gdal @3.2.1+postgresql12+proj7 fails due to trying to build grib support even when the +grib variant isn't requested

[cooljeanius (Eric Gallager)]

I'm on macOS Catalian with Xcode 12.3. The error is:

/bin/sh /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/libtool --mode=compile --silent --tag=CC /usr/bin/clang -c -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/port -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/gcore -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/alg -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/ogr -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/ogr/ogrsf_frmts -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/gnm -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/apps -Idegrib/degrib -I../mem -DUSE_PNG -DGNM_ENABLED -mtune=native -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk -I/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/port  -DGDAL_COMPILATION -I/opt/local/include -DHAVE_AVX_AT_COMPILE_TIME -DHAVE_SSSE3_AT_COMPILE_TIME -DHAVE_SSE_AT_COMPILE_TIME -pipe -Os -mtune=native -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk -arch x86_64  -Wall -Wdeclaration-after-statement -Wextra -Winit-self -Wunused-parameter -Wmissing-prototypes -Wmissing-declarations -Wformat -Werror=format-security -Wno-format-nonliteral -Wshorten-64-to-32 -Wshadow -Werror=vla -Wdeclaration-after-statement -Wdate-time -Wnull-dereference -Wcomma -Wfloat-conversion -Wdocumentation -Wno-documentation-deprecated-sync  degrib/g2clib/dec_png.c -o ../o/dec_png.lo
make[2]: Entering directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/frmts/pcraster'
make[2]: Nothing to be done for `install-obj'.
make[2]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/frmts/pcraster'
make[2]: Entering directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/frmts/jpeg'
make[2]: Nothing to be done for `install-obj'.
make[2]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/frmts/jpeg'
In file included from degrib/degrib/grib2api.c:25:
In file included from degrib/g2clib/gridtemplates.h:3:
degrib/g2clib/grib2.h:5:9: warning: 'G2_VERSION' macro redefined [-Wmacro-redefined]
#define G2_VERSION "g2clib-1.6.0"
        ^
/opt/local/include/grib2.h:5:9: note: previous definition is here
#define G2_VERSION "g2clib-1.4.0"
        ^
In file included from degrib/degrib/grib2api.c:25:
In file included from degrib/g2clib/gridtemplates.h:3:
degrib/g2clib/grib2.h:157:13: error: typedef redefinition with different types ('int' vs 'long')
typedef int g2int;
            ^
/opt/local/include/grib2.h:158:14: note: previous definition is here
typedef long g2int;
             ^
In file included from degrib/degrib/grib2api.c:25:
In file included from degrib/g2clib/gridtemplates.h:3:
degrib/g2clib/grib2.h:158:22: error: typedef redefinition with different types ('unsigned int' vs 'unsigned long')
typedef unsigned int g2intu;
                     ^
/opt/local/include/grib2.h:159:23: note: previous definition is here
typedef unsigned long g2intu;
                      ^
In file included from degrib/degrib/grib2api.c:25:
In file included from degrib/g2clib/gridtemplates.h:3:
degrib/g2clib/grib2.h:161:8: error: redefinition of 'gtemplate'
struct gtemplate {
       ^
/opt/local/include/grib2.h:163:8: note: previous definition is here
struct gtemplate {
       ^
In file included from degrib/degrib/grib2api.c:25:
In file included from degrib/g2clib/gridtemplates.h:3:
degrib/g2clib/grib2.h:179:8: error: redefinition of 'gribfield'
struct gribfield {
       ^
/opt/local/include/grib2.h:181:8: note: previous definition is here
struct gribfield {
       ^
degrib/degrib/grib2api.c:845:31: warning: incompatible pointer types passing 'sInt4 [3]' to parameter of type 'g2int *' (aka 'long *') [-Wincompatible-pointer-types]
      ierr = g2_info(c_ipack, listsec0, listsec1, &numfields, &numlocal);
                              ^~~~~~~~
degrib/g2clib/grib2.h:214:38: note: passing argument to parameter here
g2int g2_info(unsigned char *,g2int *,g2int *,g2int *,g2int *);
                                     ^
degrib/degrib/grib2api.c:845:41: warning: incompatible pointer types passing 'sInt4 [13]' to parameter of type 'g2int *' (aka 'long *') [-Wincompatible-pointer-types]
      ierr = g2_info(c_ipack, listsec0, listsec1, &numfields, &numlocal);
                                        ^~~~~~~~
degrib/g2clib/grib2.h:214:46: note: passing argument to parameter here
g2int g2_info(unsigned char *,g2int *,g2int *,g2int *,g2int *);
                                             ^
degrib/degrib/grib2api.c:845:51: warning: incompatible pointer types passing 'sInt4 *' (aka 'int *') to parameter of type 'g2int *' (aka 'long *') [-Wincompatible-pointer-types]
