not(LIBCXX_ENABLE_UNICODE _LIBCPP_HAS_NO_UNICODE)
 config_define_if_not(LIBCXX_ENABLE_WIDE_CHARACTERS _LIBCPP_HAS_NO_WIDE_CHARACTERS)
 config_define_if_not(LIBCXX_ENABLE_VENDOR_AVAILABILITY_ANNOTATIONS _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
diff --git a/libcxx/cmake/caches/Generic-no-fstream.cmake b/libcxx/cmake/caches/Generic-no-fstream.cmake
@@ -0,0 +1 @@
+set(LIBCXX_ENABLE_FSTREAM OFF CACHE BOOL "")
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
@@ -838,7 +838,7 @@ set(files
   wctype.h
   )
 
-foreach(feature LIBCXX_ENABLE_FILESYSTEM LIBCXX_ENABLE_LOCALIZATION LIBCXX_ENABLE_THREADS LIBCXX_ENABLE_WIDE_CHARACTERS)
+foreach(feature LIBCXX_ENABLE_FILESYSTEM LIBCXX_ENABLE_LOCALIZATION LIBCXX_ENABLE_FSTREAM LIBCXX_ENABLE_THREADS LIBCXX_ENABLE_WIDE_CHARACTERS)
   if (NOT ${${feature}})
     set(requires_${feature} "requires LIBCXX_CONFIGURED_WITHOUT_SUPPORT_FOR_THIS_HEADER")
   endif()
diff --git a/libcxx/include/__config_site.in b/libcxx/include/__config_site.in
@@ -28,6 +28,7 @@
 #cmakedefine _LIBCPP_HAS_PARALLEL_ALGORITHMS
 #cmakedefine _LIBCPP_HAS_NO_RANDOM_DEVICE
 #cmakedefine _LIBCPP_HAS_NO_LOCALIZATION
+#cmakedefine _LIBCPP_HAS_NO_FSTREAM
 #cmakedefine _LIBCPP_HAS_NO_WIDE_CHARACTERS
 #cmakedefine01 _LIBCPP_ENABLE_ASSERTIONS_DEFAULT
 #cmakedefine _LIBCPP_ENABLE_DEBUG_MODE
diff --git a/libcxx/include/fstream b/libcxx/include/fstream
@@ -210,6 +210,8 @@ _LIBCPP_PUSH_MACROS
 #  define _LIBCPP_HAS_NO_OFF_T_FUNCTIONS
 #endif
 
+#if !defined(_LIBCPP_HAS_NO_FSTREAM)
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 template <class _CharT, class _Traits>
@@ -1742,6 +1744,8 @@ extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_filebuf<char>;
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_HAS_NO_FSTREAM
+
 _LIBCPP_POP_MACROS
 
 #if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
@@ -855,6 +855,7 @@ module std [system] {
   }
   module fstream {
     @requires_LIBCXX_ENABLE_LOCALIZATION@
+    @requires_LIBCXX_ENABLE_FSTREAM@
     header "fstream"
     export *
   }
diff --git a/libcxx/src/ios.instantiations.cpp b/libcxx/src/ios.instantiations.cpp
@@ -36,9 +36,12 @@ template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_stringbuf<char>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_stringstream<char>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ostringstream<char>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_istringstream<char>;
+
+#ifndef _LIBCPP_HAS_NO_FSTREAM
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ifstream<char>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ofstream<char>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_filebuf<char>;
+#endif
 
 // Add more here if needed...
 
diff --git a/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp b/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp
@@ -325,7 +325,7 @@ int main(int, char**) { return 0; }
 #endif
 
