Drop compatibility with CMake < 2.4

Drop all behavior activated by setting CMAKE_BACKWARDS_COMPATIBILITY to
a value lower than 2.4, and generate an error when projects or the user
attempt to do so.  In the error suggest using a CMake 2.8.x release.

Teach cmake_minimum_required to warn about projects that do not require
at least CMake 2.4.  They are not supported by CMake >= 3.0.

Replace the documentation of CMAKE_BACKWARDS_COMPATIBILITY with a
reference to policy CMP0001.

Help/variable/CMAKE_BACKWARDS_COMPATIBILITY.rst

@@ -1,11 +1,4 @@
 CMAKE_BACKWARDS_COMPATIBILITY
 -----------------------------
 
-Version of cmake required to build project
-
-From the point of view of backwards compatibility, this specifies what
-version of CMake should be supported.  By default this value is the
-version number of CMake that you are running.  You can set this to an
-older version of CMake to support deprecated commands of CMake in
-projects that were written to use older versions of CMake.  This can
-be set by the user or set at the beginning of a CMakeLists file.
+Deprecated.  See CMake Policy :policy:`CMP0001` documentation.

Modules/Platform/Darwin-icc.cmake

@@ -60,12 +60,6 @@ if(EXISTS /Developer/SDKs/MacOSX10.4u.sdk)
     CACHE STRING "Build architectures for OSX")
 endif()
 
-
-if("${CMAKE_BACKWARDS_COMPATIBILITY}" MATCHES "^1\\.[0-6]$")
-  set(CMAKE_SHARED_MODULE_CREATE_C_FLAGS
-    "${CMAKE_SHARED_MODULE_CREATE_C_FLAGS} -flat_namespace -undefined suppress")
-endif()
-
 if(NOT XCODE)
   # Enable shared library versioning.  This flag is not actually referenced
   # but the fact that the setting exists will cause the generators to support

Modules/Platform/Darwin.cmake

@@ -223,11 +223,6 @@ if(CMAKE_OSX_DEPLOYMENT_TARGET)
   endif()
 endif()
 
-if("${CMAKE_BACKWARDS_COMPATIBILITY}" MATCHES "^1\\.[0-6]$")
-  set(CMAKE_SHARED_MODULE_CREATE_C_FLAGS
-    "${CMAKE_SHARED_MODULE_CREATE_C_FLAGS} -flat_namespace -undefined suppress")
-endif()
-
 # Enable shared library versioning.
 set(CMAKE_SHARED_LIBRARY_SONAME_C_FLAG "-install_name")
 

Source/cmAddCustomTargetCommand.cxx

@@ -25,17 +25,12 @@ bool cmAddCustomTargetCommand
   // Check the target name.
   if(args[0].find_first_of("/\\") != args[0].npos)
     {
-    if(!this->Makefile->NeedBackwardsCompatibility(2,2))
-      {
-      cmOStringStream e;
-      e << "called with invalid target name \"" << args[0]
-        << "\".  Target names may not contain a slash.  "
-        << "Use ADD_CUSTOM_COMMAND to generate files.  "
-        << "Set CMAKE_BACKWARDS_COMPATIBILITY to 2.2 "
-        << "or lower to skip this check.";
-      this->SetError(e.str().c_str());
-      return false;
-      }
+    cmOStringStream e;
+    e << "called with invalid target name \"" << args[0]
+      << "\".  Target names may not contain a slash.  "
+      << "Use ADD_CUSTOM_COMMAND to generate files.";
+    this->SetError(e.str().c_str());
+    return false;
     }
 
   // Accumulate one command line at a time.