      ierr = g2_info(c_ipack, listsec0, listsec1, &numfields, &numlocal);
                                                  ^~~~~~~~~~
degrib/g2clib/grib2.h:214:54: note: passing argument to parameter here
g2int g2_info(unsigned char *,g2int *,g2int *,g2int *,g2int *);
                                                     ^
degrib/degrib/grib2api.c:845:63: warning: incompatible pointer types passing 'sInt4 *' (aka 'int *') to parameter of type 'g2int *' (aka 'long *') [-Wincompatible-pointer-types]
      ierr = g2_info(c_ipack, listsec0, listsec1, &numfields, &numlocal);
                                                              ^~~~~~~~~
degrib/g2clib/grib2.h:214:62: note: passing argument to parameter here
g2int g2_info(unsigned char *,g2int *,g2int *,g2int *,g2int *);
                                                             ^
degrib/degrib/grib2api.c:1036:19: warning: absolute value function 'abs' given an argument of type 'const g2int' (aka 'const long') but has parameter of type 'int' which may cause truncation of value [-Wabsolute-value]
      curIndex += abs(templatesgrid[gridIndex].mapgrid[i]);
                  ^
degrib/degrib/grib2api.c:1036:19: note: use function 'labs' instead
      curIndex += abs(templatesgrid[gridIndex].mapgrid[i]);
                  ^~~
                  labs
degrib/degrib/grib2api.c:1122:19: warning: absolute value function 'abs' given an argument of type 'const g2int' (aka 'const long') but has parameter of type 'int' which may cause truncation of value [-Wabsolute-value]
      curIndex += abs(templatespds[pdsIndex].mappds[i]);
                  ^
degrib/degrib/grib2api.c:1122:19: note: use function 'labs' instead
      curIndex += abs(templatespds[pdsIndex].mappds[i]);
                  ^~~
                  labs
degrib/degrib/grib2api.c:1141:19: warning: absolute value function 'abs' given an argument of type 'const g2int' (aka 'const long') but has parameter of type 'int' which may cause truncation of value [-Wabsolute-value]
      curIndex += abs(templatesdrs[drsIndex].mapdrs[i]);
                  ^
degrib/degrib/grib2api.c:1141:19: note: use function 'labs' instead
      curIndex += abs(templatesdrs[drsIndex].mapdrs[i]);
                  ^~~
                  labs
degrib/degrib/grib2api.c:1206:65: warning: incompatible pointer types passing 'g2int *' (aka 'long *') to parameter of type 'sInt4 *' (aka 'int *') [-Wincompatible-pointer-types]
         ierr = TransferInt(gfld->fld, gfld->ngrdpts, *ibitmap, gfld->bmap,
                                                                ^~~~~~~~~~
degrib/degrib/grib2api.c:393:31: note: passing argument to parameter 'bmap' here
                       sInt4 *bmap, char f_ignoreScan, sInt4 *scan,
                              ^
degrib/degrib/grib2api.c:1210:65: warning: incompatible pointer types passing 'g2int *' (aka 'long *') to parameter of type 'sInt4 *' (aka 'int *') [-Wincompatible-pointer-types]
         ierr = TransferInt(gfld->fld, gfld->ngrdpts, *ibitmap, gfld->bmap,
                                                                ^~~~~~~~~~
degrib/degrib/grib2api.c:393:31: note: passing argument to parameter 'bmap' here
                       sInt4 *bmap, char f_ignoreScan, sInt4 *scan,
                              ^
degrib/degrib/grib2api.c:1218:31: warning: incompatible pointer types passing 'g2int *' (aka 'long *') to parameter of type 'sInt4 *' (aka 'int *') [-Wincompatible-pointer-types]
                              gfld->bmap, 1, &(dummyScan), 0, 0, *iclean,
                              ^~~~~~~~~~
degrib/degrib/grib2api.c:504:33: note: passing argument to parameter 'bmap' here
                         sInt4 *bmap, char f_ignoreScan, sInt4 *scan,
                                ^
degrib/degrib/grib2api.c:1222:31: warning: incompatible pointer types passing 'g2int *' (aka 'long *') to parameter of type 'sInt4 *' (aka 'int *') [-Wincompatible-pointer-types]
                              gfld->bmap, f_ignoreScan, &(is3[scanIndex]),
                              ^~~~~~~~~~
degrib/degrib/grib2api.c:504:33: note: passing argument to parameter 'bmap' here
                         sInt4 *bmap, char f_ignoreScan, sInt4 *scan,
                                ^
degrib/degrib/grib2api.c:845:14: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'int' [-Wshorten-64-to-32]
      ierr = g2_info(c_ipack, listsec0, listsec1, &numfields, &numlocal);
           ~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
degrib/g2clib/gdal_g2clib_symbol_rename.h:24:17: note: expanded from macro 'g2_info'
#define g2_info gdal_g2_info
                ^
degrib/degrib/grib2api.c:878:11: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'int' [-Wshorten-64-to-32]
   ierr = g2_getfld(c_ipack, *nd5 * sizeof(sInt4), subgNum + 1, unpack, expand, &gfld);