 // RUN: %{build} -DTEST_51
-#if defined(TEST_51) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if defined(TEST_51) && !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #   include <fstream>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
diff --git a/libcxx/test/libcxx/clang_tidy.sh.cpp b/libcxx/test/libcxx/clang_tidy.sh.cpp
@@ -98,7 +98,7 @@ END-SCRIPT
 #include <float.h>
 #include <format>
 #include <forward_list>
-#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #   include <fstream>
 #endif
 #include <functional>
diff --git a/libcxx/test/libcxx/double_include.sh.cpp b/libcxx/test/libcxx/double_include.sh.cpp
@@ -100,7 +100,7 @@ END-SCRIPT
 #include <float.h>
 #include <format>
 #include <forward_list>
-#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #   include <fstream>
 #endif
 #include <functional>
diff --git a/libcxx/test/libcxx/min_max_macros.compile.pass.cpp b/libcxx/test/libcxx/min_max_macros.compile.pass.cpp
@@ -151,7 +151,7 @@ TEST_MACROS();
 TEST_MACROS();
 #include <forward_list>
 TEST_MACROS();
-#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #   include <fstream>
 TEST_MACROS();
 #endif
diff --git a/libcxx/test/libcxx/modules_include.sh.cpp b/libcxx/test/libcxx/modules_include.sh.cpp
@@ -251,7 +251,7 @@ END-SCRIPT
 #include <forward_list>
 #endif
 // RUN: %{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_51
-#if defined(TEST_51) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if defined(TEST_51) && !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #include <fstream>
 #endif
 // RUN: %{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_52
diff --git a/libcxx/test/libcxx/nasty_macros.compile.pass.cpp b/libcxx/test/libcxx/nasty_macros.compile.pass.cpp
@@ -219,7 +219,7 @@ END-SCRIPT
 #include <float.h>
 #include <format>
 #include <forward_list>
-#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #   include <fstream>
 #endif
 #include <functional>
diff --git a/libcxx/test/libcxx/no_assert_include.compile.pass.cpp b/libcxx/test/libcxx/no_assert_include.compile.pass.cpp
@@ -97,7 +97,7 @@ END-SCRIPT
 #include <float.h>
 #include <format>
 #include <forward_list>
-#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #   include <fstream>
 #endif
 #include <functional>
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/seekoff.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/seekoff.pass.cpp
@@ -13,8 +13,6 @@
 // pos_type seekpos(pos_type sp,
 //                  ios_base::openmode which = ios_base::in | ios_base::out);
 
-// FILE_DEPENDENCIES: underflow.dat
-
 #include <fstream>
 #include <cassert>
 
diff --git a/libcxx/test/std/input.output/file.streams/lit.local.cfg b/libcxx/test/std/input.output/file.streams/lit.local.cfg
@@ -1,3 +1,6 @@
 # All non-trivial uses of iostreams require localization support
 if 'no-localization' in config.available_features:
   config.unsupported = True
+
+if 'no-fstream' in config.available_features:
+  config.unsupported = True
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/xsputn.PR14074.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/xsputn.PR14074.pass.cpp
@@ -17,6 +17,8 @@
 // basic_streambuf, but I can't seem to reproduce without going through one
 // of its derived classes.
 
+// UNSUPPORTED: no-fstream
+
 #include <cassert>
 #include <cstddef>
 #include <cstdio>
diff --git a/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/overflow.pass.cpp b/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/overflow.pass.cpp
@@ -19,9 +19,10 @@
 // XFAIL: no-wide-characters
 
 #include <locale>
+#include <cassert>
 #include <codecvt>
 #include <fstream>
-#include <cassert>
+#include <sstream>
 
 #include "test_macros.h"
 
