CachedCMakePackage for using *.cmake initial config files (#19316)"

Original commit message:
This feature of CMake allows packages to increase reproducibility, especially between
Spack- and manual builds. It also allows packages to sidestep certain parsing bugs in
extremely long ``cmake`` commands, and to avoid system limits on the length of the
command line.

Adding:
Co-authored by: Chris White <white238@llnl.gov>

This reverts commit c4f0a3cf6cd2ab282f6abf20fd72fcb4739a432a.

2 files changed, 253 insertions, 0 deletions

diff --git a/lib/spack/spack/build_systems/cached_cmake.py b/lib/spack/spack/build_systems/cached_cmake.py
new file mode 100644
index 0000000000..0704a4aa09
--- /dev/null
+++ b/lib/spack/spack/build_systems/cached_cmake.py
@@ -0,0 +1,249 @@
+# Copyright 2013-2021 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+import os
+
+from llnl.util.filesystem import install, mkdirp
+import llnl.util.tty as tty
+
+from spack.build_systems.cmake import CMakePackage
+from spack.package import run_after
+
+
+def cmake_cache_path(name, value, comment=""):
+    """Generate a string for a cmake cache variable"""
+    return 'set({0} "{1}" CACHE PATH "{2}")\n'.format(name, value, comment)
+
+
+def cmake_cache_string(name, value, comment=""):
+    """Generate a string for a cmake cache variable"""
+    return 'set({0} "{1}" CACHE STRING "{2}")\n'.format(name, value, comment)
+
+
+def cmake_cache_option(name, boolean_value, comment=""):
+    """Generate a string for a cmake configuration option"""
+
+    value = "ON" if boolean_value else "OFF"
+    return 'set({0} {1} CACHE BOOL "{2}")\n'.format(name, value, comment)
+
+
+class CachedCMakePackage(CMakePackage):
+    """Specialized class for packages built using CMake initial cache.
+
+    This feature of CMake allows packages to increase reproducibility,
+    especially between Spack- and manual builds. It also allows packages to
+    sidestep certain parsing bugs in extremely long ``cmake`` commands, and to
+    avoid system limits on the length of the command line."""
+
+    phases = ['initconfig', 'cmake', 'build', 'install']
+
+    @property
+    def cache_name(self):
+        return "{0}-{1}-{2}@{3}.cmake".format(
+            self.name,
+            self.spec.architecture,
+            self.spec.compiler.name,
+            self.spec.compiler.version,
+        )
+
+    @property
+    def cache_path(self):
+        return os.path.join(self.stage.source_path, self.cache_name)
+
+    def flag_handler(self, name, flags):
+        if name in ('cflags', 'cxxflags', 'cppflags', 'fflags'):
+            return (None, None, None)  # handled in the cmake cache
+        return (flags, None, None)
+
+    def initconfig_compiler_entries(self):
+        # This will tell cmake to use the Spack compiler wrappers when run
+        # through Spack, but use the underlying compiler when run outside of
+        # Spack
+        spec = self.spec
+
+        # Fortran compiler is optional
+        if "FC" in os.environ:
+            spack_fc_entry = cmake_cache_path(
+                "CMAKE_Fortran_COMPILER", os.environ['FC'])
+            system_fc_entry = cmake_cache_path(
+                "CMAKE_Fortran_COMPILER", self.compiler.fc)
+        else:
+            spack_fc_entry = "# No Fortran compiler defined in spec"
+            system_fc_entry = "# No Fortran compiler defined in spec"
+
+        entries = [
+            "#------------------{0}".format("-" * 60),
+            "# Compilers",
+            "#------------------{0}".format("-" * 60),
+            "# Compiler Spec: {0}".format(spec.compiler),
+            "#------------------{0}".format("-" * 60),
+            'if(DEFINED ENV{SPACK_CC})\n',
+            '  ' + cmake_cache_path(
