Handle relative WORKING_DIRECTORY in add_custom_(command|target)

This also fixes handling of trailing slashes in the directory name.

Source/cmAddCustomCommandCommand.cxx

@@ -286,6 +286,13 @@ bool cmAddCustomCommandCommand
     return false;
     }
 
+  // Convert working directory to a full path.
+  if(!working.empty())
+    {
+    const char* build_dir = this->Makefile->GetCurrentOutputDirectory();
+    working = cmSystemTools::CollapseFullPath(working.c_str(), build_dir);
+    }
+
   // Choose which mode of the command to use.
   bool escapeOldStyle = !verbatim;
   if(source.empty() && output.empty())

Source/cmAddCustomCommandCommand.h

@@ -110,6 +110,8 @@ public:
       "will be treated as PRE_LINK.\n"
       "If WORKING_DIRECTORY is specified the command will be executed "
       "in the directory given. "
+      "If it is a relative path it will be interpreted relative to the "
+      "build tree directory corresponding to the current source directory. "
       "If COMMENT is set, the value will be displayed as a "
       "message before the commands are executed at build time. "
       "If APPEND is specified the COMMAND and DEPENDS option values "

Source/cmAddCustomTargetCommand.cxx

@@ -166,6 +166,14 @@ bool cmAddCustomTargetCommand
     }
   }
 
+  // Convert working directory to a full path.
+  if(!working_directory.empty())
+    {
+    const char* build_dir = this->Makefile->GetCurrentOutputDirectory();
+    working_directory =
+      cmSystemTools::CollapseFullPath(working_directory.c_str(), build_dir);
+    }
+
   // Add the utility target to the makefile.
   bool escapeOldStyle = !verbatim;
   cmTarget* target =

Source/cmAddCustomTargetCommand.h

@@ -79,6 +79,8 @@ public:
       "empty target will be created. "
       "If WORKING_DIRECTORY is set, then the command will be run in that "
       "directory. "
+      "If it is a relative path it will be interpreted relative to the "
+      "build tree directory corresponding to the current source directory. "
       "If COMMENT is set, the value will be displayed as a "
       "message before the commands are executed at build time. "
       "Dependencies listed with the DEPENDS argument may reference files "

Tests/CustomCommandWorkingDirectory/CMakeLists.txt

@@ -10,6 +10,7 @@ ADD_CUSTOM_COMMAND(
 
 SET_SOURCE_FILES_PROPERTIES(
   "${TestWorkingDir_BINARY_DIR}/customTarget.c"
+  "${TestWorkingDir_BINARY_DIR}/customTarget2.c"
   PROPERTIES GENERATED 1)
 
 ADD_EXECUTABLE(working "${TestWorkingDir_BINARY_DIR}/working.c" 
@@ -28,8 +29,14 @@ add_custom_command(
   OUTPUT working2.c # Relative to build tree
   COMMAND "${CMAKE_COMMAND}" -E copy ${TestWorkingDir_SOURCE_DIR}/working.c.in ../working2.c
   DEPENDS ${TestWorkingDir_SOURCE_DIR}/working.c.in/ # trailing slash should be removed
-  WORKING_DIRECTORY ${TestWorkingDir_BINARY_DIR}/work
+  WORKING_DIRECTORY work/ # Relative to build tree, trailing slash
   )
-add_executable(working2 working2.c ${TestWorkingDir_BINARY_DIR}/customTarget.c)
+add_executable(working2 working2.c ${TestWorkingDir_BINARY_DIR}/customTarget2.c)
+
+add_custom_target(
+  Custom2 ALL
+  COMMAND "${CMAKE_COMMAND}" -E copy_if_different ${TestWorkingDir_SOURCE_DIR}/customTarget.c ../customTarget2.c
+  WORKING_DIRECTORY work/ # Relative to build tree, trailing slash
+)
 
 add_dependencies(working2 Custom2)