Source/cmCMakeMinimumRequired.cxx

@@ -114,6 +114,9 @@ bool cmCMakeMinimumRequired
 
   if (required_major < 2 || (required_major == 2 && required_minor < 4))
   {
+    this->Makefile->IssueMessage(
+      cmake::AUTHOR_WARNING,
+      "Compatibility with CMake < 2.4 is not supported by CMake >= 3.0.");
     this->Makefile->SetPolicyVersion("2.4");
   }
   else

Source/cmConfigureFileCommand.cxx

@@ -74,10 +74,6 @@ bool cmConfigureFileCommand
   this->CopyOnly = false;
   this->EscapeQuotes = false;
 
-  // for CMake 2.0 and earlier CONFIGURE_FILE defaults to the FinalPass,
-  // after 2.0 it only does InitialPass
-  this->Immediate = !this->Makefile->NeedBackwardsCompatibility(2,0);
-
   this->AtOnly = false;
   for(unsigned int i=2;i < args.size();++i)
     {
@@ -101,32 +97,19 @@ bool cmConfigureFileCommand
       }
     else if(args[i] == "IMMEDIATE")
       {
-      this->Immediate = true;
+      /* Ignore legacy option.  */
       }
     }
 
-  // If we were told to copy the file immediately, then do it on the
-  // first pass (now).
-  if(this->Immediate)
+  if ( !this->ConfigureFile() )
     {
-    if ( !this->ConfigureFile() )
-      {
-      this->SetError("Problem configuring file");
-      return false;
-      }
+    this->SetError("Problem configuring file");
+    return false;
     }
 
   return true;
 }
 
-void cmConfigureFileCommand::FinalPass()
-{
-  if(!this->Immediate)
-    {
-    this->ConfigureFile();
-    }
-}
-
 int cmConfigureFileCommand::ConfigureFile()
 {
   return this->Makefile->ConfigureFile(

Source/cmConfigureFileCommand.h

@@ -41,9 +41,6 @@ public:
    */
   virtual bool IsScriptable() const { return true; }
 
-  virtual void FinalPass();
-  virtual bool HasFinalPass() const { return !this->Immediate; }
-
 private:
   int ConfigureFile();
 
@@ -53,7 +50,6 @@ private:
   std::string OutputFile;
   bool CopyOnly;
   bool EscapeQuotes;
-  bool Immediate;
   bool AtOnly;
 };
 

Source/cmFindBase.cxx

@@ -28,11 +28,6 @@ bool cmFindBase::ParseArguments(std::vector<std::string> const& argsIn)
     return false;
     }
 
-  // CMake versions below 2.3 did not search all these extra
-  // locations.  Preserve compatibility unless a modern argument is
-  // passed.
-  bool compatibility = this->Makefile->NeedBackwardsCompatibility(2,3);
-
   // copy argsIn into args so it can be modified,
   // in the process extract the DOC "documentation"
   size_t size = argsIn.size();
@@ -112,7 +107,6 @@ bool cmFindBase::ParseArguments(std::vector<std::string> const& argsIn)
     else if (args[j] == "PATH_SUFFIXES")
       {
       doing = DoingPathSuffixes;
-      compatibility = false;
       newStyle = true;
       }
     else if (args[j] == "NAMES_PER_DIR")
@@ -136,7 +130,6 @@ bool cmFindBase::ParseArguments(std::vector<std::string> const& argsIn)
     else if (this->CheckCommonArgument(args[j]))
       {
       doing = DoingNone;
-      compatibility = false;
       // Some common arguments were accidentally supported by CMake
       // 2.4 and 2.6.0 in the short-hand form of the command, so we
       // must support it even though it is not documented.
@@ -159,17 +152,6 @@ bool cmFindBase::ParseArguments(std::vector<std::string> const& argsIn)
       }
     }
 
-  // Now that arguments have been parsed check the compatibility
-  // setting.  If we need to be compatible with CMake 2.2 and earlier
-  // do not add the CMake system paths.  It is safe to add the CMake
-  // environment paths and system environment paths because that
-  // existed in 2.2.  It is safe to add the CMake user variable paths
-  // because the user or project has explicitly set them.
-  if(compatibility)
-    {
-    this->NoCMakeSystemPath = true;
-    }
-
   if(this->VariableDocumentation.size() == 0)
     {
     this->VariableDocumentation = "Where can ";

