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

[Kim Barrett]

On Thu, 27 Jan 2022 19:18:10 GMT, Harold Seigel <hseigel at openjdk.org> wrote:

> Please review this new attempt to resolve JDK-8214976.  This fix adds Pragmas to generate compilation errors, when using gcc, if calling a native system function instead of the os:: version of the function.  The fix includes changes to calls in non-shared code because it is cleaner than adding PRAGMAs and, for some cases, the os:: version of a function has added value, such as asserts and RESTARTABLE.  This fix slightly changes the signature of os::abort() so it wouldn't conflict with native abort() functions.  Changes to Windows code is left for a future RFE.
> 
> This fix was tested with Mach5 tiers 1-2 on Linux, Mac OS, and Windows, Mach5 tiers 3-5 on Linux x64, and Mach5 builds of Zero, PPC, and s390.
> 
> Thanks, Harold

Changes requested by kbarrett (Reviewer).

src/hotspot/share/utilities/compilerWarnings_gcc.hpp line 109:

> 107: FORBID_C_FUNCTION(ssize_t  write(int, const void*, size_t ),          "use os::write");
> 108: 
> 109: FORBID_C_FUNCTION(char*    strtok(char*, const char*),                "use strtok_r");

Some of these functions are portable and ought to be forbidden in a platform agnostic location, so the restriction also applies if/when we have real support on other platforms.  I think almost none are gcc (or clang) specific, but are instead probably posix and not windows, so maybe should go in a different place as well.  Basically I think the structure / placement considerations need some more work.

src/hotspot/share/utilities/compilerWarnings_gcc.hpp line 114:

> 112: 
> 113: #define FORBID_C_FUNCTION(signature, alternative)
> 114: #define PRAGMA_PERMIT_FORBIDDEN_C_FUNCTION(name)

These aren't needed.  The default empty definitions in compilerWarnings.hpp cover this case.

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PR: https://git.openjdk.java.net/jdk/pull/7248