cmLocalGenerator: Extend the functionality of ``GetIncludeDirectories()``

What ``cmLocalGenerator::GetIncludeDirectories`` does
-----------------------------------------------------

In general it concatenates the

1. ``target->GetIncludeDirectories(LANG)`` and the
2. ``CMAKE_<LANG>_STANDARD_INCLUDE_DIRECTORIES``.

Additionally it performs some sorting and special treatment of the

- ``CMAKE_<LANG>_IMPLICIT_INCLUDE_DIRECTORIES``.

By default all ``CMAKE_<LANG>_IMPLICIT_INCLUDE_DIRECTORIES`` are stripped from
the result list.

When explicitly requested (by setting ``stripImplicitInclDirs=false``) *some*
implicit directories are appended to the result list.  The implicit directories
that *are* appended are those that were requested to be included by

1. ``target->GetIncludeDirectories(LANG)`` or
2. ``CMAKE_<LANG>_STANDARD_INCLUDE_DIRECTORIES``.

All other implicit directories are still stripped from the result list.

The reason to not simply append all implicit directories is that Qt4's moc has
problems to parse some headers that might be found in the implicit system
include directories (See commit d2536579d51e77827b8e55f39123316324314781
and
[QTBUG-28045](https://bugreports.qt.io/browse/QTBUG-28045)
).
That has been solved in Qt5's moc though.

Extension request to ``cmLocalGenerator::GetIncludeDirectories``
----------------------------------------------------------------

For Qt5's moc we like to have an option that allows to append *all* implict
include directories to the result list, not just those that were user requested.

Changes to ``cmLocalGenerator::GetIncludeDirectories``
------------------------------------------------------

- Shorten the function parameter name ``stripImplicitInclDirs`` to
  ``stripImplicitDirs``.

- Add new boolean function parameter ``appendAllImplicitDirs``
  with a default value ``false``.

The old default behavior of the function stays the same, but a specialized
behavior can be requested by AUTOMOC for Qt4/Qt5 respectively.

2 files changed, 30 insertions, 11 deletions

diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index 3df701e..647697a 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -844,7 +844,8 @@ void cmLocalGenerator::GetIncludeDirectories(std::vector<std::string>& dirs,
                                              cmGeneratorTarget const* target,
                                              const std::string& lang,
                                              const std::string& config,
-                                             bool stripImplicitInclDirs) const
+                                             bool stripImplicitDirs,
+                                             bool appendAllImplicitDirs) const
 {
   // Do not repeat an include path.
   std::set<std::string> emitted;
@@ -898,12 +899,12 @@ void cmLocalGenerator::GetIncludeDirectories(std::vector<std::string>& dirs,
       std::vector<std::string> impDirVec;
       cmSystemTools::ExpandListArgument(value, impDirVec);
       for (std::string const& i : impDirVec) {
-        std::string d = rootPath + i;
-        cmSystemTools::ConvertToUnixSlashes(d);
-        emitted.insert(std::move(d));
-        if (!stripImplicitInclDirs) {
-          implicitDirs.push_back(i);
+        {
+          std::string d = rootPath + i;
+          cmSystemTools::ConvertToUnixSlashes(d);
+          emitted.insert(std::move(d));
         }
+        implicitDirs.push_back(i);
       }
     }
   }
@@ -958,9 +959,21 @@ void cmLocalGenerator::GetIncludeDirectories(std::vector<std::string>& dirs,
     }
   }
 
-  for (std::string const& i : implicitDirs) {
-    if (std::find(userDirs.begin(), userDirs.end(), i) != userDirs.end()) {
-      dirs.push_back(i);
+  if (!stripImplicitDirs) {
+    if (!appendAllImplicitDirs) {
+      // Append only those implicit directories that were requested by the user
+      for (std::string const& i : implicitDirs) {
+        if (std::find(userDirs.begin(), userDirs.end(), i) != userDirs.end()) {
+          dirs.push_back(i);
+        }
+      }
+    } else {
+      // Append all implicit directories
+      for (std::string const& i : implicitDirs) {
+        if (std::find(dirs.begin(), dirs.end(), i) == dirs.end()) {
+          dirs.push_back(i);
+        }
+      }
     }
   }
 }
diff --git a/Source/cmLocalGenerator.h b/Source/cmLocalGenerator.h
index 9ba62cc..52f0396 100644
--- a/Source/cmLocalGenerator.h
+++ b/Source/cmLocalGenerator.h
@@ -237,12 +237,18 @@ public:
     return true;
   }
 
-  /** Get the include flags for the current makefile and language.  */
+  /** @brief Get the include directories for the current makefile and language.
+   * @arg stripImplicitDirs Strip all directories found in
+   *      CMAKE_<LANG>_IMPLICIT_INCLUDE_DIRECTORIES from the result.
+   * @arg appendAllImplicitDirs Append all directories found in
+   *      CMAKE_<LANG>_IMPLICIT_INCLUDE_DIRECTORIES to the result.
+   */
   void GetIncludeDirectories(std::vector<std::string>& dirs,
                              cmGeneratorTarget const* target,
                              const std::string& lang = "C",
                              const std::string& config = "",
-                             bool stripImplicitInclDirs = true) const;
+                             bool stripImplicitDirs = true,
+                             bool appendAllImplicitDirs = false) const;
   void AddCompileOptions(std::string& flags, cmGeneratorTarget* target,
                          const std::string& lang, const std::string& config);
   void AddCompileDefinitions(std::set<std::string>& defines,