Source/cmFindPackageCommand.cxx

@@ -24,32 +24,6 @@
 #include <StorageDefs.h>
 #endif
 
-void cmFindPackageNeedBackwardsCompatibility(const std::string& variable,
-  int access_type, void*, const char* newValue,
-  const cmMakefile*)
-{
-  (void)newValue;
-#ifdef CMAKE_BUILD_WITH_CMAKE
-  if(access_type == cmVariableWatch::UNKNOWN_VARIABLE_READ_ACCESS)
-    {
-    std::string message = "An attempt was made to access a variable: ";
-    message += variable;
-    message +=
-      " that has not been defined. This variable is created by the "
-      "FIND_PACKAGE command. CMake version 1.6 always converted the "
-      "variable name to upper-case, but this behavior is no longer the "
-      "case.  To fix this you might need to set the cache value of "
-      "CMAKE_BACKWARDS_COMPATIBILITY to 1.6 or less.  If you are writing a "
-      "CMake listfile, you should change the variable reference to use "
-      "the case of the argument to FIND_PACKAGE.";
-    cmSystemTools::Error(message.c_str());
-    }
-#else
-  (void)variable;
-  (void)access_type;
-#endif
-}
-
 //----------------------------------------------------------------------------
 cmFindPackageCommand::cmFindPackageCommand()
 {
@@ -128,11 +102,6 @@ bool cmFindPackageCommand
   std::set<std::string> requiredComponents;
   std::set<std::string> optionalComponents;
 
-  // Check ancient compatibility.
-  this->Compatibility_1_6 =
-    this->Makefile->GetLocalGenerator()
-    ->NeedBackwardsCompatibility(1, 6);
-
   // Always search directly in a generated path.
   this->SearchPathSuffixes.push_back("");
 
@@ -154,7 +123,6 @@ bool cmFindPackageCommand
     else if(args[i] == "EXACT")
       {
       this->VersionExact = true;
-      this->Compatibility_1_6 = false;
       doing = DoingNone;
       }
     else if(args[i] == "MODULE")
@@ -179,75 +147,63 @@ bool cmFindPackageCommand
       }
     else if(args[i] == "COMPONENTS")
       {
-      this->Compatibility_1_6 = false;
       doing = DoingComponents;
       }
     else if(args[i] == "OPTIONAL_COMPONENTS")
       {
-      this->Compatibility_1_6 = false;
       doing = DoingOptionalComponents;
       }
     else if(args[i] == "NAMES")
       {
       configArgs.insert(i);
-      this->Compatibility_1_6 = false;
       doing = DoingNames;
       }
     else if(args[i] == "PATHS")
       {
       configArgs.insert(i);
-      this->Compatibility_1_6 = false;
       doing = DoingPaths;
       }
     else if(args[i] == "HINTS")
       {
       configArgs.insert(i);
-      this->Compatibility_1_6 = false;
       doing = DoingHints;
       }
     else if(args[i] == "PATH_SUFFIXES")
       {
       configArgs.insert(i);
-      this->Compatibility_1_6 = false;
       doing = DoingPathSuffixes;
       }
     else if(args[i] == "CONFIGS")
       {
       configArgs.insert(i);
-      this->Compatibility_1_6 = false;
       doing = DoingConfigs;
       }
     else if(args[i] == "NO_POLICY_SCOPE")
       {
       this->PolicyScope = false;
-      this->Compatibility_1_6 = false;
       doing = DoingNone;
       }
     else if(args[i] == "NO_CMAKE_PACKAGE_REGISTRY")
       {
       this->NoUserRegistry = true;
       configArgs.insert(i);
-      this->Compatibility_1_6 = false;
       doing = DoingNone;
       }
     else if(args[i] == "NO_CMAKE_SYSTEM_PACKAGE_REGISTRY")
       {
       this->NoSystemRegistry = true;
       configArgs.insert(i);
-      this->Compatibility_1_6 = false;
       doing = DoingNone;
       }
     else if(args[i] == "NO_CMAKE_BUILDS_PATH")
       {
       this->NoBuilds = true;
       configArgs.insert(i);
-      this->Compatibility_1_6 = false;
       doing = DoingNone;
       }
     else if(this->CheckCommonArgument(args[i]))
       {
       configArgs.insert(i);
-      this->Compatibility_1_6 = false;
       doing = DoingNone;
       }
     else if((doing == DoingComponents) || (doing == DoingOptionalComponents))
@@ -642,24 +598,9 @@ bool cmFindPackageCommand::HandlePackageMode()
   std::string upperFound = cmSystemTools::UpperCase(this->Name);
   upperDir += "_DIR";
   upperFound += "_FOUND";
-  if(upperDir == this->Variable)
-    {
-    this->Compatibility_1_6 = false;
-    }
 
