wrf: Fix compilation with GCC 10+ (#35177)

Flags `-fallow-argument-mismatch -fallow-invalid-boz` set in `FFLAGS`/`FCFLAGS`
environment variables don't really have effect in older versions of WRF, we need
to force them in the compiler wrappers.

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

1 files changed, 11 insertions, 1 deletions

diff --git a/var/spack/repos/builtin/packages/wrf/package.py b/var/spack/repos/builtin/packages/wrf/package.py
index f197d9b956..1318a4367d 100644
--- a/var/spack/repos/builtin/packages/wrf/package.py
+++ b/var/spack/repos/builtin/packages/wrf/package.py
@@ -229,7 +229,10 @@ class Wrf(Package):
         env.set("JASPERINC", self.spec["jasper"].prefix.include)
         env.set("JASPERLIB", self.spec["jasper"].prefix.lib)
 
-        if self.spec.satisfies("%gcc@10:"):
+        # These flags should be used also in v3, but FCFLAGS/FFLAGS aren't used
+        # consistently in that version of WRF, so we have to force them through
+        # `flag_handler` below.
+        if self.spec.satisfies("@4.0: %gcc@10:"):
             args = "-w -O2 -fallow-argument-mismatch -fallow-invalid-boz"
             env.set("FCFLAGS", args)
             env.set("FFLAGS", args)
@@ -239,6 +242,13 @@ class Wrf(Package):
             env.set("HDF5", self.spec["hdf5"].prefix)
             env.prepend_path("PATH", ancestor(self.compiler.cc))
 
+    def flag_handler(self, name, flags):
+        # Same flags as FCFLAGS/FFLAGS above, but forced through the compiler
+        # wrapper when compiling v3.9.1.1.
+        if self.spec.satisfies("@3.9.1.1 %gcc@10:") and name == "fflags":
+            flags.extend(["-w", "-O2", "-fallow-argument-mismatch", "-fallow-invalid-boz"])
+        return (flags, None, None)
+
     def patch(self):
         # Let's not assume csh is intalled in bin
         files = glob.glob("*.csh")