dependencies/hdf5: Use the correct compilers for the machine

Instead of the default ones, this is especially important when cross
compiling or when using compilers that aren't compatible with the
default ones.
squash! dependencies/hdf5: Use the actual system compilers

docs/markdown/snippets/hdf5_dependnecy_improvements.md

@@ -4,3 +4,6 @@ HDF5 has been improved so that the internal representations have been split.
 This allows selecting pkg-config and config-tool dependencies separately.
 Both work as proper dependencies of their type, so `get_variable` and similar
 now work correctly.
+
+It has also been fixed to use the selected compiler for the build instead of
+the default compiler.

mesonbuild/coredata.py

@@ -390,7 +390,7 @@ class CoreData:
         ) # type: PerMachine[T.defaultdict[str, OptionDictType]]
         self.base_options = {} # type: OptionDictType
         self.cross_files = self.__load_config_files(options, scratch_dir, 'cross')
-        self.compilers = PerMachine(OrderedDict(), OrderedDict())
+        self.compilers = PerMachine(OrderedDict(), OrderedDict())  # type: PerMachine[T.Dict[str, Compiler]]
 
         build_cache = DependencyCache(self.builtins_per_machine, MachineChoice.BUILD)
         host_cache = DependencyCache(self.builtins_per_machine, MachineChoice.BUILD)

mesonbuild/dependencies/hdf5.py

@@ -15,12 +15,13 @@
 # This file contains the detection logic for miscellaneous external dependencies.
 
 import functools
-import subprocess
-import shutil
+import os
 import re
+import shutil
+import subprocess
 from pathlib import Path
 
-from ..mesonlib import OrderedSet
+from ..mesonlib import OrderedSet, join_args
 from .base import (
     DependencyException, DependencyMethods, ConfigToolDependency,
     PkgConfigDependency, factory_methods
@@ -94,10 +95,13 @@ class HDF5ConfigToolDependency(ConfigToolDependency):
             raise DependencyException('Language {} is not supported with HDF5.'.format(language))
 
         if language == 'c':
+            cenv = 'CC'
             tools = ['h5cc']
         elif language == 'cpp':
+            cenv = 'CXX'
             tools = ['h5c++']
         elif language == 'fortran':
+            cenv = 'FC'
             tools = ['h5fc']
         else:
             raise DependencyException('How did you get here?')
@@ -108,7 +112,17 @@ class HDF5ConfigToolDependency(ConfigToolDependency):
         nkwargs = kwargs.copy()
         nkwargs['tools'] = tools
 
+        # Override the compiler that the config tools are going to use by
+        # setting the environment variables that they use for the compiler and
+        # linkers.
+        compiler = environment.coredata.compilers[for_machine][language]
+        try:
+            os.environ['HDF5_{}'.format(cenv)] = join_args(compiler.get_exelist())
+            os.environ['HDF5_{}LINKER'.format(cenv)] = join_args(compiler.get_linker_exelist())
             super().__init__(name, environment, nkwargs, language)
+        finally:
+            del os.environ['HDF5_{}'.format(cenv)]
+            del os.environ['HDF5_{}LINKER'.format(cenv)]
         if not self.is_found:
             return
 
@@ -126,7 +140,7 @@ class HDF5ConfigToolDependency(ConfigToolDependency):
             nkwargs = kwargs.copy()
             nkwargs['language'] = 'c'
             # I'm being too clever for mypy and pylint
-            self.is_found = self._add_sub_dependency(hdf5_factory(environment, self.for_machine, nkwargs))  # type: ignore  # pylint: disable=no-value-for-parameter
+            self.is_found = self._add_sub_dependency(hdf5_factory(environment, for_machine, nkwargs))  # type: ignore  # pylint: disable=no-value-for-parameter
 
     def _sanitize_version(self, ver: str) -> str:
         v = re.search(r'\s*HDF5 Version: (\d+\.\d+\.\d+)', ver)