@@ -46,62 +47,73 @@ struct test_buf
 int main(int, char**)
 {
     {
-        std::ofstream bs("overflow.dat");
-        test_buf f(bs.rdbuf());
-        assert(f.pbase() == 0);
-        assert(f.pptr() == 0);
-        assert(f.epptr() == 0);
-        assert(f.overflow(L'a') == L'a');
-        assert(f.pbase() != 0);
-        assert(f.pptr() == f.pbase());
-        assert(f.epptr() - f.pbase() == 4095);
-    }
-    {
-        std::ifstream bs("overflow.dat");
-        test_buf f(bs.rdbuf());
-        assert(f.sgetc() == L'a');
-    }
-    std::remove("overflow.dat");
-    {
-        std::ofstream bs("overflow.dat");
-        test_buf f(bs.rdbuf());
-        f.pubsetbuf(0, 0);
-        assert(f.pbase() == 0);
-        assert(f.pptr() == 0);
-        assert(f.epptr() == 0);
-        assert(f.overflow('a') == 'a');
-        assert(f.pbase() == 0);
-        assert(f.pptr() == 0);
-        assert(f.epptr() == 0);
-    }
-    {
-        std::ifstream bs("overflow.dat");
-        test_buf f(bs.rdbuf());
-        assert(f.sgetc() == L'a');
+        std::string s;
+        {
+            std::ostringstream out;
+            test_buf f(out.rdbuf());
+            assert(f.pbase() == 0);
+            assert(f.pptr() == 0);
+            assert(f.epptr() == 0);
+            assert(f.overflow(L'a') == L'a');
+            assert(f.pbase() != 0);
+            assert(f.pptr() == f.pbase());
+            assert(f.epptr() - f.pbase() == 4095);
+            s = out.str();
+        }
+        {
+            std::istringstream in(s);
+            test_buf f(in.rdbuf());
+            assert(f.sgetc() == L'a');
+        }
     }
-    std::remove("overflow.dat");
     {
-        std::ofstream bs("overflow.dat");
-        test_buf f(bs.rdbuf());
-        assert(f.sputc(0x4E51) == 0x4E51);
-        assert(f.sputc(0x4E52) == 0x4E52);
-        assert(f.sputc(0x4E53) == 0x4E53);
+        std::string s;
+        {
+            std::ostringstream out;
+            test_buf f(out.rdbuf());
+            f.pubsetbuf(0, 0);
+            assert(f.pbase() == 0);
+            assert(f.pptr() == 0);
+            assert(f.epptr() == 0);
+            assert(f.overflow('a') == 'a');
+            assert(f.pbase() == 0);
+            assert(f.pptr() == 0);
+            assert(f.epptr() == 0);
+            s = out.str();
+        }
+        {
+            std::istringstream in(s);
+            test_buf f(in.rdbuf());
+            assert(f.sgetc() == L'a');
+        }
     }
+    // TODO: Move this to std::stringstream once https://llvm.org/PR59083 has been resolved
+#ifndef TEST_HAS_NO_FSTREAM
     {
-        std::ifstream f("overflow.dat");
-        assert(f.is_open());
-        assert(f.get() == 0xE4);
-        assert(f.get() == 0xB9);
-        assert(f.get() == 0x91);
-        assert(f.get() == 0xE4);
-        assert(f.get() == 0xB9);
-        assert(f.get() == 0x92);
-        assert(f.get() == 0xE4);
-        assert(f.get() == 0xB9);
-        assert(f.get() == 0x93);
-        assert(f.get() == -1);
+        {
+            std::ofstream bs("overflow.dat");
+            test_buf f(bs.rdbuf());
+            assert(f.sputc(0x4E51) == 0x4E51);
+            assert(f.sputc(0x4E52) == 0x4E52);
+            assert(f.sputc(0x4E53) == 0x4E53);
+        }
+        {
+            std::ifstream f("overflow.dat");
+            assert(f.is_open());
+            assert(f.get() == 0xE4);
+            assert(f.get() == 0xB9);
+            assert(f.get() == 0x91);
+            assert(f.get() == 0xE4);
+            assert(f.get() == 0xB9);
+            assert(f.get() == 0x92);
+            assert(f.get() == 0xE4);
+            assert(f.get() == 0xB9);
+            assert(f.get() == 0x93);
+            assert(f.get() == -1);
+        }
+        std::remove("overflow.dat");
     }
-    std::remove("overflow.dat");
+#endif // TEST_HAS_NO_FSTREAM
 
-  return 0;
+    return 0;
 }
diff --git a/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/pbackfail.pass.cpp b/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/pbackfail.pass.cpp
@@ -6,8 +6,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-// FILE_DEPENDENCIES: underflow.dat
-
 // <locale>
 
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DISABLE_DEPRECATION_WARNINGS
@@ -21,11 +19,9 @@
 // XFAIL: no-wide-characters
 
