go plugin: cross-compilation support

integration_tests/plugins/test_go_plugin.py

@@ -18,6 +18,7 @@
 import subprocess
 
 import integration_tests
+import snapcraft
 
 
 class GoPluginTestCase(integration_tests.TestCase):
@@ -33,3 +34,10 @@ def test_stage_go_plugin(self):
 
     def test_building_multiple_main_packages(self):
         self.run_snapcraft('stage', 'go-with-multiple-main-packages')
+
+    def test_cross_compiling(self):
+        if snapcraft.ProjectOptions().deb_arch != 'amd64':
+            self.skipTest('The test only handles amd64 to armhf')
+
+        arch = 'armhf'
+        self.run_snapcraft('stage', 'go-cgo', '--target={}'.format(arch))

integration_tests/snaps/go-cgo/main.go

@@ -0,0 +1,44 @@
+// -*- Mode: Go; indent-tabs-mode: t -*-
+
+/*
+ * Copyright (C) 2017 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package main
+
+/*
+#cgo pkg-config: glib-2.0
+#cgo LDFLAGS: -lm
+#include <math.h>
+#include <glib.h>
+
+*/
+import "C"
+
+import (
+	"fmt"
+	"os/user"
+)
+
+func main() {
+	u, err := user.Current()
+	if err != nil {
+		panic(err)
+	}
+	fmt.Println("user according to go:", u.Username)
+	fmt.Println("user according to glib:", C.GoString((*C.char)(C.g_get_user_name())))
+	fmt.Println("more or less 1:", C.sin(3.14/2))
+}

integration_tests/snaps/go-cgo/snapcraft.yaml

@@ -0,0 +1,14 @@
+name: go-cgo
+version: 0.1
+summary: A go project using libraries written in C.
+description: |
+  This is a basic go snap that uses cgo to access C APIs.
+  The name of the binary will be that of the directory containing it,
+  just like it is seen when using `go build` or `go install`.
+confinement: strict
+
+parts:
+  go-cgo:
+    plugin: go
+    source: .
+    build-packages: [libglib2.0-dev]

integration_tests/test_multiarch_stage_packages.py

@@ -31,6 +31,4 @@ def test_bad_multiarch_stage_packages(self):
         self.assertThat(
             exception.output, Contains(
                 "Error downloading stage packages for part 'my-part': The "
-                "package 'hello:fake-arch' was not found.\n"
-                'You may need to add support for this architecture with '
-                "'dpkg --add-architecture fake-arch'"))
+                "package 'hello:fake-arch' was not found.\n"))

integration_tests/test_snap.py

@@ -124,7 +124,7 @@ def test_error_with_unexistent_build_package(self):
             subprocess.CalledProcessError, self.run_snapcraft, 'snap')
         expected = (
             "Could not find a required package in 'build-packages': "
-            '"The cache has no package named \'inexistent-package\'"\n')
+            'inexistent-package\n')
         self.assertThat(exception.output, EndsWith(expected))
 
     def test_snap_with_exposed_files(self):

