Change handling of not found external programs

mesonbuild/dependencies/__init__.py

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 from .base import (  # noqa: F401
-    Dependency, DependencyException, DependencyMethods, ExternalProgram,
+    Dependency, DependencyException, DependencyMethods, ExternalProgram, NonExistingExternalProgram,
     ExternalDependency, ExternalLibrary, ExtraFrameworkDependency, InternalDependency,
     PkgConfigDependency, find_external_dependency, get_dep_identifier, packages, _packages_accept_language)
 from .dev import GMockDependency, GTestDependency, LLVMDependency, ValgrindDependency

mesonbuild/dependencies/base.py

@@ -753,6 +753,17 @@ class ExternalProgram:
     def get_name(self):
         return self.name
 
+class NonExistingExternalProgram(ExternalProgram):
+
+    def __init__(self):
+        super().__init__(name = 'nonexistingprogram', silent = True)
+
+    def __repr__(self):
+        r = '<{} {!r} -> {!r}>'
+        return r.format(self.__class__.__name__, self.name, self.command)
+
+    def found(self):
+        return False
 
 class ExternalLibrary(ExternalDependency):
     def __init__(self, name, link_args, environment, language, silent=False):

mesonbuild/interpreter.py

@@ -2119,7 +2119,7 @@ to directly access options of other subprojects.''')
         if required and (progobj is None or not progobj.found()):
             raise InvalidArguments('Program "%s" not found or not executable' % args[0])
         if progobj is None:
-            return ExternalProgramHolder(dependencies.ExternalProgram('nonexistingprogram'))
+            return ExternalProgramHolder(dependencies.NonExistingExternalProgram())
         return progobj
 
     def func_find_library(self, node, args, kwargs):