HDF5: Suppress promoted warning that causes build failure on clang and gcc (#23354)

* simplify compiler flag logic and suppress warning that gets promoted to an error on certain files in gcc/clang

1 files changed, 21 insertions, 16 deletions

diff --git a/var/spack/repos/builtin/packages/hdf5/package.py b/var/spack/repos/builtin/packages/hdf5/package.py
index d4c8b916ac..b51e5d9167 100644
--- a/var/spack/repos/builtin/packages/hdf5/package.py
+++ b/var/spack/repos/builtin/packages/hdf5/package.py
@@ -298,22 +298,6 @@ class Hdf5(AutotoolsPackage):
             extra_args.append('--disable-shared')
             extra_args.append('--enable-static-exec')
 
-        if '+pic' in self.spec:
-            # use global spack compiler flags
-            _flags = self.compiler.cc_pic_flag
-            _flags += " " + ' '.join(self.spec.compiler_flags['cflags'])
-            extra_args.append('CFLAGS={0}'.format(_flags))
-
-            if '+cxx' in self.spec:
-                _flags = self.compiler.cxx_pic_flag
-                _flags += " " + ' '.join(self.spec.compiler_flags['cxxflags'])
-                extra_args.append('CXXFLAGS={0}'.format(_flags))
-
-            if '+fortran' in self.spec:
-                _flags = self.compiler.fc_pic_flag
-                _flags += " " + ' '.join(self.spec.compiler_flags['fflags'])
-                extra_args.append('FCFLAGS={0}'.format(_flags))
-
         # Fujitsu Compiler does not add Fortran runtime in rpath.
         if '+fortran %fj' in self.spec:
             extra_args.append('LDFLAGS=-lfj90i -lfj90f -lfjsrcinfo -lelf')
@@ -333,6 +317,27 @@ class Hdf5(AutotoolsPackage):
             if '+fortran' in self.spec:
                 extra_args.append('FC=%s' % self.spec['mpi'].mpifc)
 
+        # Append package specific compiler flags to the global ones
+        cflags = ' '.join(self.spec.compiler_flags['cflags'])
+        cxxflags = ' '.join(self.spec.compiler_flags['cxxflags'])
+        fflags = ' '.join(self.spec.compiler_flags['fflags'])
+
+        if '+pic' in self.spec:
+            cflags += " " + self.compiler.cc_pic_flag
+            cxxflags += " " + self.compiler.cxx_pic_flag
+            fflags += " " + self.compiler.fc_pic_flag
+
+        # Quiet warnings/errors about implicit declaration of functions in C99
+        if "clang" in self.compiler.cc or "gcc" in self.compiler.cc:
+            cflags += " -Wno-implicit-function-declaration"
+
+        if cflags:
+            extra_args.append('CFLAGS={0}'.format(cflags))
+        if cxxflags and '+cxx' in self.spec:
+            extra_args.append('CXXFLAGS={0}'.format(cxxflags))
+        if fflags and '+fortran' in self.spec:
+            extra_args.append('FCFLAGS={0}'.format(fflags))
+
         return extra_args
 
     @run_after('configure')