+                "CMAKE_C_COMPILER", os.environ['CC']),
+            '  ' + cmake_cache_path(
+                "CMAKE_CXX_COMPILER", os.environ['CXX']),
+            '  ' + spack_fc_entry,
+            'else()\n',
+            '  ' + cmake_cache_path(
+                "CMAKE_C_COMPILER", self.compiler.cc),
+            '  ' + cmake_cache_path(
+                "CMAKE_CXX_COMPILER", self.compiler.cxx),
+            '  ' + system_fc_entry,
+            'endif()\n'
+        ]
+
+        # use global spack compiler flags
+        cppflags = ' '.join(spec.compiler_flags['cppflags'])
+        if cppflags:
+            # avoid always ending up with ' ' with no flags defined
+            cppflags += ' '
+        cflags = cppflags + ' '.join(spec.compiler_flags['cflags'])
+        if cflags:
+            entries.append(cmake_cache_string("CMAKE_C_FLAGS", cflags))
+        cxxflags = cppflags + ' '.join(spec.compiler_flags['cxxflags'])
+        if cxxflags:
+            entries.append(cmake_cache_string("CMAKE_CXX_FLAGS", cxxflags))
+        fflags = ' '.join(spec.compiler_flags['fflags'])
+        if fflags:
+            entries.append(cmake_cache_string("CMAKE_Fortran_FLAGS", fflags))
+
+        # Override XL compiler family
+        familymsg = ("Override to proper compiler family for XL")
+        if "xlf" in (self.compiler.fc or ''):  # noqa: F821
+            entries.append(cmake_cache_string(
+                "CMAKE_Fortran_COMPILER_ID", "XL",
+                familymsg))
+        if "xlc" in self.compiler.cc:  # noqa: F821
+            entries.append(cmake_cache_string(
+                "CMAKE_C_COMPILER_ID", "XL",
+                familymsg))
+        if "xlC" in self.compiler.cxx:  # noqa: F821
+            entries.append(cmake_cache_string(
+                "CMAKE_CXX_COMPILER_ID", "XL",
+                familymsg))
+
+        return entries
+
+    def initconfig_mpi_entries(self):
+        spec = self.spec
+
+        if "+mpi" not in spec:
+            return []
+
+        entries = [
+            "#------------------{0}".format("-" * 60),
+            "# MPI",
+            "#------------------{0}\n".format("-" * 60),
+        ]
+
+        entries.append(cmake_cache_path("MPI_C_COMPILER",
+                                        spec['mpi'].mpicc))
+        entries.append(cmake_cache_path("MPI_CXX_COMPILER",
+                                        spec['mpi'].mpicxx))
+        entries.append(cmake_cache_path("MPI_Fortran_COMPILER",
+                                        spec['mpi'].mpifc))
+
+        # Check for slurm
+        using_slurm = False
+        slurm_checks = ['+slurm',
+                        'schedulers=slurm',
+                        'process_managers=slurm']
+        if any(spec['mpi'].satisfies(variant) for variant in slurm_checks):
+            using_slurm = True
+
+        # Determine MPIEXEC
+        if using_slurm:
+            if spec['mpi'].external:
+                # Heuristic until we have dependents on externals
+                mpiexec = '/usr/bin/srun'
+            else:
+                mpiexec = os.path.join(spec['slurm'].prefix.bin, 'srun')
+        else:
+            mpiexec = os.path.join(spec['mpi'].prefix.bin, 'mpirun')
+            if not os.path.exists(mpiexec):
+                mpiexec = os.path.join(spec['mpi'].prefix.bin, 'mpiexec')
+
+        if not os.path.exists(mpiexec):
+            msg = "Unable to determine MPIEXEC, %s tests may fail" % self.name
+            entries.append("# {0}\n".format(msg))
+            tty.warn(msg)
+        else:
+            # starting with cmake 3.10, FindMPI expects MPIEXEC_EXECUTABLE
+            # vs the older versions which expect MPIEXEC