   // Try to find the config file.
   const char* def = this->Makefile->GetDefinition(this->Variable.c_str());
-  if(this->Compatibility_1_6 && cmSystemTools::IsOff(def))
-    {
-    // Use the setting of the old name of the variable to provide the
-    // value of the new.
-    const char* oldDef = this->Makefile->GetDefinition(upperDir.c_str());
-    if(!cmSystemTools::IsOff(oldDef))
-      {
-      this->Makefile->AddDefinition(this->Variable.c_str(), oldDef);
-      def = this->Makefile->GetDefinition(this->Variable.c_str());
-      }
-    }
 
   // Try to load the config file if the directory is known
   bool fileFound = false;
@@ -881,43 +822,6 @@ bool cmFindPackageCommand::HandlePackageMode()
     this->Makefile->RemoveDefinition(fileVar.c_str());
     }
 
-  // Handle some ancient compatibility stuff.
-  if(this->Compatibility_1_6)
-    {
-    // Listfiles will be looking for the capitalized version of the
-    // name.  Provide it.
-    this->Makefile->AddDefinition
-      (upperDir.c_str(),
-       this->Makefile->GetDefinition(this->Variable.c_str()));
-    this->Makefile->AddDefinition
-      (upperFound.c_str(),
-       this->Makefile->GetDefinition(foundVar.c_str()));
-    }
-
-#ifdef CMAKE_BUILD_WITH_CMAKE
-  if(!(upperDir == this->Variable))
-    {
-    if(this->Compatibility_1_6)
-      {
-      // Listfiles may use the capitalized version of the name.
-      // Remove any previously added watch.
-      this->Makefile->GetVariableWatch()->RemoveWatch(
-        upperDir.c_str(),
-        cmFindPackageNeedBackwardsCompatibility
-        );
-      }
-    else
-      {
-      // Listfiles should not be using the capitalized version of the
-      // name.  Add a watch to warn the user.
-      this->Makefile->GetVariableWatch()->AddWatch(
-        upperDir.c_str(),
-        cmFindPackageNeedBackwardsCompatibility
-        );
-      }
-    }
-#endif
-
   std::string consideredConfigsVar = this->Name;
   consideredConfigsVar += "_CONSIDERED_CONFIGS";
   std::string consideredVersionsVar = this->Name;

Source/cmFindPackageCommand.h

@@ -117,7 +117,6 @@ private:
   unsigned int RequiredCMakeVersion;
   bool Quiet;
   bool Required;
-  bool Compatibility_1_6;
   bool UseConfigFiles;
   bool UseFindModules;
   bool NoUserRegistry;

Source/cmGlobalGenerator.cxx

@@ -624,29 +624,6 @@ cmGlobalGenerator::EnableLanguage(std::vector<std::string>const& languages,
           {
           cmSystemTools::RemoveFile(compilerLangFile.c_str());
           }
-        else
-          {
-          // load backwards compatibility stuff for C and CXX
-          // for old versions of CMake ListFiles C and CXX had some
-          // backwards compatibility files they have to load
-          // These files have a bunch of try compiles in them so
-          // should only be done
-          if (mf->NeedBackwardsCompatibility(1,4))
-            {
-            if(strcmp(lang, "C") == 0)
-              {
-              ifpath =
-                mf->GetModulesFile("CMakeBackwardCompatibilityC.cmake");
-              mf->ReadListFile(0,ifpath.c_str());
-              }
-            if(strcmp(lang, "CXX") == 0)
-              {
-              ifpath =
-                mf->GetModulesFile("CMakeBackwardCompatibilityCXX.cmake");
-              mf->ReadListFile(0,ifpath.c_str());
-              }
-            }
-          }
         } // end if in try compile
       } // end need test language
     // Store the shared library flags so that we can satisfy CMP0018

