libstdc++: Fix std::system_category().message(int) on mingw32 target

On the mingw32 target, std::system_category().message(int) uses
FormatMessage api to format error messages. When the error message
contains insert sequences, it is unsafe not to use the
FORMAT_MESSAGE_OGNORE_INSERTS flag, as seen at:
https://devblogs.microsoft.com/oldnewthing/20071128-00/?p=24353

The output of FormatMessage ends with "\r\n" and includes a Full stop
character used by the current thread's UI language. Now, we will remove
"\r\n" and any trailing '.' from the output in any language environment.

In the testsuite for std::system_category().message(int), we first
switch the thread UI language to en-US to meet expectations in any
language environment.

libstdc++-v3/ChangeLog:

	* src/c++11/system_error.cc (system_error_category) [_WIN32]:
	Use FormatMessageA function instead of FormatMessage macro.
	* testsuite/19_diagnostics/error_category/system_category.cc:
	Fix typo in __MINGW32__ macro name.  Adjust behavior on the
	mingw32 target.

diff --git a/libstdc++-v3/src/c++11/system_error.cc b/libstdc++-v3/src/c++11/system_error.cc
index 548c88fcfdea94aa8fe733d59ba805d504a278c1..851f51acd404ddf57c302ba439cdb3c0e281a5a3 100644 (file)
--- a/libstdc++-v3/src/c++11/system_error.cc
+++ b/libstdc++-v3/src/c++11/system_error.cc
@@ -161,22 +161,23 @@ namespace
 #if defined(_WIN32) && !defined(__CYGWIN__)
       char* buf = nullptr;
       auto len
-       = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM
-                       | FORMAT_MESSAGE_ALLOCATE_BUFFER,
-                       nullptr,
-                       i,
-                       LANG_USER_DEFAULT,
-                       reinterpret_cast<LPTSTR>(&buf),
-                       0,
-                       nullptr);
+       = FormatMessageA(FORMAT_MESSAGE_FROM_SYSTEM
+                        | FORMAT_MESSAGE_ALLOCATE_BUFFER
+                        | FORMAT_MESSAGE_IGNORE_INSERTS,
+                        nullptr,
+                        i,
+                        LANG_USER_DEFAULT,
+                        reinterpret_cast<LPTSTR>(&buf),
+                        0,
+                        nullptr);
       if (len > 0)
       {
        struct deleter {
          void operator()(void* p) const { ::LocalFree(p); }
        };
        std::unique_ptr<char[], deleter> guard(buf);
-       if (len > 3 && !__builtin_memcmp(buf + len - 3, ".\r\n", 3)) [[likely]]
-         len -= 3;
+       if (len > 2 && !__builtin_memcmp (buf + len - 2, "\r\n", 2)) [[likely]]
+         len -= 2 + (buf[len - 3] == '.');
        return string(buf, len);
       }
       return string("Unknown error code");

diff --git a/libstdc++-v3/testsuite/19_diagnostics/error_category/system_category.cc b/libstdc++-v3/testsuite/19_diagnostics/error_category/system_category.cc
index 250d34f9bb5eb2e428c5260def1804b545a8eca7..b314884ef698ef92945d3b03fc109949133b772c 100644 (file)
--- a/libstdc++-v3/testsuite/19_diagnostics/error_category/system_category.cc
+++ b/libstdc++-v3/testsuite/19_diagnostics/error_category/system_category.cc
@@ -21,6 +21,11 @@
 #include <locale>
 #include <testsuite_hooks.h>
 
+#if defined __MINGW32__ || defined __MINGW64__
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#endif
+
 void
 test01()
 {
@@ -34,7 +39,7 @@ test02()
   const std::error_category& cat = std::system_category();
   std::error_condition cond;
 
-#if defined __MING32__ || defined __MINGW64__
+#if defined __MINGW32__ || defined __MINGW64__
   cond = cat.default_error_condition(8); // ERROR_NOT_ENOUGH_MEMORY
   VERIFY( cond.value() == ENOMEM );
   VERIFY( cond.category() == std::generic_category() );
@@ -112,9 +117,17 @@ test03()
   // set "C" locale to get expected message
   auto loc = std::locale::global(std::locale::classic());
 
-#if defined __MING32__ || defined __MINGW64__
+#if defined __MINGW32__ || defined __MINGW64__
+  // On Windows, set thread preferred UI languages to "en-US"
+  // to get expected message
+  ULONG num_langs = 1;
+  SetThreadPreferredUILanguages(MUI_LANGUAGE_NAME, L"en-US\0", &num_langs);
+
   std::string msg = std::system_category().message(5); // ERROR_ACCESS_DENIED
-  VERIFY(msg == "Access denied");
+  // Windows returns "Access is denied" but Wine returns "Access denied".
+  VERIFY(msg == "Access is denied" || msg == "Access denied");
+
+  SetThreadPreferredUILanguages(MUI_RESET_FILTERS, nullptr, nullptr);
 #else
   std::string msg = std::system_category().message(EBADF);
   VERIFY( msg.find("file") != std::string::npos );