        ~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
degrib/g2clib/gdal_g2clib_symbol_rename.h:22:19: note: expanded from macro 'g2_getfld'
#define g2_getfld gdal_g2_getfld
                  ^
degrib/degrib/grib2api.c:941:19: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is0[6] = gfld->discipline;
          ~ ~~~~~~^~~~~~~~~~
degrib/degrib/grib2api.c:942:19: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is0[7] = gfld->version;
          ~ ~~~~~~^~~~~~~
degrib/degrib/grib2api.c:953:13: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is1[5] = gfld->idsect[0];
          ~ ^~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:954:13: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is1[7] = gfld->idsect[1];
          ~ ^~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:955:13: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is1[9] = gfld->idsect[2];
          ~ ^~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:956:14: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is1[10] = gfld->idsect[3];
           ~ ^~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:957:14: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is1[11] = gfld->idsect[4];
           ~ ^~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:958:14: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is1[12] = gfld->idsect[5]; /* Year */
           ~ ^~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:959:14: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is1[14] = gfld->idsect[6]; /* Month */
           ~ ^~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:960:14: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is1[15] = gfld->idsect[7]; /* Day */
           ~ ^~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:961:14: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is1[16] = gfld->idsect[8]; /* Hour */
           ~ ^~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:962:14: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is1[17] = gfld->idsect[9]; /* Min */
           ~ ^~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:963:14: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is1[18] = gfld->idsect[10]; /* Sec */
           ~ ^~~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:964:14: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is1[19] = gfld->idsect[11];
           ~ ^~~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:965:14: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is1[20] = gfld->idsect[12];
           ~ ^~~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:981:45: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
         mdl_LocalUnpack(gfld->local, gfld->locallen, idat, nidat, rdat,
         ~~~~~~~~~~~~~~~              ~~~~~~^~~~~~~~
degrib/degrib/grib2api.c:997:19: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is3[5] = gfld->griddef;
          ~ ~~~~~~^~~~~~~
degrib/degrib/grib2api.c:998:19: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is3[6] = gfld->ngrdpts;
          ~ ~~~~~~^~~~~~~
degrib/degrib/grib2api.c:1006:20: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is3[10] = gfld->numoct_opt;
           ~ ~~~~~~^~~~~~~~~~
degrib/degrib/grib2api.c:1007:20: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is3[11] = gfld->interp_opt;
           ~ ~~~~~~^~~~~~~~~~
degrib/degrib/grib2api.c:1008:20: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is3[12] = gfld->igdtnum;
           ~ ~~~~~~^~~~~~~
degrib/degrib/grib2api.c:1009:16: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   gridIndex = getgridindex(gfld->igdtnum);
             ~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~
degrib/g2clib/gdal_g2clib_symbol_rename.h:39:22: note: expanded from macro 'getgridindex'
#define getgridindex gdal_getgridindex
                     ^
degrib/degrib/grib2api.c:1035:23: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
      is3[curIndex] = gfld->igdtmpl[i];
                    ~ ^~~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:1036:23: warning: implicit conversion loses integer precision: 'const g2int' (aka 'const long') to 'int' [-Wshorten-64-to-32]
      curIndex += abs(templatesgrid[gridIndex].mapgrid[i]);
                  ~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
degrib/g2clib/gdal_g2clib_symbol_rename.h:65:23: note: expanded from macro 'templatesgrid'
#define templatesgrid gdal_templatesgrid
                      ^
degrib/degrib/grib2api.c:1091:19: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is4[5] = gfld->num_coord;
          ~ ~~~~~~^~~~~~~~~
degrib/degrib/grib2api.c:1092:19: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is4[7] = gfld->ipdtnum;
          ~ ~~~~~~^~~~~~~
