RFR: 8214976: Warn about uses of functions replaced for portability

[Harold Seigel]

On Tue, 4 Jan 2022 19:23:24 GMT, Harold Seigel <hseigel at openjdk.org> wrote:

> Please review this change for JDK-8214976.  This change adds attribute warnings to header file compilerWarnings.hpp so that compilation warnings get issued when certain system functions are called directly, instead of hotspot's os:: versions of the functions.  Many additional files were changed because of compilation warnings resulting from the compilerWarnings.hpp changes.
> 
> A sample warning is:
> 
> .../open/test/hotspot/gtest/logging/test_log.cpp:63:19: error: call to 'fopen' declared with attribute warning: use os::fopen [-Werror=attribute-warning]
>    63 |   FILE* fp = fopen(TestLogFileName, "r");
>       |              ~~~~~^~~~~~~~~~~~~~~~~~~~~~
> 
> 
> Note that changing src/hotspot/os/linux/gc/z/zMountPoint_linux.cpp to call os:: functions requires adding "#include "runtime/os.hpp" and caused test gc/z/TestAllocateHeapAt.java to fail.  So, for now, I just added PRAGMA_PERMIT_FORBIDDEN_C_FUNCTION to zMountPoint_linux.cpp.  There's a similar issue with gtest/logging/test_logDecorators.cpp.
> 
> Attribute warnings for additional functions, such as malloc(), were not included in this change because they require lots of source code changes.
> 
> This change was tested by running mach5 tiers 1-2 on Linux, Mac OS, and Windows, Mach5 tiers 3-5 on Linux x64.  Also, builds were done on Linux-zero, Linux-s390, and Linux-ppc.
> 
> Thanks, Harold

Hi Kim,

I don't think that FORBIDDEN_C_FUNCTION should be enforced for files os_aix.cpp, os_bsd.cpp, os_posix.cpp, and os_windows.cpp.  These are platform specific files that intentionally call multiple native functions.  For example, os_linux.cpp calls close_dir() fopen(), close(), readdir(), write(), lseek(), etc.

Since PRAGMA_PERMIT_FORBIDDEN_C_FUNCTION ignores its argument and disables the warning for all native calls, I think it's reasonable to just specify  PRAGMA_PERMIT_FORBIDDEN_C_FUNCTION once at the beginning of the above files and not clutter them with many PRAGMA_DIAG_PUSH/POP's.

Thanks, Harold

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PR: https://git.openjdk.java.net/jdk/pull/6961