RFR: 8214976: Warn about uses of functions replaced for portability [v2]

[David Holmes]

On Tue, 1 Feb 2022 14:08:40 GMT, Harold Seigel <hseigel at openjdk.org> wrote:

>> src/hotspot/share/utilities/compilerWarnings_gcc.hpp line 97:
>> 
>>> 95: FORBID_C_FUNCTION(FILE*    fopen(const char*, const char*),           "use os::fopen");
>>> 96: FORBID_C_FUNCTION(int      fsync(int),                                "use os::fsync");
>>> 97: FORBID_C_FUNCTION(int      ftruncate(int, off_t),                     "use os::ftruncate");
>> 
>> Shouldn't this be ftruncate for BSD and ftruncate64 for other Posix (not sure what Windows has)?
>
> Platform agnostic code would call ftruncate(), not ftruncate64().  So I think this is correct as is.

You need to enable the warning for the function that we would use, which we are not supposed to use and that would be `ftruncate64` on Linux.

>> src/hotspot/share/utilities/compilerWarnings_gcc.hpp line 99:
>> 
>>> 97: FORBID_C_FUNCTION(int      ftruncate(int, off_t),                     "use os::ftruncate");
>>> 98: FORBID_C_FUNCTION(void     funlockfile(FILE *),                       "use os::funlockfile");
>>> 99: FORBID_C_FUNCTION(off_t    lseek(int, off_t, int),                    "use os::lseek");
>> 
>> Similarly there should be a lseek64 definition too.
>
> Like ftruncate(), platform agnostic code would call lseek(), not lseek64().  So I think this is correct as is.

I disagree - you are not enabling the warnings for all the functions that would be used.

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