degrib/degrib/grib2api.c:1093:15: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   pdsIndex = getpdsindex(gfld->ipdtnum);
            ~ ^~~~~~~~~~~~~~~~~~~~~~~~~~
degrib/g2clib/gdal_g2clib_symbol_rename.h:41:21: note: expanded from macro 'getpdsindex'
#define getpdsindex gdal_getpdsindex
                    ^
degrib/degrib/grib2api.c:1113:23: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
      is4[curIndex] = gfld->ipdtmpl[i];
                    ~ ^~~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:1122:23: warning: implicit conversion loses integer precision: 'const g2int' (aka 'const long') to 'int' [-Wshorten-64-to-32]
      curIndex += abs(templatespds[pdsIndex].mappds[i]);
                  ~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
degrib/g2clib/gdal_g2clib_symbol_rename.h:66:22: note: expanded from macro 'templatespds'
#define templatespds gdal_templatespds
                     ^
degrib/degrib/grib2api.c:1127:19: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is5[5] = gfld->ndpts;
          ~ ~~~~~~^~~~~
degrib/degrib/grib2api.c:1128:19: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is5[9] = gfld->idrtnum;
          ~ ~~~~~~^~~~~~~
degrib/degrib/grib2api.c:1129:15: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   drsIndex = getdrsindex(gfld->idrtnum);
            ~ ^~~~~~~~~~~~~~~~~~~~~~~~~~
degrib/g2clib/gdal_g2clib_symbol_rename.h:37:21: note: expanded from macro 'getdrsindex'
#define getdrsindex gdal_getdrsindex
                    ^
degrib/degrib/grib2api.c:1140:23: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
      is5[curIndex] = gfld->idrtmpl[i];
                    ~ ^~~~~~~~~~~~~~~~
degrib/degrib/grib2api.c:1141:23: warning: implicit conversion loses integer precision: 'const g2int' (aka 'const long') to 'int' [-Wshorten-64-to-32]
      curIndex += abs(templatesdrs[drsIndex].mapdrs[i]);
                  ~~~ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
degrib/g2clib/gdal_g2clib_symbol_rename.h:64:22: note: expanded from macro 'templatesdrs'
#define templatesdrs gdal_templatesdrs
                     ^
degrib/degrib/grib2api.c:1161:19: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
   is6[5] = gfld->ibmap;
          ~ ~~~~~~^~~~~
degrib/degrib/grib2api.c:1206:46: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
         ierr = TransferInt(gfld->fld, gfld->ngrdpts, *ibitmap, gfld->bmap,
                ~~~~~~~~~~~            ~~~~~~^~~~~~~
degrib/degrib/grib2api.c:1210:46: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
         ierr = TransferInt(gfld->fld, gfld->ngrdpts, *ibitmap, gfld->bmap,
                ~~~~~~~~~~~            ~~~~~~^~~~~~~
degrib/degrib/grib2api.c:1217:48: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
         ierr = TransferFloat(gfld->fld, gfld->ngrdpts, *ibitmap,
                ~~~~~~~~~~~~~            ~~~~~~^~~~~~~
degrib/degrib/grib2api.c:1221:48: warning: implicit conversion loses integer precision: 'g2int' (aka 'long') to 'sInt4' (aka 'int') [-Wshorten-64-to-32]
         ierr = TransferFloat(gfld->fld, gfld->ngrdpts, *ibitmap,
                ~~~~~~~~~~~~~            ~~~~~~^~~~~~~
53 warnings and 4 errors generated.
make[2]: *** [../o/grib2api.lo] Error 1
make[2]: *** Waiting for unfinished jobs....
make[2]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/frmts/grib'
make[1]: *** [grib-install-obj] Error 2
make[1]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1/frmts'
make: *** [frmts-target] Error 2
make: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1'
Command failed:  cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/work/gdal-3.2.1" && /usr/bin/make -j16 -w 
Exit code: 2
Error: Failed to build gdal: command execution failed
DEBUG: Error code: CHILDSTATUS 77236 2
DEBUG: Backtrace: command execution failed
    while executing
"system {*}$notty {*}$nice $fullcmdstring"
    invoked from within
"command_exec build"
    (procedure "portbuild::build_main" line 8)
    invoked from within
"$procedure $targetname"
Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_gis_gdal/gdal/main.log for details.
DEBUG: Registry error: port:wgrib2 not registered as installed & active.
Error: Follow https://guide.macports.org/#project.tickets to report a bug.

Even though the error message says wgrib2 isn't registered as installed & active, that is not true, as that is where the offending header comes from:

$ port provides /opt/local/include/grib2.h 
/opt/local/include/grib2.h is provided by: wgrib2

Deactivating wgrib2 allows the build to succeed. Either a build conflict should be declared using the conflicts_build PortGroup, or gdal's build process should be patched to explicitly ignore wgrib2 when the +grib variant isn't selected.