add_custom_command: Disallow use of SOURCE signatures.

Add CMP0050 to control this behavior.

Help/manual/cmake-policies.7.rst

@@ -101,3 +101,4 @@ All Policies
    /policy/CMP0047
    /policy/CMP0048
    /policy/CMP0049
+   /policy/CMP0050

Help/policy/CMP0050.rst

+CMP0050
+-------
+
+Disallow add_custom_command SOURCE signatures.
+
+CMake 2.8.12 and lower allowed a signature for :command:`add_custom_command`
+which specified an input to a command.  This was undocumented behavior.
+Modern use of CMake associates custom commands with their output, rather
+than their input.
+
+The OLD behavior for this policy is to allow the use of
+:command:`add_custom_command` SOURCE signatures.  The NEW behavior for this
+policy is to issue an error if such a signature is used.
+
+This policy was introduced in CMake version 3.0.
+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.

Help/release/3.0.rst

@@ -327,6 +327,9 @@ New Diagnostics
   require an undocumented extra layer of variable expansion.
   See policy :policy:`CMP0049`.
 
+* Use of :command:`add_custom_command` undocumented ``SOURCE``
+  signatures now results in an error.  See policy :policy:`CMP0050`.
+
 Deprecated and Removed Features
 ===============================
 

Source/cmAddCustomCommandCommand.cxx

@@ -344,6 +344,36 @@ bool cmAddCustomCommandCommand
     }
   else
     {
+    bool issueMessage = true;
+    cmOStringStream e;
+    cmake::MessageType messageType = cmake::AUTHOR_WARNING;
+    switch(this->Makefile->GetPolicyStatus(cmPolicies::CMP0050))
+    {
+    case cmPolicies::WARN:
+      e << (this->Makefile->GetPolicies()
+                ->GetPolicyWarning(cmPolicies::CMP0050)) << "\n";
+      break;
+    case cmPolicies::OLD:
+      issueMessage = false;
+      break;
+    case cmPolicies::REQUIRED_ALWAYS:
+    case cmPolicies::REQUIRED_IF_USED:
+    case cmPolicies::NEW:
+      messageType = cmake::FATAL_ERROR;
+      break;
+    }
+
+    if (issueMessage)
+      {
+      e << "The SOURCE signatures of add_custom_command are no longer "
+           "supported.";
+      this->Makefile->IssueMessage(messageType, e.str().c_str());
+      if (messageType == cmake::FATAL_ERROR)
+        {
+        return false;
+        }
+      }
+
     // Use the old-style mode for backward compatibility.
     this->Makefile->AddCustomCommandOldStyle(target.c_str(), outputs, depends,
                                              source.c_str(), commandLines,

Source/cmPolicies.cxx

@@ -338,6 +338,11 @@ cmPolicies::cmPolicies()
     CMP0049, "CMP0049",
     "Do not expand variables in target source entries.",
     3,0,0, cmPolicies::WARN);
+
+  this->DefinePolicy(
+    CMP0050, "CMP0050",
+    "Disallow add_custom_command SOURCE signatures.",
+    3,0,0, cmPolicies::WARN);
 }
 
 cmPolicies::~cmPolicies()

Source/cmPolicies.h

@@ -103,6 +103,7 @@ public:
     CMP0047, ///< Use QCC compiler id for the qcc drivers on QNX.
     CMP0048, ///< project() command manages VERSION variables
     CMP0049, ///< Do not expand variables in target source entries
+    CMP0050, ///< Disallow add_custom_command SOURCE signatures
 
     /** \brief Always the last entry.
      *

Tests/RunCMake/CMP0050/CMP0050-NEW-result.txt

+1

Tests/RunCMake/CMP0050/CMP0050-NEW-stderr.txt

+CMake Error at CMP0050-NEW.cmake:5 \(add_custom_command\):
+  The SOURCE signatures of add_custom_command are no longer supported.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)