Source/cmLocalGenerator.cxx

@@ -1412,13 +1412,6 @@ void cmLocalGenerator::GetIncludeDirectories(std::vector<std::string>& dirs,
     includeBinaryDir = true;
     }
 
-  // CMake versions below 2.0 would add the source tree to the -I path
-  // automatically.  Preserve compatibility.
-  if(this->NeedBackwardsCompatibility(1,9))
-    {
-    includeSourceDir = true;
-    }
-
   // Hack for VTK 4.0 - 4.4 which depend on the old behavior but do
   // not set the backwards compatibility level automatically.
   const char* vtkSourceDir =
@@ -3071,7 +3064,7 @@ cmLocalGenerator
     // Decide whether this language wants to replace the source
     // extension with the object extension.  For CMake 2.4
     // compatibility do this by default.
-    bool replaceExt = this->NeedBackwardsCompatibility(2, 4);
+    bool replaceExt = this->NeedBackwardsCompatibility_2_4();
     if(!replaceExt)
       {
       if(const char* lang = source.GetLanguage())
@@ -3318,9 +3311,7 @@ unsigned int cmLocalGenerator::GetBackwardsCompatibility()
 }
 
 //----------------------------------------------------------------------------
-bool cmLocalGenerator::NeedBackwardsCompatibility(unsigned int major,
-                                                  unsigned int minor,
-                                                  unsigned int patch)
+bool cmLocalGenerator::NeedBackwardsCompatibility_2_4()
 {
   // Check the policy to decide whether to pay attention to this
   // variable.
@@ -3348,7 +3339,7 @@ bool cmLocalGenerator::NeedBackwardsCompatibility(unsigned int major,
   // equal to or lower than the given version.
   unsigned int actual_compat = this->GetBackwardsCompatibility();
   return (actual_compat &&
-          actual_compat <= CMake_VERSION_ENCODE(major, minor, patch));
+          actual_compat <= CMake_VERSION_ENCODE(2, 4, 255));
 }
 
 //----------------------------------------------------------------------------

Source/cmLocalGenerator.h

@@ -324,9 +324,7 @@ public:
   /**
    * Test whether compatibility is set to a given version or lower.
    */
-  bool NeedBackwardsCompatibility(unsigned int major,
-                                  unsigned int minor,
-                                  unsigned int patch = 0xFFu);
+  bool NeedBackwardsCompatibility_2_4();
 
   /**
    * Generate a Mac OS X application bundle Info.plist file.

Source/cmMakefile.cxx

@@ -799,22 +799,6 @@ void cmMakefile::SetLocalGenerator(cmLocalGenerator* lg)
   this->CheckSystemVars = this->GetCMakeInstance()->GetCheckSystemVars();
 }
 