 #include <locale>
-#include <codecvt>
-#include <fstream>
 #include <cassert>
-
-#include "test_macros.h"
+#include <codecvt>
+#include <sstream>
 
 struct test_buf
     : public std::wbuffer_convert<std::codecvt_utf8<wchar_t> >
@@ -47,16 +43,17 @@ struct test_buf
 
 int main(int, char**)
 {
+    std::string const s = "123456789";
     {
-        std::ifstream bs("underflow.dat");
-        test_buf f(bs.rdbuf());
+        std::istringstream in(s);
+        test_buf f(in.rdbuf());
         assert(f.sbumpc() == L'1');
         assert(f.sgetc() == L'2');
         assert(f.pbackfail(L'a') == test_buf::traits_type::eof());
     }
     {
-        std::fstream bs("underflow.dat");
-        test_buf f(bs.rdbuf());
+        std::istringstream in(s);
+        test_buf f(in.rdbuf());
         assert(f.sbumpc() == L'1');
         assert(f.sgetc() == L'2');
         assert(f.pbackfail(L'a') == test_buf::traits_type::eof());
diff --git a/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/seekoff.pass.cpp b/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/seekoff.pass.cpp
@@ -21,13 +21,14 @@
 
 // XFAIL: no-wide-characters
 
+// TODO: Avoid using <fstream> in this test.
+// XFAIL: no-fstream
+
 #include <locale>
 #include <codecvt>
 #include <fstream>
 #include <cassert>
 
-#include "test_macros.h"
-
 class test_codecvt
     : public std::codecvt<wchar_t, char, std::mbstate_t>
 {
diff --git a/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/test.pass.cpp b/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/test.pass.cpp
diff --git a/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/underflow.dat b/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/underflow.dat
diff --git a/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/underflow.pass.cpp b/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/underflow.pass.cpp
diff --git a/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/underflow_utf8.dat b/libcxx/test/std/localization/locales/locale.convenience/conversions/conversions.buffer/underflow_utf8.dat
diff --git a/libcxx/test/std/utilities/charconv/charconv.msvc/test.cpp b/libcxx/test/std/utilities/charconv/charconv.msvc/test.cpp
diff --git a/libcxx/test/support/test_macros.h b/libcxx/test/support/test_macros.h
diff --git a/libcxx/utils/ci/buildkite-pipeline.yml b/libcxx/utils/ci/buildkite-pipeline.yml
diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
diff --git a/libcxx/utils/generate_header_tests.py b/libcxx/utils/generate_header_tests.py
diff --git a/libcxx/utils/libcxx/test/features.py b/libcxx/utils/libcxx/test/features.py

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+set(LIBCXX_ENABLE_FSTREAM OFF CACHE BOOL "")`
Original file line number	Diff line number	Diff line change
`@@ -838,7 +838,7 @@ set(files`
`838`	`838`	`wctype.h`
`839`	`839`	`)`
`840`	`840`
`841`		`-foreach(feature LIBCXX_ENABLE_FILESYSTEM LIBCXX_ENABLE_LOCALIZATION LIBCXX_ENABLE_THREADS LIBCXX_ENABLE_WIDE_CHARACTERS)`
	`841`	`+foreach(feature LIBCXX_ENABLE_FILESYSTEM LIBCXX_ENABLE_LOCALIZATION LIBCXX_ENABLE_FSTREAM LIBCXX_ENABLE_THREADS LIBCXX_ENABLE_WIDE_CHARACTERS)`
`842`	`842`	`if (NOT ${${feature}})`
`843`	`843`	`set(requires_${feature} "requires LIBCXX_CONFIGURED_WITHOUT_SUPPORT_FOR_THIS_HEADER")`
`844`	`844`	`endif()`
Original file line number	Diff line number	Diff line change
`@@ -855,6 +855,7 @@ module std [system] {`
`855`	`855`	`}`
`856`	`856`	`module fstream {`
`857`	`857`	`@requires_LIBCXX_ENABLE_LOCALIZATION@`
	`858`	`+ @requires_LIBCXX_ENABLE_FSTREAM@`
`858`	`859`	`header "fstream"`
`859`	`860`	`export *`
`860`	`861`	`}`