$ rm -fr build ; CFLAGS=" -std=c89" cmake  -S . -B build  -D CMAKE_BUILD_TYPE=Release -D CMAKE_C_COMPILER=clang -D ZLIB_BUILD_EXAMPLES=off 
-- The C compiler identification is Clang 16.0.6
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/clang - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Looking for sys/types.h
-- Looking for sys/types.h - found
-- Looking for stdint.h
-- Looking for stdint.h - found
-- Looking for stddef.h
-- Looking for stddef.h - found
-- Check size of off64_t
-- Check size of off64_t - done
-- Looking for fseeko
-- Looking for fseeko - found
-- Looking for unistd.h
-- Looking for unistd.h - found
-- Looking for stdarg.h
-- Looking for stdarg.h - found
-- Configuring done (2.1s)
-- Generating done (0.0s)
-- Build files have been written to: /home/paul/git/zlib/build

$ cmake --build build
[  3%] Building C object CMakeFiles/zlib.dir/adler32.c.o
[  6%] Building C object CMakeFiles/zlib.dir/compress.c.o
[  9%] Building C object CMakeFiles/zlib.dir/crc32.c.o
[ 12%] Building C object CMakeFiles/zlib.dir/deflate.c.o
[ 15%] Building C object CMakeFiles/zlib.dir/gzclose.c.o
[ 18%] Building C object CMakeFiles/zlib.dir/gzlib.c.o
/home/paul/git/zlib/gzlib.c:204:15: warning: implicitly declaring library function 'snprintf' with type 'int (char *, unsigned long, const char *, ...)' [-Wimplicit-function-declaration]
        (void)snprintf(state->path, len + 1, "%s", (const char *)path);
              ^
/home/paul/git/zlib/gzlib.c:204:15: note: include the header <stdio.h> or explicitly provide a declaration for 'snprintf'
1 warning generated.
[ 21%] Building C object CMakeFiles/zlib.dir/gzread.c.o
[ 25%] Building C object CMakeFiles/zlib.dir/gzwrite.c.o
/home/paul/git/zlib/gzwrite.c:407:11: warning: implicitly declaring library function 'vsnprintf' with type 'int (char *, unsigned long, const char *, struct __va_list_tag *)' [-Wimplicit-function-declaration]
    len = vsnprintf(next, state->size, format, va);
          ^
/home/paul/git/zlib/gzwrite.c:407:11: note: include the header <stdio.h> or explicitly provide a declaration for 'vsnprintf'
1 warning generated.
[ 28%] Building C object CMakeFiles/zlib.dir/inflate.c.o
[ 31%] Building C object CMakeFiles/zlib.dir/infback.c.o
[ 34%] Building C object CMakeFiles/zlib.dir/inftrees.c.o
[ 37%] Building C object CMakeFiles/zlib.dir/inffast.c.o
[ 40%] Building C object CMakeFiles/zlib.dir/trees.c.o
[ 43%] Building C object CMakeFiles/zlib.dir/uncompr.c.o
[ 46%] Building C object CMakeFiles/zlib.dir/zutil.c.o
[ 50%] Linking C shared library libz.so
[ 50%] Built target zlib
[ 53%] Building C object CMakeFiles/zlibstatic.dir/adler32.c.o
[ 56%] Building C object CMakeFiles/zlibstatic.dir/compress.c.o
[ 59%] Building C object CMakeFiles/zlibstatic.dir/crc32.c.o
[ 62%] Building C object CMakeFiles/zlibstatic.dir/deflate.c.o
[ 65%] Building C object CMakeFiles/zlibstatic.dir/gzclose.c.o
[ 68%] Building C object CMakeFiles/zlibstatic.dir/gzlib.c.o
/home/paul/git/zlib/gzlib.c:204:15: warning: implicitly declaring library function 'snprintf' with type 'int (char *, unsigned long, const char *, ...)' [-Wimplicit-function-declaration]
        (void)snprintf(state->path, len + 1, "%s", (const char *)path);
              ^
/home/paul/git/zlib/gzlib.c:204:15: note: include the header <stdio.h> or explicitly provide a declaration for 'snprintf'
1 warning generated.
[ 71%] Building C object CMakeFiles/zlibstatic.dir/gzread.c.o
[ 75%] Building C object CMakeFiles/zlibstatic.dir/gzwrite.c.o
/home/paul/git/zlib/gzwrite.c:407:11: warning: implicitly declaring library function 'vsnprintf' with type 'int (char *, unsigned long, const char *, struct __va_list_tag *)' [-Wimplicit-function-declaration]
    len = vsnprintf(next, state->size, format, va);
          ^
/home/paul/git/zlib/gzwrite.c:407:11: note: include the header <stdio.h> or explicitly provide a declaration for 'vsnprintf'
1 warning generated.
[ 78%] Building C object CMakeFiles/zlibstatic.dir/inflate.c.o
[ 81%] Building C object CMakeFiles/zlibstatic.dir/infback.c.o
[ 84%] Building C object CMakeFiles/zlibstatic.dir/inftrees.c.o
[ 87%] Building C object CMakeFiles/zlibstatic.dir/inffast.c.o
[ 90%] Building C object CMakeFiles/zlibstatic.dir/trees.c.o
[ 93%] Building C object CMakeFiles/zlibstatic.dir/uncompr.c.o
[ 96%] Building C object CMakeFiles/zlibstatic.dir/zutil.c.o
[100%] Linking C static library libz.a
[100%] Built target zlibstatic