Merge topic 'DisableSwitchForFindPackage'

4a50b5f Add a basic test for CMAKE_DISABLE_FIND_PACKAGE_<package>
a66df08 Add documentation for the CMAKE_DISABLE_FIND_PACKAGE_<Name> switch
6e1d3ed Add a switch to disable a find_package() call completely

Source/cmDocumentVariables.cxx

@@ -718,6 +718,20 @@ void cmDocumentVariables::DefineVariables(cmake* cm)
      "CMAKE_SYSTEM_PREFIX_PATH.", false,
      "Variables That Change Behavior");
 
+  cm->DefineProperty
+    ("CMAKE_DISABLE_FIND_PACKAGE_<PackageName>", cmProperty::VARIABLE,
+     "Variable for disabling find_package() calls.",
+     "Every non-REQUIRED find_package() call in a project can be disabled "
+     "by setting the variable CMAKE_DISABLE_FIND_PACKAGE_<PackageName> to "
+     "TRUE. This can be used to build a project without an optional package, "
+     "although that package is installed.\n"
+     "This switch should be used during the initial CMake run. Otherwise if "
+     "the package has already been found in a previous CMake run, the "
+     "variables which have been stored in the cache will still be there. "
+     "In the case it is recommended to remove the cache variables for "
+     "this package from the cache using the cache editor or cmake -U", false,
+     "Variables That Change Behavior");
+
   cm->DefineProperty
     ("CMAKE_USER_MAKE_RULES_OVERRIDE", cmProperty::VARIABLE,
      "Specify a CMake file that overrides platform information.",

Source/cmFindPackageCommand.cxx

@@ -335,6 +335,10 @@ void cmFindPackageCommand::GenerateDocumentation()
   this->CommandDocumentation += this->GenericDocumentationPathsOrder;
   this->CommandDocumentation +=
     "\n"
+    "Every non-REQUIRED find_package() call can be disabled by setting the "
+    "variable CMAKE_DISABLE_FIND_PACKAGE_<package> to TRUE. See the "
+    "documentation for the CMAKE_DISABLE_FIND_PACKAGE_<package> variable for "
+    "more information.\n"
     "See the cmake_policy() command documentation for discussion of the "
     "NO_POLICY_SCOPE option."
     ;
@@ -607,6 +611,24 @@ bool cmFindPackageCommand
       }
     }
 
+  std::string disableFindPackageVar = "CMAKE_DISABLE_FIND_PACKAGE_";
+  disableFindPackageVar += this->Name;
+  if(this->Makefile->IsOn(disableFindPackageVar.c_str()))
+    {
+    if (this->Required)
+      {
+      cmOStringStream e;
+      e << "for module " << this->Name << " called with REQUIRED, but "
+        << disableFindPackageVar
+        << " is enabled. A REQUIRED package cannot be disabled.";
+      this->SetError(e.str().c_str());
+      return false;
+      }
+
+    return true;
+    }
+
+
   this->SetModuleVariables(components);
 
   // See if there is a Find<package>.cmake module.

Tests/FindPackageTest/CMakeLists.txt

@@ -75,7 +75,7 @@ ENDIF()
 
 # For purposes of the test wipe out previous find results.
 SET(PACKAGES
-  foo Foo Bar TFramework Tframework TApp Tapp Special
+  foo Foo Bar Blub TFramework Tframework TApp Tapp Special
   VersionedA VersionedB VersionedC VersionedD VersionedE
   WrongA WrongB WrongC WrongD
   wibbleA wibbleB
@@ -104,6 +104,8 @@ set(CMAKE_IGNORE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/lib/cmake/zot-3.1)
 FIND_PACKAGE(foo NO_MODULE)
 FIND_PACKAGE(Foo CONFIGS FooConfig.cmake)
 FIND_PACKAGE(Bar)
+SET(CMAKE_DISABLE_FIND_PACKAGE_Blub TRUE)
+FIND_PACKAGE(Blub NO_MODULE)
 FIND_PACKAGE(TFramework CONFIGS TFrameworkConfig.cmake)
 FIND_PACKAGE(Tframework)
 FIND_PACKAGE(TApp)
@@ -169,6 +171,7 @@ ENDIF()
 SET(foo_EXPECTED "lib/foo-1.2/foo-config.cmake")
 SET(Foo_EXPECTED "lib/foo-1.2/CMake/FooConfig.cmake")
 SET(Bar_EXPECTED "lib/Bar/BarConfig.cmake")
+SET(Blub_MISSING "")
 SET(Special_EXPECTED "lib/suffix/test/SuffixTestConfig.cmake")
 SET(TFramework_EXPECTED
   "TFramework.framework/Versions/A/Resources/CMake/TFrameworkConfig.cmake")

Tests/FindPackageTest/lib/Blub/BlubConfig.cmake

@@ -0,0 +1 @@
+# Test config file.