CMakePM: Treat header files as project files

CMake doesn't associate header files in a compiler group in the
file-api export. But it does list them as source files if added
to the source files of a target.

By using the CppEditor::ProjectFileCategorizer we can sort the
header files to the right compiler group.

This way one could have the clang-tidy and clazy run on a header
file. Or the TODO plugin find TODOs in header files. Or the Autotest
plugin finding Google Tests in header files.

Fixes: QTCREATORBUG-23783
Fixes: QTCREATORBUG-23843
Fixes: QTCREATORBUG-26201
Fixes: QTCREATORBUG-26238
Change-Id: I8acace48e89fd9b3da8bce1c479dec7891e1bbd4
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/cmakeprojectmanager/fileapidataextractor.cpp

@@ -28,6 +28,8 @@
 #include "fileapiparser.h"
 #include "projecttreehelper.h"
 
+#include <cppeditor/cppprojectfilecategorizer.h>
+
 #include <utils/algorithm.h>
 #include <utils/qtcassert.h>
 #include <utils/qtcprocess.h>
@@ -329,6 +331,11 @@ RawProjectParts generateRawProjectParts(const PreprocessedData &input,
     for (const TargetDetails &t : input.targetDetails) {
         QDir sourceDir(sourceDirectory.toString());
 
+        CppEditor::ProjectFileCategorizer
+            categorizer({}, transform<QList>(t.sources, [&sourceDir](const SourceInfo &si) {
+                            return sourceDir.absoluteFilePath(si.path);
+                        }));
+
         bool needPostfix = t.compileGroups.size() > 1;
         int count = 1;
         for (const CompileInfo &ci : t.compileGroups) {
@@ -375,8 +382,14 @@ RawProjectParts generateRawProjectParts(const PreprocessedData &input,
                                            return si.path.endsWith(ending);
                                        }).path);
 
-            rpp.setFiles(transform<QList>(ci.sources, [&t, &sourceDir](const int si) {
+            CppEditor::ProjectFiles sources;
-                return sourceDir.absoluteFilePath(t.sources[static_cast<size_t>(si)].path);
+            if (ci.language == "C")
+                sources = categorizer.cSources();
+            else if (ci.language == "CXX")
+                sources = categorizer.cxxSources();
+
+            rpp.setFiles(transform<QList>(sources, [](const CppEditor::ProjectFile &pf) {
+                return pf.path;
             }));
             if (!precompiled_header.isEmpty()) {
                 if (precompiled_header.toFileInfo().isRelative()) {

src/plugins/cppeditor/cppprojectfilecategorizer.h

@@ -34,7 +34,7 @@
 
 namespace CppEditor {
 
-class ProjectFileCategorizer
+class CPPEDITOR_EXPORT ProjectFileCategorizer
 {
 public:
     using FileIsActive = ProjectExplorer::RawProjectPart::FileIsActive;