Hi, On 2022-10-05 16:09:14 -0400, Tom Lane wrote: > Andres Freund <and...@anarazel.de> writes: > > When using precompiled headers we cannot override macros in system headers > > from within .c files, as headers are already processed before the #define in > > the C file is reached. > > > A few files #define FD_SETSIZE 1024 on windows, as the default is only 64. I > > am hesitant to change FD_SETSIZE globally on windows, due to > > src/backend/port/win32/socket.c using it to size on-stack arrays. Instead > > add > > -DFD_SETSIZE=1024 when building the specific targets needing it. > > Color me confused, but how does it work to #define that from the command > line if it can't be overridden from within the program?
If specified on the commandline it's also used when generating the precompiled header - of course that's not possible when it's just #define'd in some .c file. Greetings, Andres Freund
