Allow secondary generators when building with CMake. (#9324)

CMake supports the notion of secondary generators which provide extra
information to (e.g.) IDEs over and above that normally provided by
the primary generator. Spack only supports the 'Unix Makefiles' and
'Ninja' primary generators but was not parsing out the primary
generator when a secondary generator was also included (e.g. for
a generator attribute like 'Codeblocks - Ninja'). This adds a regex
for extracting the primary generator for validation.

Since the secondary generator is irrelevant to a Spack build, it is
passed on to CMake without further validation.

lib/spack/spack/build_systems/cmake.py

@@ -7,13 +7,27 @@
 import inspect
 import os
 import platform
+import re
 
 import spack.build_environment
 from llnl.util.filesystem import working_dir
 from spack.util.environment import filter_system_paths
 from spack.directives import depends_on, variant
 from spack.package import PackageBase, InstallError, run_after
 
+# Regex to extract the primary generator from the CMake generator
+# string.
+_primary_generator_extractor = re.compile(r'(?:.* - )?(.*)')
+
+
+def _extract_primary_generator(generator):
+    """Use the compiled regex _primary_generator_extractor to extract the
+    primary generator from the generator string which may contain an
+    optional secondary generator.
+    """
+    primary_generator = _primary_generator_extractor.match(generator).group(1)
+    return primary_generator
+
 
 class CMakePackage(PackageBase):
     """Specialized class for packages built using CMake
@@ -42,6 +56,17 @@ class CMakePackage(PackageBase):
         +-----------------------------------------------+--------------------+
 
 
+    The generator used by CMake can be specified by providing the
+    generator attribute. Per
+    https://cmake.org/cmake/help/git-master/manual/cmake-generators.7.html,
+    the format is: [<secondary-generator> - ]<primary_generator>. The
+    full list of primary and secondary generators supported by CMake may
+    be found in the documentation for the version of CMake used;
+    however, at this time Spack supports only the primary generators
+    "Unix Makefiles" and "Ninja." Spack's CMake support is agnostic with
+    respect to primary generators. Spack will generate a runtime error
+    if the generator string does not follow the prescribed format, or if
+    the primary generator is not supported.
     """
     #: Phases of a CMake package
     phases = ['cmake', 'build', 'install']
@@ -108,11 +133,13 @@ def _std_args(pkg):
             generator = 'Unix Makefiles'
 
         # Make sure a valid generator was chosen
-        valid_generators = ['Unix Makefiles', 'Ninja']
-        if generator not in valid_generators:
+        valid_primary_generators = ['Unix Makefiles', 'Ninja']
+        primary_generator = _extract_primary_generator(generator)
+        if primary_generator not in valid_primary_generators:
             msg  = "Invalid CMake generator: '{0}'\n".format(generator)
             msg += "CMakePackage currently supports the following "
-            msg += "generators: '{0}'".format("', '".join(valid_generators))
+            msg += "primary generators: '{0}'".\
+                   format("', '".join(valid_primary_generators))
             raise InstallError(msg)
 
         try:
@@ -124,9 +151,11 @@ def _std_args(pkg):
             '-G', generator,
             '-DCMAKE_INSTALL_PREFIX:PATH={0}'.format(pkg.prefix),
             '-DCMAKE_BUILD_TYPE:STRING={0}'.format(build_type),
-            '-DCMAKE_VERBOSE_MAKEFILE:BOOL=ON'
         ]
 
+        if primary_generator == 'Unix Makefiles':
+            args.append('-DCMAKE_VERBOSE_MAKEFILE:BOOL=ON')
+
         if platform.mac_ver()[0]:
             args.extend([
                 '-DCMAKE_FIND_FRAMEWORK:STRING=LAST',

lib/spack/spack/test/build_systems.py

@@ -115,6 +115,23 @@ def test_cmake_std_args(config, mock_packages):
     assert get_std_cmake_args(pkg)
 
 
+def test_cmake_bad_generator(config, mock_packages):
+    s = Spec('cmake-client')
+    s.concretize()
+    pkg = spack.repo.get(s)
+    pkg.generator = 'Yellow Sticky Notes'
+    with pytest.raises(spack.package.InstallError):
+        get_std_cmake_args(pkg)
+
+
+def test_cmake_secondary_generator(config, mock_packages):
+    s = Spec('cmake-client')
+    s.concretize()
+    pkg = spack.repo.get(s)
+    pkg.generator = 'CodeBlocks - Unix Makefiles'
+    assert get_std_cmake_args(pkg)
+
+
 @pytest.mark.usefixtures('config', 'mock_packages')
 class TestAutotoolsPackage(object):