snapcraft/_options.py

@@ -33,7 +33,8 @@
         'deb': 'armhf',
         'uts_machine': 'arm',
         'cross-compiler-prefix': 'arm-linux-gnueabihf-',
-        'cross-build-packages': ['gcc-arm-linux-gnueabihf'],
+        'cross-build-packages': ['gcc-arm-linux-gnueabihf',
+                                 'libc6-dev-armhf-cross'],
         'triplet': 'arm-linux-gnueabihf',
         'core-dynamic-linker': 'lib/ld-linux-armhf.so.3',
     },
@@ -42,7 +43,8 @@
         'deb': 'arm64',
         'uts_machine': 'aarch64',
         'cross-compiler-prefix': 'aarch64-linux-gnu-',
-        'cross-build-packages': ['gcc-aarch64-linux-gnu'],
+        'cross-build-packages': ['gcc-aarch64-linux-gnu',
+                                 'libc6-dev-arm64-cross'],
         'triplet': 'aarch64-linux-gnu',
         'core-dynamic-linker': 'lib/ld-linux-aarch64.so.1',
     },
@@ -57,7 +59,8 @@
         'deb': 'ppc64el',
         'uts_machine': 'ppc64el',
         'cross-compiler-prefix': 'powerpc64le-linux-gnu-',
-        'cross-build-packages': ['gcc-powerpc64le-linux-gnu'],
+        'cross-build-packages': ['gcc-powerpc64le-linux-gnu',
+                                 'libc6-dev-ppc64el-cross'],
         'triplet': 'powerpc64le-linux-gnu',
         'core-dynamic-linker': '/lib64/ld64.so.2',
     },
@@ -66,7 +69,8 @@
         'deb': 'powerpc',
         'uts_machine': 'powerpc',
         'cross-compiler-prefix': 'powerpc-linux-gnu-',
-        'cross-build-packages': ['gcc-powerpc-linux-gnu'],
+        'cross-build-packages': ['gcc-powerpc-linux-gnu',
+                                 'libc6-dev-powerpc-cross'],
         'triplet': 'powerpc-linux-gnu',
     },
     'x86_64': {
@@ -81,7 +85,8 @@
         'deb': 's390x',
         'uts_machine': 's390x',
         'cross-compiler-prefix': 's390x-linux-gnu-',
-        'cross-build-packages': ['gcc-s390x-linux-gnu'],
+        'cross-build-packages': ['gcc-s390x-linux-gnu',
+                                 'libc6-dev-s390x-cross'],
         'triplet': 's390x-linux-gnu',
         'core-dynamic-linker': '/lib/ld64.so.1',
     }
@@ -145,8 +150,8 @@ def cross_compiler_prefix(self):
     def additional_build_packages(self):
         packages = []
         if self.is_cross_compiling:
-            packages.extend(self.__machine_info.get(
-                'cross-build-packages', []))
+            for package in self.__machine_info.get('cross-build-packages', []):
+                packages.append('{}:native'.format(package))
         return packages
 
     @property

snapcraft/internal/lifecycle.py

@@ -108,7 +108,8 @@ def execute(step, project_options, part_names=None):
     :returns: A dict with the snap name, version, type and architectures.
     """
     config = snapcraft.internal.load_config(project_options)
-    repo.Repo.install_build_packages(config.build_tools)
+    repo.Repo.install_build_packages(config.build_tools,
+                                     project_options.deb_arch)
 
     if (os.environ.get('SNAPCRAFT_SETUP_CORE') and
             config.data['confinement'] == 'classic'):

snapcraft/internal/project_loader.py

@@ -356,6 +356,10 @@ def _build_env(root, snap_name, confinement, arch_triplet,
         env.append(formatting_utils.format_path_variable(
             'PKG_CONFIG_PATH', paths, prepend='', separator=':'))
 
+    paths = common.get_pkg_config_paths('/', arch_triplet)
+    env.append(formatting_utils.format_path_variable(
+        'PKG_CONFIG_PATH', paths, prepend='', separator=':'))
+
     return env
 
 

snapcraft/internal/repo/__init__.py

@@ -34,11 +34,19 @@ def check_for_command(command):
 
 
 def get_pkg_name_parts(pkg_name):
-    """Break package name into base parts"""
+    """Break package name:arch=version into base parts"""
 
     name = pkg_name
     version = None
     with contextlib.suppress(ValueError):
         name, version = pkg_name.split('=')
 
-    return name, version
+    arch = ''
+    if ':' in name:
+        name, arch = name.rsplit(':', 1)
+        if arch == 'any':
+            arch = ''
+        else:
+            arch = ':' + arch
+
+    return name, arch, version

snapcraft/internal/repo/_base.py

@@ -90,11 +90,12 @@ def get_packages_for_source_type(cls, source_type):
         raise NotImplementedError()
 
     @classmethod
-    def install_build_packages(cls, package_names):
+    def install_build_packages(cls, package_names, arch):
         """Install packages on the host required to build.
 
         :param package_names: a list of package names to install.
         :type package_names: a list of strings.
+        :param str arch: the target architecture.
         :raises snapcraft.repo.errors.BuildPackageNotFoundError:
             if one of the package_names cannot be installed.
         """