ENH: Add if(TARGET) command

It is useful to be able to test if a target has been created.  Often
targets are created only inside conditions.  Rather than storing the
result of the condition manually for testing by other parts of the
project, it is much easier for the other parts to just test for the
target's existence.  This will also be useful when find-modules start
reporting results with IMPORTED targets and projects want to test if a
certain target is available.

Source/cmIfCommand.cxx

@@ -408,6 +408,13 @@ namespace
           makefile->GetPolicies()->GetPolicyID((argP1)->c_str(), pid),
           reducible, arg, newArgs, argP1, argP2);
         }
+      // does a target exist
+      if (*arg == "TARGET" && argP1 != newArgs.end())
+        {
+        HandlePredicate(
+          makefile->FindTargetToUse((argP1)->c_str())? true:false,
+          reducible, arg, newArgs, argP1, argP2);
+        }
       // is a variable defined
       if (*arg == "DEFINED" && argP1  != newArgs.end())
         {

Source/cmIfCommand.h

@@ -142,6 +142,8 @@ public:
       "  if(POLICY policy-id)\n"
       "True if the given name is an existing policy "
       "(of the form CMP<NNNN>).\n"
+      "  if(TARGET target-name)\n"
+      "True if the given name is an existing target, built or imported.\n"
       "  if(EXISTS file-name)\n"
       "  if(EXISTS directory-name)\n"
       "True if the named file or directory exists.  "

Tests/Complex/Executable/CMakeLists.txt

@@ -16,6 +16,23 @@ IF(COMPLEX_TEST_CMAKELIB)
   LINK_DIRECTORIES(${Complex_BINARY_DIR}/../../Utilities/cmtar)
 ENDIF(COMPLEX_TEST_CMAKELIB)
 
+# Create an imported target for if(TARGET) test below.
+ADD_LIBRARY(ExeImportedTarget UNKNOWN IMPORTED)
+
+# Test if(TARGET) command.
+IF(NOT TARGET CMakeTestLibrary)
+  MESSAGE(FATAL_ERROR "IF(NOT TARGET CMakeTestLibrary) returned true!")
+ENDIF(NOT TARGET CMakeTestLibrary)
+IF(NOT TARGET ExeImportedTarget)
+  MESSAGE(FATAL_ERROR "IF(NOT TARGET ExeImportedTarget) returned true!")
+ENDIF(NOT TARGET ExeImportedTarget)
+IF(TARGET LibImportedTarget)
+  MESSAGE(FATAL_ERROR "IF(TARGET LibImportedTarget) returned true!")
+ENDIF(TARGET LibImportedTarget)
+IF(TARGET NotATarget)
+  MESSAGE(FATAL_ERROR "IF(TARGET NotATarget) returned true!")
+ENDIF(TARGET NotATarget)
+
   # Use LINK_LIBRARIES instead of TARGET_LINK_LIBRARIES to 
 SET(COMPLEX_LIBS CMakeTestLibrary;CMakeTestLibraryShared;CMakeTestCLibraryShared)
 LINK_LIBRARIES(${COMPLEX_LIBS})

Tests/Complex/Library/CMakeLists.txt

@@ -114,6 +114,10 @@ INSTALL_FILES(/tmp .cxx ${Complex_BINARY_DIR}/cmTestConfigure.h)
 # Test creating a library that is not built by default.
 ADD_LIBRARY(notInAllLib EXCLUDE_FROM_ALL notInAllLib.cxx)
 
+# Create an imported target for if(TARGET) test in Executable dir.
+# That test should not see this target.
+ADD_LIBRARY(LibImportedTarget UNKNOWN IMPORTED)
+
 # Test generation of preprocessed sources.
 IF("${CMAKE_GENERATOR}" MATCHES "Makefile" AND CMAKE_MAKE_PROGRAM)
   IF(CMAKE_CXX_CREATE_PREPROCESSED_SOURCE)

Tests/ComplexOneConfig/Executable/CMakeLists.txt

@@ -16,6 +16,23 @@ IF(COMPLEX_TEST_CMAKELIB)
   LINK_DIRECTORIES(${Complex_BINARY_DIR}/../../Utilities/cmtar)
 ENDIF(COMPLEX_TEST_CMAKELIB)
 
