Updates HSYS_GOTO_ERROR to emit GetLastError() values on Win32

release_docs/RELEASE.txt

@@ -384,6 +384,33 @@ New Features
 
     Library:
     --------
+    - HSYS_GOTO_ERROR now emits the results of GetLastError() on Windows
+
+      HSYS_GOTO_ERROR is an internal macro that is used to produce error
+      messages when system calls fail. These strings include errno and the
+      the associated strerror() value, which are not particularly useful
+      when a Win32 API call fails.
+
+      On Windows, this macro has been updated to include the result of
+      GetLastError(). When a system call fails on Windows, usually only
+      one of errno and GetLastError() will be useful, however we emit both
+      for the user to parse. The Windows error message is not emitted as
+      it would be awkward to free the FormatMessage() buffer given the
+      existing HDF5 error framework. Users will have to look up the error
+      codes in MSDN.
+
+      The format string on Windows has been changed from:
+
+          "%s, errno = %d, error message = '%s'"
+
+      to:
+
+          "%s, errno = %d, error message = '%s', Win32 GetLastError() = %"PRIu32""
+
+      for those inclined to parse it for error values.
+
+        (DER - 2021/03/21)
+
     - File locking now works on Windows
 
       Since version 1.10.0, the HDF5 library has used a file locking scheme
@@ -400,7 +427,6 @@ New Features
 
         (DER - 2021/03/19, HDFFV-10191)
 
-
     - H5Epush_ret() now requires a trailing semicolon
 
         H5Epush_ret() is a function-like macro that has been changed to

src/H5Eprivate.h

@@ -111,6 +111,7 @@ typedef struct H5E_t H5E_t;
 /* Retrieve the error code description string and push it onto the error
  * stack.
  */
+#ifndef H5_HAVE_WIN32_API
 #define HSYS_DONE_ERROR(majorcode, minorcode, retcode, str)                                                  \
     {                                                                                                        \
         int myerrno = errno;                                                                                 \
@@ -129,6 +130,35 @@ typedef struct H5E_t H5E_t;
         HGOTO_ERROR(majorcode, minorcode, retcode, "%s, errno = %d, error message = '%s'", str, myerrno,     \
                     HDstrerror(myerrno));                                                                    \
     }
+#else /* H5_HAVE_WIN32_API */
+/* On Windows we also emit the result of GetLastError(). This call returns a DWORD, which is always a
+ * 32-bit unsigned type. Note that on Windows, either errno or GetLastError() (but probably not both) will
+ * be useful depending on whether a C/POSIX or Win32 call failed. The other value will likely be zero,
+ * though I wouldn't count on that.
+ */
+#define HSYS_DONE_ERROR(majorcode, minorcode, retcode, str)                                                  \
+    {                                                                                                        \
+        int   myerrno   = errno;                                                                             \
+        DWORD win_error = GetLastError();                                                                    \
+        /* Other projects may rely on the description format to get the errno and any changes should be      \
+         * considered as an API change                                                                       \
+         */                                                                                                  \
+        HDONE_ERROR(majorcode, minorcode, retcode,                                                           \
+                    "%s, errno = %d, error message = '%s', Win32 GetLastError() = %" PRIu32 "", str,         \
+                    myerrno, HDstrerror(myerrno), win_error);                                                \
+    }
+#define HSYS_GOTO_ERROR(majorcode, minorcode, retcode, str)                                                  \
+    {                                                                                                        \
+        int   myerrno   = errno;                                                                             \
+        DWORD win_error = GetLastError();                                                                    \
+        /* Other projects may rely on the description format to get the errno and any changes should be      \
+         * considered as an API change                                                                       \
+         */                                                                                                  \
+        HGOTO_ERROR(majorcode, minorcode, retcode,                                                           \
+                    "%s, errno = %d, error message = '%s', Win32 GetLastError() = %" PRIu32 "", str,         \
+                    myerrno, HDstrerror(myerrno), win_error);                                                \
+    }
+#endif /* H5_HAVE_WIN32_API */
 
 #ifdef H5_HAVE_PARALLEL
 /*