Merge branch 'backport-cmake-warn-no-src-build-dir' into release-3.13

Merge-request: !2839

Help/release/3.13.rst

@@ -252,3 +252,29 @@ Changes made since CMake 3.13.0 include the following.
   directories to the ``moc`` tool for :prop_tgt:`AUTOMOC`.  This has
   been reverted due to regressing existing builds and will need
   further investigation before being re-introduced in a later release.
+
+3.13.3
+------
+
+* The :generator:`Visual Studio 15 2017` generator has been fixed to work
+  when VS 2019 is installed.
+
+* CMake now checks that at least one of the source or binary directory
+  is specified when running CMake and issues an error if both are missing.
+  This has always been a documented requirement, but the implementation
+  previously accidentally accepted cases in which neither are specified
+  so long as some other argument is given, and silently used the current
+  working directory as the source and build tree.
+
+3.13.4
+------
+
+* The error added by 3.13.3 in cases that neither a source or binary
+  directory is specified has been downgraded to a warning.  While this
+  was never intended, documented, nor supported behavior, some projects
+  relied on it.  The error has been downgraded to a warning for the
+  remainder of the 3.13.x release series to allow a transition period,
+  but it may become a fatal error again in a later release.  Scripts
+  relying on the old behavior can be trivially fixed by specifying
+  the path to the source tree (even if just ``.``) explicitly and
+  continue to work with all versions of CMake.

Source/cmake.cxx

@@ -808,8 +808,11 @@ void cmake::SetArgs(const std::vector<std::string>& args)
 
   if (this->CurrentWorkingMode == cmake::NORMAL_MODE && !haveSourceDir &&
       !haveBinaryDir) {
-    cmSystemTools::Error("No source or binary directory provided");
-    return;
+    this->IssueMessage(
+      cmake::WARNING,
+      "No source or binary directory provided. Both will be assumed to be "
+      "the same as the current working directory, but note that this "
+      "warning will become a fatal error in future CMake releases.");
   }
 
   if (!haveSourceDir) {

Tests/RunCMake/CommandLine/RunCMakeTest.cmake

@@ -54,12 +54,22 @@ run_cmake_command(cache-empty-entry
   ${CMAKE_COMMAND} --build ${RunCMake_SOURCE_DIR}/cache-empty-entry/)
 
 function(run_ExplicitDirs)
+  set(source_dir ${RunCMake_BINARY_DIR}/ExplicitDirsMissing)
+
+  file(REMOVE_RECURSE "${source_dir}")
+  file(MAKE_DIRECTORY "${source_dir}")
+  file(WRITE ${source_dir}/CMakeLists.txt [=[
+cmake_minimum_required(VERSION 3.13)
+project(ExplicitDirsMissing LANGUAGES NONE)
+]=])
+  run_cmake_command(no-S-B ${CMAKE_COMMAND} -E chdir ${source_dir}
+    ${CMAKE_COMMAND} -DFOO=BAR)
+
   set(source_dir ${RunCMake_SOURCE_DIR}/ExplicitDirs)
   set(binary_dir ${RunCMake_BINARY_DIR}/ExplicitDirs-build)
 
   file(REMOVE_RECURSE "${binary_dir}")
   file(MAKE_DIRECTORY "${binary_dir}")
-  run_cmake_command(no-S-B ${CMAKE_COMMAND} -DFOO=BAR)
   run_cmake_command(S-arg ${CMAKE_COMMAND} -S ${source_dir} ${binary_dir})
   run_cmake_command(S-arg-reverse-order ${CMAKE_COMMAND} ${binary_dir} -S${source_dir} )
   run_cmake_command(S-no-arg ${CMAKE_COMMAND} -S )

Tests/RunCMake/CommandLine/no-S-B-result.txt

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

Tests/RunCMake/CommandLine/no-S-B-stderr.txt

@@ -1 +1,4 @@
-CMake Error: No source or binary directory provided
+CMake Warning:
+  No source or binary directory provided.  Both will be assumed to be the
+  same as the current working directory, but note that this warning will
+  become a fatal error in future CMake releases.