OpenBLAS 0.3.21: w/o Fortran (#32398)

There is a new OpenBLAS release out that can be compiled w/o
a Fortran compiler.

macOS XCode developers, rejoice. Maybe at some point Spack
becomes a package manager that can be used without using
another package manager (to get gfortran) 🎉

phist: add conflict on reference netlib-lapack due to API change in lapack.h

Co-authored-by: Harmen Stoppels <harmenstoppels@gmail.com>

var/spack/repos/builtin/packages/openblas/package.py

@@ -20,6 +20,7 @@ class Openblas(MakefilePackage):
     libraries = ["libopenblas"]
 
     version("develop", branch="develop")
+    version("0.3.21", sha256="f36ba3d7a60e7c8bcc54cd9aaa9b1223dd42eaf02c811791c37e8ca707c241ca")
     version("0.3.20", sha256="8495c9affc536253648e942908e88e097f2ec7753ede55aca52e5dead3029e3c")
     version("0.3.19", sha256="947f51bfe50c2a0749304fbe373e00e7637600b0a47b78a51382aeb30ca08562")
     version("0.3.18", sha256="1632c1e8cca62d8bed064b37747e331a1796fc46f688626337362bf0d16aeadb")
@@ -48,6 +49,13 @@ class Openblas(MakefilePackage):
     version("0.2.16", sha256="766f350d0a4be614812d535cead8c816fc3ad3b9afcd93167ea5e4df9d61869b")
     version("0.2.15", sha256="73c40ace5978282224e5e122a41c8388c5a19e65a6f2329c2b7c0b61bacc9044")
 
+    variant(
+        "fortran",
+        default="True",
+        when="@0.3.21:",
+        description="w/o a Fortran compiler, OpenBLAS will build an f2c-converted LAPACK",
+    )
+
     variant("ilp64", default=False, description="Force 64-bit Fortran native integers")
     variant("pic", default=True, description="Build position independent code")
     variant("shared", default=True, description="Build shared libraries")
@@ -208,7 +216,10 @@ def check_compilers(self):
         # As of 06/2016 there is no mechanism to specify that packages which
         # depends on Blas/Lapack need C or/and Fortran symbols. For now
         # require both.
-        if self.compiler.fc is None:
+        # As of 08/2022 (0.3.21), we can build purely with a C compiler using
+        # a f2c translated LAPACK version
+        #   https://github.com/xianyi/OpenBLAS/releases/tag/v0.3.21
+        if self.compiler.fc is None and "~fortran" not in self.spec:
             raise InstallError("OpenBLAS requires both C and Fortran compilers!")
 
     @staticmethod
@@ -313,10 +324,9 @@ def make_defs(self):
         # When mixing compilers make sure that
         # $SPACK_ROOT/lib/spack/env/<compiler> have symlinks with reasonable
         # names and hack them inside lib/spack/spack/compilers/<compiler>.py
-        make_defs = [
-            "CC={0}".format(spack_cc),
-            "FC={0}".format(spack_fc),
-        ]
+        make_defs = ["CC={0}".format(spack_cc)]
+        if "~fortran" not in self.spec:
+            make_defs += ["FC={0}".format(spack_fc)]
 
         # force OpenBLAS to use externally defined parallel build
         if self.spec.version < Version("0.3"):
@@ -327,14 +337,15 @@ def make_defs(self):
         # Add target and architecture flags
         make_defs += self._microarch_target_args()
 
+        # Fortran-free compilation
+        if "~fortran" in self.spec:
+            make_defs += ["NOFORTRAN=1"]
+
         if "~shared" in self.spec:
             if "+pic" in self.spec:
-                make_defs.extend(
-                    [
-                        "CFLAGS={0}".format(self.compiler.cc_pic_flag),
-                        "FFLAGS={0}".format(self.compiler.f77_pic_flag),
-                    ]
-                )
+                make_defs.append("CFLAGS={0}".format(self.compiler.cc_pic_flag))
+                if "~fortran" not in self.spec:
+                    make_defs.append("FFLAGS={0}".format(self.compiler.f77_pic_flag))
             make_defs += ["NO_SHARED=1"]
         # fix missing _dggsvd_ and _sggsvd_
         if self.spec.satisfies("@0.2.16"):

var/spack/repos/builtin/packages/phist/package.py

@@ -189,6 +189,14 @@ class Phist(CMakePackage):
     # and actual argument at (2) (scalar and rank-1)
     conflicts("%gcc@10:", when="@:1.9.0")
 
+    # reference lapack 3.9.1 (included in openblas 0.3.21) changed their lapack.h API
+    # to include trailing string lengths arguments in functions that have
+    # single-character strings as args. phist should be using the relevant
+    # LAPACK_function(...) macro's instead.
+    # https://bitbucket.org/essex/phist/issues/245/does-not-compile-with-reference-lapack-391
+    conflicts("^openblas@0.3.21:")
+    conflicts("^netlib-lapack@3.9.1:")
+
     # the phist repo came with it's own FindMPI.cmake before, which may cause some other
     # MPI installation to be used than the one spack wants.
     def patch(self):