-bool cmMakefile::NeedBackwardsCompatibility(unsigned int major,
-                                            unsigned int minor,
-                                            unsigned int patch)
-{
-  if(this->LocalGenerator)
-    {
-    return
-      this->LocalGenerator->NeedBackwardsCompatibility(major, minor, patch);
-    }
-  else
-    {
-    return false;
-    }
-}
-
-
 namespace
 {
   struct file_not_persistent
@@ -871,13 +855,15 @@ void cmMakefile::ConfigureFinalPass()
   this->FinalPass();
   const char* oldValue
     = this->GetDefinition("CMAKE_BACKWARDS_COMPATIBILITY");
-  if (oldValue && atof(oldValue) <= 1.2)
+  if (oldValue && cmSystemTools::VersionCompare(
+        cmSystemTools::OP_LESS, oldValue, "2.4"))
     {
-    cmSystemTools::Error("You have requested backwards compatibility "
-                         "with CMake version 1.2 or earlier. This version "
-                         "of CMake only supports backwards compatibility "
-                         "with CMake 1.4 or later. For compatibility with "
-                         "1.2 or earlier please use CMake 2.0");
+    this->IssueMessage(
+      cmake::FATAL_ERROR,
+      "You have set CMAKE_BACKWARDS_COMPATIBILITY to a CMake version less "
+      "than 2.4. This version of CMake only supports backwards compatibility "
+      "with CMake 2.4 or later. For compatibility with older versions please "
+      "use any CMake 2.8.x release or lower.");
     }
   for (cmTargets::iterator l = this->Targets.begin();
        l != this->Targets.end(); l++)
@@ -1456,8 +1442,6 @@ void cmMakefile::AddLinkLibraryForTarget(const char *target,
       this->GetCMakeInstance()->GetGlobalGenerator()->FindTarget(0,lib);
     if(tgt)
       {
-      // CMake versions below 2.4 allowed linking to modules.
-      bool allowModules = this->NeedBackwardsCompatibility(2,2);
       // if it is not a static or shared library then you can not link to it
       if(!((tgt->GetType() == cmTarget::STATIC_LIBRARY) ||
            (tgt->GetType() == cmTarget::SHARED_LIBRARY) ||
@@ -1470,24 +1454,7 @@ void cmMakefile::AddLinkLibraryForTarget(const char *target,
           << " may not be linked into another target.  "
           << "One may link only to STATIC or SHARED libraries, or "
           << "to executables with the ENABLE_EXPORTS property set.";
-        // in older versions of cmake linking to modules was allowed
-        if( tgt->GetType() == cmTarget::MODULE_LIBRARY )
-          {
-          e << "\n"
-            << "If you are developing a new project, re-organize it to avoid "
-            << "linking to modules.  "
-            << "If you are just trying to build an existing project, "
-            << "set CMAKE_BACKWARDS_COMPATIBILITY to 2.2 or lower to allow "
-            << "linking to modules.";
-          }
-        // if no modules are allowed then this is always an error
-        if(!allowModules ||
-           // if we allow modules but the type is not a module then it is
-           // still an error
-           (allowModules && tgt->GetType() != cmTarget::MODULE_LIBRARY))
-          {
-          this->IssueMessage(cmake::FATAL_ERROR, e.str().c_str());
-          }
+        this->IssueMessage(cmake::FATAL_ERROR, e.str().c_str());
         }
       }
     i->second.AddLinkLibrary( *this, target, lib, llt );

Source/cmMakefile.h

@@ -145,13 +145,6 @@ public:
   cmLocalGenerator* GetLocalGenerator()
     { return this->LocalGenerator;}
 
-  /**
-   * Test whether compatibility is set to a given version or lower.
-   */
-  bool NeedBackwardsCompatibility(unsigned int major,
-                                  unsigned int minor,
-                                  unsigned int patch = 0xFFu);
-
   /**
    * Help enforce global target name uniqueness.
    */

Source/cmPolicies.cxx

@@ -357,15 +357,9 @@ bool cmPolicies::ApplyPolicyVersion(cmMakefile *mf,
   if (majorVer < 2 || (majorVer == 2 && minorVer < 4))
     {
     mf->IssueMessage(cmake::FATAL_ERROR,
-      "An attempt was made to set the policy version of CMake to something "
-      "earlier than \"2.4\".  "
-      "In CMake 2.4 and below backwards compatibility was handled with the "
-      "CMAKE_BACKWARDS_COMPATIBILITY variable.  "
-      "In order to get compatibility features supporting versions earlier "
-      "than 2.4 set policy CMP0001 to OLD to tell CMake to check the "
-      "CMAKE_BACKWARDS_COMPATIBILITY variable.  "
-      "One way to do this is to set the policy version to 2.4 exactly."
-      );
+      "Compatibility with CMake < 2.4 is not supported by CMake >= 3.0.  "
+      "For compatibility with older versions please use any CMake 2.8.x "
+      "release or lower.");
     return false;
     }
 

Source/cmTarget.cxx

@@ -5376,11 +5376,9 @@ bool cmTarget::ComputeLinkInterface(const char* config, LinkInterface& iface,
 
