Disallow language keyword for unsupported deps.

Also, document it in the manual.

2 files changed, 11 insertions, 2 deletions

diff --git a/mesonbuild/dependencies/__init__.py b/mesonbuild/dependencies/__init__.py
index fb57e3d..c16b92e 100644
--- a/mesonbuild/dependencies/__init__.py
+++ b/mesonbuild/dependencies/__init__.py
@@ -15,7 +15,7 @@
 from .base import (  # noqa: F401
     Dependency, DependencyException, DependencyMethods, ExternalProgram,
     ExternalDependency, ExternalLibrary, ExtraFrameworkDependency, InternalDependency,
-    PkgConfigDependency, find_external_dependency, get_dep_identifier, packages)
+    PkgConfigDependency, find_external_dependency, get_dep_identifier, packages, _packages_accept_language)
 from .dev import GMockDependency, GTestDependency, LLVMDependency, ValgrindDependency
 from .misc import (BoostDependency, MPIDependency, Python3Dependency, ThreadDependency)
 from .platform import AppleFrameworks
@@ -47,3 +47,6 @@ packages.update({
     'wxwidgets': WxDependency,
     'vulkan': VulkanDependency,
 })
+_packages_accept_language.update({
+    'mpi',
+})
diff --git a/mesonbuild/dependencies/base.py b/mesonbuild/dependencies/base.py
index f98de44..1f18c52 100644
--- a/mesonbuild/dependencies/base.py
+++ b/mesonbuild/dependencies/base.py
@@ -26,8 +26,9 @@ from .. import mesonlib
 from ..mesonlib import MesonException, Popen_safe, flatten, version_compare_many
 
 
-# This must be defined in this file to avoid cyclical references.
+# These must be defined in this file to avoid cyclical references.
 packages = {}
+_packages_accept_language = set()
 
 
 class DependencyException(MesonException):
@@ -610,10 +611,15 @@ def find_external_dependency(name, env, kwargs):
         raise DependencyException('Keyword "method" must be a string.')
     lname = name.lower()
     if lname in packages:
+        if lname not in _packages_accept_language and 'language' in kwargs:
+            raise DependencyException('%s dependency does not accept "language" keyword argument' % (lname, ))
         dep = packages[lname](env, kwargs)
         if required and not dep.found():
             raise DependencyException('Dependency "%s" not found' % name)
         return dep
+    if 'language' in kwargs:
+        # Remove check when PkgConfigDependency supports language.
+        raise DependencyException('%s dependency does not accept "language" keyword argument' % (lname, ))
     pkg_exc = None
     pkgdep = None
     try: