The source we are currently using is from 2015. The upstream repo has
received a small number of bug fixes and improvements since then.
Including one that fixes an issue for Windows users:
https://github.com/miniupnp/libnatpmp/pull/13.
The source we are currently using is the most recent "official" release,
however I don't think it's worth waiting for a new one. The maintainer
was prompted to do so in Oct 2020, then again in Jan of this year, and
no release has eventuated. Given libnatpmp is a new inclusion into our
repository, I think we should be using this newer source.
This also cleans up a few warnings we currently see in depends builds:
```bash
Extracting libnatpmp...
/home/ubuntu/bitcoin/depends/sources/libnatpmp-20150609.tar.gz: OK
Preprocessing libnatpmp...
Configuring libnatpmp...
Building libnatpmp...
make[1]: Entering directory '/home/ubuntu/bitcoin/depends/work/build/x86_64-w64-mingw32/libnatpmp/20150609-13efa1beb87'
x86_64-w64-mingw32-gcc -Os -fPIC -Wall -DENABLE_STRNATPMPERR -c -o natpmp.o natpmp.c
x86_64-w64-mingw32-gcc -Os -fPIC -Wall -DENABLE_STRNATPMPERR -c -o getgateway.o getgateway.c
natpmp.c:42: warning: "EWOULDBLOCK" redefined
42 | #define EWOULDBLOCK WSAEWOULDBLOCK
|
In file included from natpmp.c:38:
/usr/share/mingw-w64/include/errno.h:166: note: this is the location of the previous definition
166 | #define EWOULDBLOCK 140
|
natpmp.c:43: warning: "ECONNREFUSED" redefined
43 | #define ECONNREFUSED WSAECONNREFUSED
|
In file included from natpmp.c:38:
/usr/share/mingw-w64/include/errno.h:110: note: this is the location of the previous definition
110 | #define ECONNREFUSED 107
|
natpmp.c:271:5: warning: ‘readnatpmpresponseorretry’ redeclared without dllimport attribute: previous dllimport ignored [-Wattributes]
271 | int readnatpmpresponseorretry(natpmp_t * p, natpmpresp_t * response)
| ^~~~~~~~~~~~~~~~~~~~~~~~~
ar crs libnatpmp.a natpmp.o getgateway.o
make[1]: Leaving directory '/home/ubuntu/bitcoin/depends/work/build/x86_64-w64-mingw32/libnatpmp/20150609-13efa1beb87'
Staging libnatpmp...
Postprocessing libnatpmp...
Caching libnatpmp...
```
Currently, our cross-compile of libnatpmp for macOS doesn't work at all.
The wrong archiver is used, which produces an archive the linker doesn't like.
This becomes clear when configuring:
```bash
configure:25722: checking for initnatpmp in -lnatpmp
configure:25747: env -u C_INCLUDE_PATH -u CPLUS_INCLUDE_PATH -u OBJC_INCLUDE_PATH -u OBJCPLUS_INCLUDE_PATH -u CPATH -u LIBRARY_PATH /home/ubuntu/bitcoin/depends/x86_64-apple-darwin18/native/bin/clang++ --target=x86_64-apple-darwin18 <trim> -Wl,-headerpad_max_install_names -Wl,-dead_strip -Wl,-dead_strip_dylibs conftest.cpp -lnatpmp >&5
ld: archive has no table of contents for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
```
Fix this by using the right `ar` (we do the same for upnp).
While we're at it, we fixe the build so that we are using our c/ppflags.
This means building with `-O2` rather than `-Os`.
Note that this fixes an issue that is also fixed by #21209.
However, given there are reservations about updating to use a newer libnatpmp source, we should just fix this for now.