+# Create an imported target for if(TARGET) test below.
+ADD_LIBRARY(ExeImportedTarget UNKNOWN IMPORTED)
+
+# Test if(TARGET) command.
+IF(NOT TARGET CMakeTestLibrary)
+  MESSAGE(FATAL_ERROR "IF(NOT TARGET CMakeTestLibrary) returned true!")
+ENDIF(NOT TARGET CMakeTestLibrary)
+IF(NOT TARGET ExeImportedTarget)
+  MESSAGE(FATAL_ERROR "IF(NOT TARGET ExeImportedTarget) returned true!")
+ENDIF(NOT TARGET ExeImportedTarget)
+IF(TARGET LibImportedTarget)
+  MESSAGE(FATAL_ERROR "IF(TARGET LibImportedTarget) returned true!")
+ENDIF(TARGET LibImportedTarget)
+IF(TARGET NotATarget)
+  MESSAGE(FATAL_ERROR "IF(TARGET NotATarget) returned true!")
+ENDIF(TARGET NotATarget)
+
   # Use LINK_LIBRARIES instead of TARGET_LINK_LIBRARIES to 
 SET(COMPLEX_LIBS CMakeTestLibrary;CMakeTestLibraryShared;CMakeTestCLibraryShared)
 LINK_LIBRARIES(${COMPLEX_LIBS})

Tests/ComplexOneConfig/Library/CMakeLists.txt

@@ -114,6 +114,10 @@ INSTALL_FILES(/tmp .cxx ${Complex_BINARY_DIR}/cmTestConfigure.h)
 # Test creating a library that is not built by default.
 ADD_LIBRARY(notInAllLib EXCLUDE_FROM_ALL notInAllLib.cxx)
 
+# Create an imported target for if(TARGET) test in Executable dir.
+# That test should not see this target.
+ADD_LIBRARY(LibImportedTarget UNKNOWN IMPORTED)
+
 # Test generation of preprocessed sources.
 IF("${CMAKE_GENERATOR}" MATCHES "Makefile" AND CMAKE_MAKE_PROGRAM)
   IF(CMAKE_CXX_CREATE_PREPROCESSED_SOURCE)

Tests/ComplexRelativePaths/Executable/CMakeLists.txt

@@ -16,6 +16,23 @@ IF(COMPLEX_TEST_CMAKELIB)
   LINK_DIRECTORIES(${Complex_BINARY_DIR}/../../Utilities/cmtar)
 ENDIF(COMPLEX_TEST_CMAKELIB)
 
+# Create an imported target for if(TARGET) test below.
+ADD_LIBRARY(ExeImportedTarget UNKNOWN IMPORTED)
+
+# Test if(TARGET) command.
+IF(NOT TARGET CMakeTestLibrary)
+  MESSAGE(FATAL_ERROR "IF(NOT TARGET CMakeTestLibrary) returned true!")
+ENDIF(NOT TARGET CMakeTestLibrary)
+IF(NOT TARGET ExeImportedTarget)
+  MESSAGE(FATAL_ERROR "IF(NOT TARGET ExeImportedTarget) returned true!")
+ENDIF(NOT TARGET ExeImportedTarget)
+IF(TARGET LibImportedTarget)
+  MESSAGE(FATAL_ERROR "IF(TARGET LibImportedTarget) returned true!")
+ENDIF(TARGET LibImportedTarget)
+IF(TARGET NotATarget)
+  MESSAGE(FATAL_ERROR "IF(TARGET NotATarget) returned true!")
+ENDIF(TARGET NotATarget)
+
   # Use LINK_LIBRARIES instead of TARGET_LINK_LIBRARIES to 
 SET(COMPLEX_LIBS CMakeTestLibrary;CMakeTestLibraryShared;CMakeTestCLibraryShared)
 LINK_LIBRARIES(${COMPLEX_LIBS})

Tests/ComplexRelativePaths/Library/CMakeLists.txt

@@ -114,6 +114,10 @@ INSTALL_FILES(/tmp .cxx ${Complex_BINARY_DIR}/cmTestConfigure.h)
 # Test creating a library that is not built by default.
 ADD_LIBRARY(notInAllLib EXCLUDE_FROM_ALL notInAllLib.cxx)
 
+# Create an imported target for if(TARGET) test in Executable dir.
+# That test should not see this target.
+ADD_LIBRARY(LibImportedTarget UNKNOWN IMPORTED)
+
 # Test generation of preprocessed sources.
 IF("${CMAKE_GENERATOR}" MATCHES "Makefile" AND CMAKE_MAKE_PROGRAM)
   IF(CMAKE_CXX_CREATE_PREPROCESSED_SOURCE)