Tests/RunCMake/CMP0050/CMP0050-NEW.cmake

+
+cmake_policy(SET CMP0050 NEW)
+
+add_library(empty empty.cpp)
+add_custom_command(
+  TARGET empty
+  SOURCE ${CMAKE_CURRENT_SOURCE_DIR}/input.h.in
+  COMMAND ${CMAKE_COMMAND}
+  ARGS -E copy ${CMAKE_CURRENT_SOURCE_DIR}/input.h.in
+               ${CMAKE_CURRENT_BINARY_DIR}/input.h
+  OUTPUTS ${CMAKE_CURRENT_BINARY_DIR}/input.h
+  DEPENDS ${CMAKE_COMMAND}
+)

Tests/RunCMake/CMP0050/CMP0050-OLD-result.txt

+0

Tests/RunCMake/CMP0050/CMP0050-OLD-stderr.txt

+^$

Tests/RunCMake/CMP0050/CMP0050-OLD.cmake

+
+cmake_policy(SET CMP0050 OLD)
+
+add_library(empty empty.cpp)
+add_custom_command(
+  TARGET empty
+  SOURCE ${CMAKE_CURRENT_SOURCE_DIR}/input.h.in
+  COMMAND ${CMAKE_COMMAND}
+  ARGS -E copy ${CMAKE_CURRENT_SOURCE_DIR}/input.h.in
+               ${CMAKE_CURRENT_BINARY_DIR}/input.h
+  OUTPUTS ${CMAKE_CURRENT_BINARY_DIR}/input.h
+  DEPENDS ${CMAKE_COMMAND}
+)

Tests/RunCMake/CMP0050/CMP0050-WARN-result.txt

+0

Tests/RunCMake/CMP0050/CMP0050-WARN-stderr.txt

+CMake Warning \(dev\) at CMP0050-WARN.cmake:3 \(add_custom_command\):
+  Policy CMP0050 is not set: Disallow add_custom_command SOURCE signatures.
+  Run "cmake --help-policy CMP0050" for policy details.  Use the cmake_policy
+  command to set the policy and suppress this warning.
+
+  The SOURCE signatures of add_custom_command are no longer supported.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
+This warning is for project developers.  Use -Wno-dev to suppress it.

Tests/RunCMake/CMP0050/CMP0050-WARN.cmake

+
+add_library(empty empty.cpp)
+add_custom_command(
+  TARGET empty
+  SOURCE ${CMAKE_CURRENT_SOURCE_DIR}/input.h.in
+  COMMAND ${CMAKE_COMMAND}
+  ARGS -E copy ${CMAKE_CURRENT_SOURCE_DIR}/input.h.in
+               ${CMAKE_CURRENT_BINARY_DIR}/input.h
+  OUTPUTS ${CMAKE_CURRENT_BINARY_DIR}/input.h
+  DEPENDS ${CMAKE_COMMAND}
+)

Tests/RunCMake/CMP0050/CMakeLists.txt

+cmake_minimum_required(VERSION 2.8.12)
+project(${RunCMake_TEST} CXX)
+include(${RunCMake_TEST}.cmake NO_POLICY_SCOPE)

Tests/RunCMake/CMP0050/RunCMakeTest.cmake

+include(RunCMake)
+
+run_cmake(CMP0050-OLD)
+run_cmake(CMP0050-NEW)
+run_cmake(CMP0050-WARN)

Tests/RunCMake/CMP0050/empty.cpp

+
+#include "input.h"
+
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int empty()
+{
+  return 0;
+}

Tests/RunCMake/CMP0050/input.h.in

+
+#define INPUT

Tests/RunCMake/CMakeLists.txt

@@ -33,6 +33,7 @@ add_RunCMake_test(CMP0043)
 add_RunCMake_test(CMP0045)
 add_RunCMake_test(CMP0046)
 add_RunCMake_test(CMP0049)
+add_RunCMake_test(CMP0050)
 add_RunCMake_test(CTest)
 if(UNIX AND "${CMAKE_TEST_GENERATOR}" MATCHES "Unix Makefiles")
   add_RunCMake_test(CompilerChange)