   // There is no implicit link interface for executables or modules
   // so if none was explicitly set then there is no link interface.
-  // Note that CMake versions 2.2 and below allowed linking to modules.
-  bool canLinkModules = this->Makefile->NeedBackwardsCompatibility(2,2);
   if(!explicitLibraries &&
      (this->GetType() == cmTarget::EXECUTABLE ||
-      (this->GetType() == cmTarget::MODULE_LIBRARY && !canLinkModules)))
+      (this->GetType() == cmTarget::MODULE_LIBRARY)))
     {
     return false;
     }

Source/cmake.cxx

@@ -99,30 +99,6 @@
 static bool cmakeCheckStampFile(const char* stampName);
 static bool cmakeCheckStampList(const char* stampName);
 
-void cmNeedBackwardsCompatibility(const std::string& variable,
-  int access_type, void*, const char*, const cmMakefile*)
-{
-#ifdef CMAKE_BUILD_WITH_CMAKE
-  if (access_type == cmVariableWatch::UNKNOWN_VARIABLE_READ_ACCESS)
-    {
-    std::string message = "An attempt was made to access a variable: ";
-    message += variable;
-    message +=
-      " that has not been defined. Some variables were always defined "
-      "by CMake in versions prior to 1.6. To fix this you might need to set "
-      "the cache value of CMAKE_BACKWARDS_COMPATIBILITY to 1.4 or less. If "
-      "you are writing a CMakeLists file, (or have already set "
-      "CMAKE_BACKWARDS_COMPATIBILITY to 1.4 or less) then you probably need "
-      "to include a CMake module to test for the feature this variable "
-      "defines.";
-    cmSystemTools::Error(message.c_str());
-    }
-#else
-  (void)variable;
-  (void)access_type;
-#endif
-}
-
 void cmWarnUnusedCliWarning(const std::string& variable,
   int, void* ctx, const char*, const cmMakefile*)
 {
@@ -169,12 +145,6 @@ cmake::cmake()
 
 #ifdef CMAKE_BUILD_WITH_CMAKE
   this->VariableWatch = new cmVariableWatch;
-  this->VariableWatch->AddWatch("CMAKE_WORDS_BIGENDIAN",
-                            cmNeedBackwardsCompatibility);
-  this->VariableWatch->AddWatch("CMAKE_SIZEOF_INT",
-                            cmNeedBackwardsCompatibility);
-  this->VariableWatch->AddWatch("CMAKE_X_LIBS",
-                            cmNeedBackwardsCompatibility);
 #endif
 
   this->AddDefaultGenerators();

Tests/Complex/CMakeLists.txt

@@ -1,7 +1,7 @@
 #
 # A more complex test case
 #
-set(CMAKE_BACKWARDS_COMPATIBILITY 1.4)
+cmake_minimum_required(VERSION 2.4)
 project (Complex)
 
 # Try setting a new policy.  The IF test is for coverage.

Tests/Complex/Executable/CMakeLists.txt

@@ -1,4 +1,3 @@
-cmake_minimum_required(VERSION 1.3)
 #
 # Create exe.
 #

Tests/Complex/Executable/complex.cxx

@@ -838,13 +838,13 @@ int main()
 #endif
 #endif // defined(_WIN32) && !defined(__CYGWIN__)
 
-  if(strcmp(CMAKE_MINIMUM_REQUIRED_VERSION, "1.3") == 0)
+  if(strcmp(CMAKE_MINIMUM_REQUIRED_VERSION, "2.4") == 0)
     {
-    cmPassed("CMAKE_MINIMUM_REQUIRED_VERSION is set to 1.3");
+    cmPassed("CMAKE_MINIMUM_REQUIRED_VERSION is set to 2.4");
     }
   else
     {
-    cmFailed("CMAKE_MINIMUM_REQUIRED_VERSION is not set to the expected 1.3");
+    cmFailed("CMAKE_MINIMUM_REQUIRED_VERSION is not set to the expected 2.4");
     }
 
   // ----------------------------------------------------------------------

Tests/ComplexOneConfig/CMakeLists.txt

@@ -1,7 +1,7 @@
 #
 # A more complex test case
 #
-set(CMAKE_BACKWARDS_COMPATIBILITY 1.4)
+cmake_minimum_required(VERSION 2.4)
 project (Complex)
 
