3 files changed, 62 insertions, 0 deletions

diff --git a/Source/cmDocumentVariables.cxx b/Source/cmDocumentVariables.cxx
index 1cab2b5..f3125ce 100644
--- a/Source/cmDocumentVariables.cxx
+++ b/Source/cmDocumentVariables.cxx
@@ -746,6 +746,26 @@ void cmDocumentVariables::DefineVariables(cmake* cm)
      "Variables That Change Behavior");
 
   cm->DefineProperty
+    ("CMAKE_FIND_PACKAGE_WARN_NO_MODULE", cmProperty::VARIABLE,
+     "Tell find_package to warn if called without an explicit mode.",
+     "If find_package is called without an explicit mode option "
+     "(MODULE, CONFIG or NO_MODULE) and no Find<pkg>.cmake module is "
+     "in CMAKE_MODULE_PATH then CMake implicitly assumes that the "
+     "caller intends to search for a package configuration file.  "
+     "If no package configuration file is found then the wording "
+     "of the failure message must account for both the case that the "
+     "package is really missing and the case that the project has a "
+     "bug and failed to provide the intended Find module.  "
+     "If instead the caller specifies an explicit mode option then "
+     "the failure message can be more specific."
+     "\n"
+     "Set CMAKE_FIND_PACKAGE_WARN_NO_MODULE to TRUE to tell find_package "
+     "to warn when it implicitly assumes Config mode.  "
+     "This helps developers enforce use of an explicit mode in all calls "
+     "to find_package within a project.", false,
+     "Variables That Change Behavior");
+
+  cm->DefineProperty
     ("CMAKE_USER_MAKE_RULES_OVERRIDE", cmProperty::VARIABLE,
      "Specify a CMake file that overrides platform information.",
      "CMake loads the specified file while enabling support for each "
diff --git a/Source/cmFindPackageCommand.cxx b/Source/cmFindPackageCommand.cxx
index 437f47a..d632570 100644
--- a/Source/cmFindPackageCommand.cxx
+++ b/Source/cmFindPackageCommand.cxx
@@ -73,6 +73,7 @@ cmFindPackageCommand::cmFindPackageCommand()
   this->VersionFoundPatch = 0;
   this->VersionFoundTweak = 0;
   this->VersionFoundCount = 0;
+  this->RequiredCMakeVersion = 0;
 }
 
 //----------------------------------------------------------------------------
@@ -372,6 +373,15 @@ bool cmFindPackageCommand
     return false;
     }
 
+  // Lookup required version of CMake.
+  if(const char* rv =
+     this->Makefile->GetDefinition("CMAKE_MINIMUM_REQUIRED_VERSION"))
+    {
+    unsigned int v[3] = {0,0,0};
+    sscanf(rv, "%u.%u.%u", &v[0], &v[1], &v[2]);
+    this->RequiredCMakeVersion = CMake_VERSION_ENCODE(v[0],v[1],v[2]);
+    }
+
   // Check for debug mode.
   this->DebugMode = this->Makefile->IsOn("CMAKE_FIND_DEBUG_MODE");
 
@@ -691,6 +701,37 @@ bool cmFindPackageCommand
       }
     }
 
+  if(this->UseFindModules && this->UseConfigFiles &&
+     this->Makefile->IsOn("CMAKE_FIND_PACKAGE_WARN_NO_MODULE"))
+    {
+    cmOStringStream aw;
+    if(this->RequiredCMakeVersion >= CMake_VERSION_ENCODE(2,8,8))
+      {
+      aw << "find_package called without either MODULE or CONFIG option and "
+        "no Find" << this->Name << ".cmake module is in CMAKE_MODULE_PATH.  "
+        "Add MODULE to exclusively request Module mode and fail if "
+        "Find" << this->Name << ".cmake is missing.  "
+        "Add CONFIG to exclusively request Config mode and search for a "
+        "package configuration file provided by " << this->Name <<
+        " (" << this->Name << "Config.cmake or " <<
+        cmSystemTools::LowerCase(this->Name) << "-config.cmake).  ";
+      }
+    else
+      {
+      aw << "find_package called without NO_MODULE option and no "
+        "Find" << this->Name << ".cmake module is in CMAKE_MODULE_PATH.  "
+        "Add NO_MODULE to exclusively request Config mode and search for a "
+        "package configuration file provided by " << this->Name <<
+        " (" << this->Name << "Config.cmake or " <<
+        cmSystemTools::LowerCase(this->Name) << "-config.cmake).  "
+        "Otherwise make Find" << this->Name << ".cmake available in "
+        "CMAKE_MODULE_PATH.";
+      }
+    aw << "\n"
+      "(Variable CMAKE_FIND_PACKAGE_WARN_NO_MODULE enabled this warning.)";
+    this->Makefile->IssueMessage(cmake::AUTHOR_WARNING, aw.str());
+    }
+
   // No find module.  Assume the project has a CMake config file.  Use
   // a <package>_DIR cache variable to locate it.
   this->Variable = this->Name;
diff --git a/Source/cmFindPackageCommand.h b/Source/cmFindPackageCommand.h
index 560df9b..7269749 100644
--- a/Source/cmFindPackageCommand.h
+++ b/Source/cmFindPackageCommand.h
@@ -130,6 +130,7 @@ private:
   unsigned int VersionFoundPatch;
   unsigned int VersionFoundTweak;
   unsigned int VersionFoundCount;
+  unsigned int RequiredCMakeVersion;
   bool Quiet;
   bool Required;
   bool Compatibility_1_6;