dependency: log cached or skipped dependencies with reference to modules

* dependency: log cached or skipped dependencies with reference to modules

If the dependency is a special dependency which takes modules, the
modules get cached separately and probably reference different
pkg-config files. It's very plausible that we have multiple
dependencies, using different modules. For example:

  Run-time dependency qt5 (modules: Core) found: YES 5.14.2 (pkg-config)
  Dependency qt5 skipped: feature gui disabled

Obviously this makes no sense, because of course we found qt5 and even
used it. The second line is a lot more readable if it shows this:

  Dependency qt5 (modules: Widgets) skipped: feature gui disabled

Similar confusion abounds in the case where a module is found in the
cache -- which module, exactly, has been found here:

  Dependency qt5 found: YES 5.14.2 (cached)

Rewrite the dependency function to *consistently* pass around (and use!)
the display_name even in cases where we know it isn't anonymous (this is
just more correct anyway), and make it serve a dual purpose by also
appending the list of modules just like we do for pretty-printing that a
dependency has just been found for the first time.

* fixup! dependency: log cached or skipped dependencies with reference to modules

pointlessly cast modules to str, as they cannot be anything else. But we
want to fail later on, with something more friendly than a stacktrace.
boost/wx have special exceptions for people passing an integer there.

mesonbuild/interpreter.py

@@ -3282,7 +3282,7 @@ external dependencies (including libraries) must go to "dependencies".''')
                           'Look here for example: http://mesonbuild.com/howtox.html#add-math-library-lm-portably\n'
                           )
 
-    def _find_cached_dep(self, name, kwargs):
+    def _find_cached_dep(self, name, display_name, kwargs):
         # Check if we want this as a build-time / build machine or runt-time /
         # host machine dep.
         for_machine = self.machine_from_native_kwarg(kwargs)
@@ -3297,7 +3297,7 @@ external dependencies (including libraries) must go to "dependencies".''')
             # have explicitly called meson.override_dependency() with a not-found
             # dep.
             if not cached_dep.found():
-                mlog.log('Dependency', mlog.bold(name),
+                mlog.log('Dependency', mlog.bold(display_name),
                          'found:', mlog.red('NO'), *info)
                 return identifier, cached_dep
             found_vers = cached_dep.get_version()
@@ -3319,7 +3319,7 @@ external dependencies (including libraries) must go to "dependencies".''')
         if cached_dep:
             if found_vers:
                 info = [mlog.normal_cyan(found_vers), *info]
-            mlog.log('Dependency', mlog.bold(name),
+            mlog.log('Dependency', mlog.bold(display_name),
                      'found:', mlog.green('YES'), *info)
             return identifier, cached_dep
 
@@ -3352,7 +3352,7 @@ external dependencies (including libraries) must go to "dependencies".''')
         dep = self.notfound_dependency()
         try:
             subproject = self.subprojects[dirname]
-            _, cached_dep = self._find_cached_dep(name, kwargs)
+            _, cached_dep = self._find_cached_dep(name, display_name, kwargs)
             if varname is None:
                 # Assuming the subproject overridden the dependency we want
                 if cached_dep:
@@ -3425,6 +3425,9 @@ external dependencies (including libraries) must go to "dependencies".''')
         self.validate_arguments(args, 1, [str])
         name = args[0]
         display_name = name if name else '(anonymous)'
+        mods = extract_as_list(kwargs, 'modules')
+        if mods:
+            display_name += ' (modules: {})'.format(', '.join(str(i) for i in mods))
         not_found_message = kwargs.get('not_found_message', '')
         if not isinstance(not_found_message, str):
             raise InvalidArguments('The not_found_message must be a string.')
@@ -3466,7 +3469,7 @@ external dependencies (including libraries) must go to "dependencies".''')
             raise InvalidArguments('Characters <, > and = are forbidden in dependency names. To specify'
                                    'version\n requirements use the \'version\' keyword argument instead.')
 
-        identifier, cached_dep = self._find_cached_dep(name, kwargs)
+        identifier, cached_dep = self._find_cached_dep(name, display_name, kwargs)
         if cached_dep:
             if has_fallback:
                 dirname, varname = self.get_subproject_infos(kwargs)