 # Try setting a new policy.  The IF test is for coverage.

Tests/ComplexOneConfig/Executable/CMakeLists.txt

@@ -1,4 +1,3 @@
-cmake_minimum_required(VERSION 1.3)
 #
 # Create exe.
 #

Tests/ComplexOneConfig/Executable/complex.cxx

@@ -838,13 +838,13 @@ int main()
 #endif
 #endif // defined(_WIN32) && !defined(__CYGWIN__)
 
-  if(strcmp(CMAKE_MINIMUM_REQUIRED_VERSION, "1.3") == 0)
+  if(strcmp(CMAKE_MINIMUM_REQUIRED_VERSION, "2.4") == 0)
     {
-    cmPassed("CMAKE_MINIMUM_REQUIRED_VERSION is set to 1.3");
+    cmPassed("CMAKE_MINIMUM_REQUIRED_VERSION is set to 2.4");
     }
   else
     {
-    cmFailed("CMAKE_MINIMUM_REQUIRED_VERSION is not set to the expected 1.3");
+    cmFailed("CMAKE_MINIMUM_REQUIRED_VERSION is not set to the expected 2.4");
     }
 
   // ----------------------------------------------------------------------

Tests/RunCMake/CMakeLists.txt

@@ -93,6 +93,7 @@ add_RunCMake_test(Syntax)
 
 add_RunCMake_test(add_dependencies)
 add_RunCMake_test(build_command)
+add_RunCMake_test(cmake_minimum_required)
 add_RunCMake_test(find_package)
 add_RunCMake_test(get_filename_component)
 add_RunCMake_test(if)

Tests/RunCMake/cmake_minimum_required/Before24-stderr.txt

@@ -0,0 +1,5 @@
+CMake Warning \(dev\) at Before24.cmake:1 \(cmake_minimum_required\):
+  Compatibility with CMake < 2.4 is not supported by CMake >= 3.0.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
+This warning is for project developers.  Use -Wno-dev to suppress it.

Tests/RunCMake/cmake_minimum_required/Before24.cmake

@@ -0,0 +1 @@
+cmake_minimum_required(VERSION 2.2)

Tests/RunCMake/cmake_minimum_required/CMakeLists.txt

@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 2.8)
+project(${RunCMake_TEST} NONE)
+include(${RunCMake_TEST}.cmake)

Tests/RunCMake/cmake_minimum_required/CompatBefore24-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/cmake_minimum_required/CompatBefore24-stderr.txt

@@ -0,0 +1,5 @@
+CMake Error in CMakeLists.txt:
+  You have set CMAKE_BACKWARDS_COMPATIBILITY to a CMake version less than
+  2.4.  This version of CMake only supports backwards compatibility with
+  CMake 2.4 or later.  For compatibility with older versions please use any
+  CMake 2.8.x release or lower.

Tests/RunCMake/cmake_minimum_required/CompatBefore24.cmake

@@ -0,0 +1,2 @@
+cmake_minimum_required(VERSION 2.4)
+set(CMAKE_BACKWARDS_COMPATIBILITY 2.2)

Tests/RunCMake/cmake_minimum_required/PolicyBefore24-result.txt

@@ -0,0 +1 @@
+1

Tests/RunCMake/cmake_minimum_required/PolicyBefore24-stderr.txt

@@ -0,0 +1,6 @@
+CMake Error at PolicyBefore24.cmake:2 \(cmake_policy\):
+  Compatibility with CMake < 2.4 is not supported by CMake >= 3.0.  For
+  compatibility with older versions please use any CMake 2.8.x release or
+  lower.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)

Tests/RunCMake/cmake_minimum_required/PolicyBefore24.cmake

@@ -0,0 +1,2 @@
+cmake_minimum_required(VERSION 2.4)
+cmake_policy(VERSION 2.2)

Tests/RunCMake/cmake_minimum_required/RunCMakeTest.cmake

@@ -0,0 +1,5 @@
+include(RunCMake)
+
+run_cmake(Before24)
+run_cmake(CompatBefore24)
+run_cmake(PolicyBefore24)