Add farmhash

[ericriff]

Specify library name and version: farmhash

One more step towards tensorflow-lite #7165

---

• I've read the guidelines for contributing.
• I've followed the PEP8 style guides for Python code in the recipes.
• I've used the latest Conan client version.
• I've tried at least one configuration locally with the
  conan-center hook activated.

[ericriff]

Help from a Windows developer is welcome here.

[conan-center-bot]

All green in build 7 (934384ceb2020fc4676ccd82348bf6689e15e7b8):

• farmhash/cci.20190513@:
  All packages built successfully! (All logs)

[ericriff]

I no longer need this package and I don't know what is going on with Windows (I don't have a windows PC to test this). Is it OK if we merge this recipe without windows support?
I can't spend much time on it and as I said I no longer need it.

[SSE4]

I no longer need this package and I don't know what is going on with Windows (I don't have a windows PC to test this). Is it OK if we merge this recipe without windows support?
I can't spend much time on it and as I said I no longer need it.

in general, this is perfectly find, if very first iteration doesn't support all platforms.
someone who actually needs Windows may add support in a follow up PRs.

for the farmhash in particular, I've tried to build it for Windows/VS, but it doesn't build out of the box.
for whose would like to continue the effort, the initial patch is:

diff --git a/recipes/farmhash/all/conanfile.py b/recipes/farmhash/all/conanfile.py
index 859923b3b..a65885dbc 100644
--- a/recipes/farmhash/all/conanfile.py
+++ b/recipes/farmhash/all/conanfile.py
@@ -1,4 +1,5 @@
 from conans import ConanFile, tools, AutoToolsBuildEnvironment
+import contextlib
 import os
 
 required_conan_version = ">=1.33.0"
@@ -44,11 +45,31 @@ class farmhashConan(ConanFile):
     def build_requirements(self):
         if self._settings_build.os == "Windows" and not tools.get_env("CONAN_BASH_PATH"):
             self.build_requires("msys2/cci.latest")
+        if self.settings.compiler == "Visual Studio":
+            self.build_requires("automake/1.16.3")
 
     def source(self):
         tools.get(**self.conan_data["sources"][self.version], strip_root=True,
                   destination=self._source_subfolder)
 
+    @property
+    def _user_info_build(self):
+        return getattr(self, "user_info_build", self.deps_user_info)
+
+    @contextlib.contextmanager
+    def _build_context(self):
+        if self.settings.compiler == "Visual Studio":
+            with tools.vcvars(self):
+                env = {
+                    "CC": "{} cl -nologo".format(tools.unix_path(self._user_info_build["automake"].compile)),
+                    "CXX": "{} cl -nologo".format(tools.unix_path(self._user_info_build["automake"].compile)),
+                    "CPP": "{} cl -E".format(tools.unix_path(self._user_info_build["automake"].compile)),
+                }
+                with tools.environment_append(env):
+                    yield
+        else:
+            yield
+
     def _configure_autotools(self):
         if self._autotools:
             return self._autotools
@@ -58,18 +79,21 @@ class farmhashConan(ConanFile):
             conf_args.extend(["--enable-shared", "--disable-static"])
         else:
             conf_args.extend(["--disable-shared", "--enable-static"])
-        if self.options.no_builtin_expect:
+        if self.options.no_builtin_expect or self.settings.compiler == "Visual Studio":
             self._autotools.defines.append("FARMHASH_NO_BUILTIN_EXPECT")
+            self._autotools.defines.append("__builtin_unreachable=abort")
         self._autotools.configure(configure_dir=self._source_subfolder, args=conf_args)
         return self._autotools
 
     def build(self):
-        autotools = self._configure_autotools()
-        autotools.make()
+        with self._build_context():
+            autotools = self._configure_autotools()
+            autotools.make()
 
     def package(self):
-        autotools = self._configure_autotools()
-        autotools.install()
+        with self._build_context():
+            autotools = self._configure_autotools()
+            autotools.install()
         self.copy("COPYING", src=self._source_subfolder, dst="licenses")
         tools.remove_files_by_mask(os.path.join(self.package_folder, "lib"), "*.la")
         tools.rmdir(os.path.join(self.package_folder, "share"))

it will at least start to build for VS. but there will be many compiler errors of the same kind:

C:\users\sse4\.conan\data\farmhash\cci.20190513\_\_\build\3fb49604f9c2f729b85ba3115852006824e72cab\source_subfolder\src\farmhash.cc(2012): error C2872: 'data': ambiguous symbol
C:\users\sse4\.conan\data\farmhash\cci.20190513\_\_\build\3fb49604f9c2f729b85ba3115852006824e72cab\source_subfolder\src\farmhash.cc(1996): note: could be 'char data[1048576]'
C:\users\sse4\.conan\data\farmhash\cci.20190513\_\_\build\3fb49604f9c2f729b85ba3115852006824e72cab\source_subfolder\src\farmhash.cc(2012): note: or       'data'

it seems like upstream just doesn't support Visual Studio out of the box, and it may require some patching.

[uilianries]

Yes, any future improvement will be welcome too. Thanks for providing it.

[prince-chrismc]

There's a typo but not worth fixing... next PR hopefully

[prince-chrismc]

Suggested change

	class farmhashConan(ConanFile):
	class FarmhashConan(ConanFile):