get_target_property: Error on non-existent target.

Introduce policy CMP0045 to control this behavior.

Help/manual/cmake-policies.7.rst

@@ -94,3 +94,4 @@ All Policies
    /policy/CMP0042
    /policy/CMP0043
    /policy/CMP0044
+   /policy/CMP0045

Help/policy/CMP0045.rst

+CMP0045
+-------
+
+Error on non-existent target in get_target_property.
+
+In CMake 2.8.12 and lower, the :command:`get_target_property` command accepted
+a non-existent target argument without issuing any error or warning.  The
+result variable is set to a ``-NOTFOUND`` value.
+
+The OLD behavior for this policy is to issue no warning and set the result
+variable to a ``-NOTFOUND`` value.  The NEW behavior
+for this policy is to issue a ``FATAL_ERROR`` if the command is called with a
+non-existent target.
+
+This policy was introduced in CMake version 3.0.0.  CMake version
+|release| warns when the policy is not set and uses OLD behavior.  Use
+the cmake_policy command to set it to OLD or NEW explicitly.

Source/cmGetTargetPropertyCommand.cxx

@@ -40,7 +40,36 @@ bool cmGetTargetPropertyCommand
     cmTarget& target = *tgt;
     prop = target.GetProperty(args[2].c_str());
     }
-
+  else
+    {
+    bool issueMessage = false;
+    cmOStringStream e;
+    cmake::MessageType messageType = cmake::AUTHOR_WARNING;
+    switch(this->Makefile->GetPolicyStatus(cmPolicies::CMP0045))
+      {
+      case cmPolicies::WARN:
+        issueMessage = true;
+        e << this->Makefile->GetPolicies()
+                          ->GetPolicyWarning(cmPolicies::CMP0045) << "\n";
+      case cmPolicies::OLD:
+        break;
+      case cmPolicies::REQUIRED_IF_USED:
+      case cmPolicies::REQUIRED_ALWAYS:
+      case cmPolicies::NEW:
+        issueMessage = true;
+        messageType = cmake::FATAL_ERROR;
+      }
+    if (issueMessage)
+      {
+      e << "get_target_property() called with non-existent target \""
+        << targetName <<  "\".";
+      this->Makefile->IssueMessage(messageType, e.str().c_str());
+      if (messageType == cmake::FATAL_ERROR)
+        {
+        return false;
+        }
+      }
+    }
   if (prop)
     {
     this->Makefile->AddDefinition(var.c_str(), prop);

Source/cmPolicies.cxx

@@ -326,6 +326,11 @@ cmPolicies::cmPolicies()
     CMP0044, "CMP0044",
     "Case sensitive <LANG>_COMPILER_ID generator expressions.",
     3,0,0,0, cmPolicies::WARN);
+
+  this->DefinePolicy(
+    CMP0045, "CMP0045",
+    "Error on non-existent target in get_target_property.",
+    3,0,0,0, cmPolicies::WARN);
 }
 
 cmPolicies::~cmPolicies()

Source/cmPolicies.h

@@ -98,6 +98,7 @@ public:
     CMP0042, ///< Enable MACOSX_RPATH by default
     CMP0043, ///< Ignore COMPILE_DEFINITIONS_<Config> properties
     CMP0044, ///< Case sensitive <LANG>_COMPILER_ID generator expressions
+    CMP0045, ///< Error on non-existent target in get_target_property
 
     /** \brief Always the last entry.
      *

Tests/RunCMake/CMP0045/CMP0045-NEW-result.txt

+1

Tests/RunCMake/CMP0045/CMP0045-NEW-stderr.txt

+CMake Error at CMP0045-NEW.cmake:4 \(get_target_property\):
+  get_target_property\(\) called with non-existent target "tgt".
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)

Tests/RunCMake/CMP0045/CMP0045-NEW.cmake

+
+cmake_policy(SET CMP0045 NEW)
+
+get_target_property(result tgt TYPE)

Tests/RunCMake/CMP0045/CMP0045-OLD-result.txt

+0

Tests/RunCMake/CMP0045/CMP0045-OLD-stderr.txt

+^$

Tests/RunCMake/CMP0045/CMP0045-OLD.cmake

+
+cmake_policy(SET CMP0045 OLD)
+
+get_target_property(result tgt TYPE)

Tests/RunCMake/CMP0045/CMP0045-WARN-result.txt

+0

Tests/RunCMake/CMP0045/CMP0045-WARN-stderr.txt

+CMake Warning \(dev\) at CMP0045-WARN.cmake:2 \(get_target_property\):
+  Policy CMP0045 is not set: Error on non-existent target in
+  get_target_property.  Run "cmake --help-policy CMP0045" for policy details.
+  Use the cmake_policy command to set the policy and suppress this warning.
+
+  get_target_property\(\) called with non-existent target "tgt".
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
+This warning is for project developers.  Use -Wno-dev to suppress it.

Tests/RunCMake/CMP0045/CMP0045-WARN.cmake

+
+get_target_property(result tgt TYPE)

Tests/RunCMake/CMP0045/CMakeLists.txt

+cmake_minimum_required(VERSION 2.8)
+project(${RunCMake_TEST} CXX)
+include(${RunCMake_TEST}.cmake NO_POLICY_SCOPE)

Tests/RunCMake/CMP0045/RunCMakeTest.cmake

+include(RunCMake)
+
+run_cmake(CMP0045-OLD)
+run_cmake(CMP0045-NEW)
+run_cmake(CMP0045-WARN)

Tests/RunCMake/CMP0045/empty.cpp

+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int empty()
+{
+  return 0;
+}

Tests/RunCMake/CMakeLists.txt

@@ -65,6 +65,7 @@ if(CMAKE_SYSTEM_NAME MATCHES Darwin AND CMAKE_SHARED_LIBRARY_RUNTIME_C_FLAG)
   add_RunCMake_test(CMP0042)
 endif()
 add_RunCMake_test(CMP0043)
+add_RunCMake_test(CMP0045)
 add_RunCMake_test(CTest)
 if(UNIX AND "${CMAKE_TEST_GENERATOR}" MATCHES "Unix Makefiles")
   add_RunCMake_test(CompilerChange)