+            if self.spec["cmake"].satisfies('@3.10:'):
+                entries.append(cmake_cache_path("MPIEXEC_EXECUTABLE",
+                                                mpiexec))
+            else:
+                entries.append(cmake_cache_path("MPIEXEC", mpiexec))
+
+        # Determine MPIEXEC_NUMPROC_FLAG
+        if using_slurm:
+            entries.append(cmake_cache_string("MPIEXEC_NUMPROC_FLAG", "-n"))
+        else:
+            entries.append(cmake_cache_string("MPIEXEC_NUMPROC_FLAG", "-np"))
+
+        return entries
+
+    def initconfig_hardware_entries(self):
+        spec = self.spec
+
+        entries = [
+            "#------------------{0}".format("-" * 60),
+            "# Hardware",
+            "#------------------{0}\n".format("-" * 60),
+        ]
+
+        if '+cuda' in spec:
+            entries.append("#------------------{0}".format("-" * 30))
+            entries.append("# Cuda")
+            entries.append("#------------------{0}\n".format("-" * 30))
+
+            cudatoolkitdir = spec['cuda'].prefix
+            entries.append(cmake_cache_path("CUDA_TOOLKIT_ROOT_DIR",
+                                            cudatoolkitdir))
+            cudacompiler = "${CUDA_TOOLKIT_ROOT_DIR}/bin/nvcc"
+            entries.append(cmake_cache_path("CMAKE_CUDA_COMPILER",
+                                            cudacompiler))
+
+            if "+mpi" in spec:
+                entries.append(cmake_cache_path("CMAKE_CUDA_HOST_COMPILER",
+                                                "${MPI_CXX_COMPILER}"))
+            else:
+                entries.append(cmake_cache_path("CMAKE_CUDA_HOST_COMPILER",
+                                                "${CMAKE_CXX_COMPILER}"))
+
+        return entries
+
+    def std_initconfig_entries(self):
+        return [
+            "#------------------{0}".format("-" * 60),
+            "# !!!! This is a generated file, edit at own risk !!!!",
+            "#------------------{0}".format("-" * 60),
+            "# CMake executable path: {0}".format(
+                self.spec['cmake'].command.path),
+            "#------------------{0}\n".format("-" * 60),
+        ]
+
+    def initconfig(self, spec, prefix):
+        cache_entries = (self.std_initconfig_entries() +
+                         self.initconfig_compiler_entries() +
+                         self.initconfig_mpi_entries() +
+                         self.initconfig_hardware_entries() +
+                         self.initconfig_package_entries())
+
+        with open(self.cache_name, 'w') as f:
+            for entry in cache_entries:
+                f.write('%s\n' % entry)
+            f.write('\n')
+
+    @property
+    def std_cmake_args(self):
+        args = super(CachedCMakePackage, self).std_cmake_args
+        args.extend(['-C', self.cache_path])
+        return args
+
+    @run_after('install')
+    def install_cmake_cache(self):
+        mkdirp(self.spec.prefix.share.cmake)
+        install(self.cache_path, self.spec.prefix.share.cmake)
diff --git a/lib/spack/spack/pkgkit.py b/lib/spack/spack/pkgkit.py
index 133a581e20..bc44d0b7b2 100644
--- a/lib/spack/spack/pkgkit.py
+++ b/lib/spack/spack/pkgkit.py
@@ -19,6 +19,10 @@ from spack.build_systems.makefile import MakefilePackage
 from spack.build_systems.aspell_dict import AspellDictPackage
 from spack.build_systems.autotools import AutotoolsPackage
 from spack.build_systems.cmake import CMakePackage
+from spack.build_systems.cached_cmake import (
+    CachedCMakePackage, cmake_cache_option, cmake_cache_path,
+    cmake_cache_string
+)
 from spack.build_systems.cuda import CudaPackage
 from spack.build_systems.oneapi import IntelOneApiPackage
 from spack.build_systems.oneapi import IntelOneApiLibraryPackage