Several builds under examples/third_party fail at HEAD

[bcsgh]

The stuff under examples/third_party looks like it could be a highly valuable resource, but I'm not actually sure any of it works. Which is annoying.

Reproduction:

T=rules_foreign_cc
git clone https://github.com/bazelbuild/rules_foreign_cc.git $T
cd $T/examples/third_party

bazel build -k :all
# More complete:
bazel build -k ...
# Most (likely too)  complete:
bazel query 'kind("http_archive|git_repository",//external:*)' |
    sed "/:.*[/]/d;s/.*:/@/;s~$~//:all~" |
    bazel build -k $(cat)

ERRORS

@rules_perl// (needed by @openssl//)

ERROR: [...]/external/rules_perl/BUILD:74:23: While resolving toolchains for target @rules_perl//:current_toolchain: No matching toolchains found for types @rules_perl//:toolchain_type.
To debug, rerun with --toolchain_resolution_debug='@rules_perl//:toolchain_type'

See fix(?) in PR #1137

@mesa//

Error in download_and_extract: java.io.IOException: Error downloading [https://archive.mesa3d.org//mesa-22.1.4.tar.xz] to [...]/external/mesa/temp12780688070917179032/mesa-22.1.4.tar.xz: No route to host (Host unreachable)

@libpng//

ERROR: [...]/external/libpng/BUILD.bazel:13:6: Foreign Cc - CMake: Building libpng failed:
[...]
external/libpng/contrib/libtests/pngstest.c:3216:24: error: '%d' directive writing between 1 and 11 bytes into a region of size between 10 and 32 [-Werror=format-overflow=]
 3216 |       sprintf(name, "%s%d.png", tmpf, ++counter);
      |                        ^~
[...]

@gperftools//

ERROR: [...]/external/gperftools/BUILD.bazel:11:15: Foreign Cc - Configure: Building gperftools_build failed:
[...]
external/gperftools/src/tcmalloc.cc:2098:36: error: 'void tc_delete_aligned_nothrow(void*, std::align_val_t, const std::nothrow_t&)' alias between functions of incompatible types 'void(void*, std::align_val_t, const std::nothrow_t&)' and 'void(void*)' [-Werror=attribute-alias=]
 2098 | extern "C" PERFTOOLS_DLL_DECL void tc_delete_aligned_nothrow(void* p, std::align_val_t, const std::nothrow_t&) PERFTOOLS_NOTHROW
      |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~
[...]

ERROR: [...]/external/iconv/BUILD.bazel:8:15: Foreign Cc - Configure: Building iconv failed:

@iconv//

WARNING: The target pattern '@iconv//:all' is ambiguous: ':all' is both a wildcard, and the name of an existing filegroup rule; using the latter interpretation
WARNING: The target pattern '@iconv_macos//:all' is ambiguous: ':all' is both a wildcard, and the name of an existing filegroup rule; using the latter interpretation

ERROR: [...]/external/iconv/BUILD.bazel:8:15: Foreign Cc - Configure: Building iconv failed:
[...]
In file included from ./iconv.c:73,
                 from ./iconv_no_i18n.c:2:
./iconv.c: In function 'main':
../srclib/gettext.h:86:34: error: statement with no effect [-Werror=unused-value]
   86 | # define textdomain(Domainname) ((const char *) (Domainname))
      |                                 ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
./iconv.c:863:3: note: in expansion of macro 'textdomain'
  863 |   textdomain("libiconv");
      |   ^~~~~~~~~~
[...]

(And a few more)

[jsharpe]

Note that in CI we don't actually run these directly from the examples/third_party workspace but import them from the examples workspace so you may have more luck building these targets from the examples directory.

Also what version of Bazel are you using and what platform?

[bcsgh]

IMHO in an official repo, any directory of examples that looks like a workspace should be supported. The optics of "they can't even keep the official examples working!" is just bad for marketing. Either that or it should be so clearly broken that nobody would ever be forgiven for expecting it to work. (E.g. make the WORKSPACE file nothing but a comment pointing at where it should be used from.)

FWIW: if it were up to me, there would be a second set of directories with a workspace for each of the ones under third_party with full CI making sure that each works individually and that none of them just work because another is randomly including the right thing.