Windows: _FPCLASS_SNAN’ undeclared on mingw32

[Alexander-Barth]

I am hitting a small issue when compiling NetCDF 4.8.1 on Windows with mingw32. In essence _FPCLASS_SNAN is not defined on mingw32 but isnan is defined like on Linux/Unix. Instead testing _WIN32 the patch checks for _MSC_VER.

• the version of the software with which you are encountering an issue

NetCDF 4.8.1

• environmental information (i.e. Operating System, compiler info, java version, python version, etc.)

OS: Linux x86_64 with cross-compiliation to x86_64-w64-mingw32 (target)
Compiler: x86_64-w64-mingw32-gcc (GCC) 4.8.5

• a description of the issue with the steps needed to reproduce it

I configure and compile NetCDF to the following option:

./configure 
    --build=${MACHTYPE} \                                                                                                                                             
    --host=${target} \                                                                                                                                                
    --enable-shared \                                                                                                                                                 
    --disable-static \                                                                                                                                                
    --disable-dap-remote-tests \    
   --disable-utilities                                                                                                                                  
make LDFLAGS="-lhdf5-0 -lhdf5_hl-0 -lcurl-4 -lz -no-undefined -Wl,--export-all-symbols"                                                                                                                             

The compilation fails with:

[09:16:52] libtool: compile:  cc -DHAVE_CONFIG_H -I. -I.. -I../include -I../include -I../oc2 -D_LARGEFILE_SOURCE -I../libsrc4 -I../libdap4 -I/workspace/destdir/include -std=c99 -fno-strict-aliasing -MT libnczarr_la-zcvt.lo -MD -MP -MF .deps/libnczarr_la-zcvt.Tpo -c zcvt.c  -DDLL_EXPORT -DPIC -o .libs/libnczarr_la-zcvt.o
[09:16:52] libtool: compile:  cc -DHAVE_CONFIG_H -I. -I.. -I../include -I../include -I../oc2 -D_LARGEFILE_SOURCE -I../libsrc4 -I../libdap4 -I/workspace/destdir/include -std=c99 -fno-strict-aliasing -MT libnczarr_la-zxcache.lo -MD -MP -MF .deps/libnczarr_la-zxcache.Tpo -c zxcache.c  -DDLL_EXPORT -DPIC -o .libs/libnczarr_la-zxcache.o
[09:16:52] libtool: compile:  cc -DHAVE_CONFIG_H -I. -I.. -I../include -I../include -I../oc2 -D_LARGEFILE_SOURCE -I../libsrc4 -I../libdap4 -I/workspace/destdir/include -std=c99 -fno-strict-aliasing -MT libnczarr_la-zcreate.lo -MD -MP -MF .deps/libnczarr_la-zcreate.Tpo -c zcreate.c  -DDLL_EXPORT -DPIC -o .libs/libnczarr_la-zcreate.o
[09:16:52] zcvt.c: In function ‘NCZ_stringconvert’:
[09:16:52] zcvt.c:351:3: warning: implicit declaration of function ‘_fpclass’ [-Wimplicit-function-declaration]
[09:16:52]    switch (_fpclass(d)) {
[09:16:52]    ^
[09:16:52] zcvt.c:352:8: error: ‘_FPCLASS_SNAN’ undeclared (first use in this function)
[09:16:52]    case _FPCLASS_SNAN: case _FPCLASS_QNAN:
[09:16:52]         ^
[09:16:52] zcvt.c:352:8: note: each undeclared identifier is reported only once for each function it appears in
[09:16:52] zcvt.c:352:28: error: ‘_FPCLASS_QNAN’ undeclared (first use in this function)
[09:16:52]    case _FPCLASS_SNAN: case _FPCLASS_QNAN:
[09:16:52]                             ^
[09:16:52] zcvt.c:354:8: error: ‘_FPCLASS_NINF’ undeclared (first use in this function)
[09:16:52]    case _FPCLASS_NINF:
[09:16:52]         ^
[09:16:52] zcvt.c:356:8: error: ‘_FPCLASS_PINF’ undeclared (first use in this function)
[09:16:52]    case _FPCLASS_PINF:
[09:16:52]         ^
[09:16:52] make[2]: *** [Makefile:676: libnczarr_la-zcvt.lo] Error 1
[09:16:52] make[2]: *** Waiting for unfinished jobs....


[09:16:52] mv -f .deps/libnczarr_la-zdim.Tpo .deps/libnczarr_la-zdim.Plo
[09:16:52] mv -f .deps/libnczarr_la-zcreate.Tpo .deps/libnczarr_la-zcreate.Plo
[09:16:52] mv -f .deps/libnczarr_la-zchunking.Tpo .deps/libnczarr_la-zchunking.Plo
[09:16:52] mv -f .deps/libnczarr_la-zarr.Tpo .deps/libnczarr_la-zarr.Plo
[09:16:52] mv -f .deps/libnczarr_la-zclose.Tpo .deps/libnczarr_la-zclose.Plo
[09:16:52] mv -f .deps/libnczarr_la-zxcache.Tpo .deps/libnczarr_la-zxcache.Plo
[09:16:52] mv -f .deps/libnczarr_la-zattr.Tpo .deps/libnczarr_la-zattr.Plo
[09:16:52] make[2]: Leaving directory '/workspace/srcdir/netcdf-c-4.8.1/libnczarr'
[09:16:52] make[1]: *** [Makefile:729: all-recursive] Error 1
[09:16:52] make[1]: Leaving directory '/workspace/srcdir/netcdf-c-4.8.1'
[09:16:52] make: *** [Makefile:574: all] Error 2
[09:16:52]  ---> make LDFLAGS="${LDFLAGS_MAKE}" -j${nproc}
[09:16:52]  ---> make LDFLAGS="${LDFLAGS_MAKE}" -j${nproc}
[09:16:52] Previous command exited with 2
[09:16:52] Child Process exited, exit code 2
ERROR: LoadError: Build for NetCDF on x86_64-w64-mingw32 did not complete successfully

This patch solves this issue:

From b7766b6cf56c4792c29d8573c190fb84c8119b59 Mon Sep 17 00:00:00 2001
From: Alexander Barth <[email protected]>
Date: Wed, 2 Mar 2022 15:37:16 +0100
Subject: [PATCH 3/3] _fpclass not defined on mingw

---
 libnczarr/zcvt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libnczarr/zcvt.c b/libnczarr/zcvt.c
index 374eda5b..28f5d223 100644
--- a/libnczarr/zcvt.c
+++ b/libnczarr/zcvt.c
@@ -347,7 +347,7 @@ NCZ_stringconvert(nc_type typeid, size_t len, void* data0, NCjson** jdatap)
 	  	    d = (double)(*((float*)src));
 		else
 	  	    d = *((double*)src);
-#ifdef _WIN32
+#ifdef _MSC_VER
 		switch (_fpclass(d)) {
 		case _FPCLASS_SNAN: case _FPCLASS_QNAN:
 		     special = "Nan"; break;
-- 
2.25.1

I just made a PR for this issue.

Reference:
https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/fpclass-fpclassf?view=msvc-170

[WardF]

Thank you, a PR would be great, although I am curious as to why I am not observing this on my own mingw32 installation. Thanks!

[Alexander-Barth]

Yes, I make a PR here: #2305

[Alexander-Barth]

Thanks for merging the PR.