Fix qdoc call after it moved to LLVM/Clang

For some unknown reason qdoc does not add the include paths for
Qt modules, so we need to do that manually.
Also, if we do that, we need to pass it the default include paths, so
standard C++ headers are found.

Qt includes and standard headers are found now, but

Framework style includes on macOS still fail ("QtCore/QString"), which are
used in Qt headers as well. Looks like the framework path that is passed
with -F to qdoc is not passed on correctly.

Task-number: QTCREATORBUG-22451
Change-Id: I04b2c75ecdeb1f0e70ba9adfea039f0ff16ec96b
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

doc/config/qt-defines.qdocconf

@@ -9,7 +9,6 @@ defines                 = Q_QDOC \
                           Q_OS_.* \
                           Q_BYTE_ORDER \
 			  QT_DEPRECATED \
-                          Q_NO_USING_KEYWORD \
-                          __cplusplus
+                          Q_NO_USING_KEYWORD
 
 versionsym              = QT_VERSION_STR

doc/doc_targets.pri

@@ -41,7 +41,7 @@ for (doc_file, DOC_FILES) {
     DOC_TARGETDIR = $$DOC_TARGET
     DOC_OUTPUTDIR = $${DOCS_BASE_OUTDIR}/$${DOC_TARGETDIR}$${DOC_OUTDIR_POSTFIX}
 
-    html_docs_$${DOC_TARGET}.commands = $$QDOC -outputdir $$shell_quote($$DOC_OUTPUTDIR) $$doc_file $$DOC_INDEXES
+    html_docs_$${DOC_TARGET}.commands = $$QDOC -outputdir $$shell_quote($$DOC_OUTPUTDIR) $$doc_file $$DOC_INDEXES $$DOC_INCLUDES
     QMAKE_EXTRA_TARGETS += html_docs_$${DOC_TARGET}
 
     !isEmpty(html_docs.commands): html_docs.commands += &&

docs.pri

@@ -41,4 +41,17 @@ DOC_HTML_INSTALLDIR = $$INSTALL_DOC_PATH
 DOC_QCH_OUTDIR = $$IDE_DOC_PATH
 DOC_QCH_INSTALLDIR = $$INSTALL_DOC_PATH
 
+minQtVersion(5, 11, 0) {
+    for (include_path, INCLUDEPATH): \
+        DOC_INCLUDES += -I $$shell_quote($$include_path)
+    for (module, QT) {
+        MOD_INCLUDES = $$eval(QT.$${module}.includes)
+        for (include_path, MOD_INCLUDES): \
+            DOC_INCLUDES += -I $$shell_quote($$include_path)
+    }
+    for (include_path, QMAKE_DEFAULT_INCDIRS): \
+        DOC_INCLUDES += -I $$shell_quote($$include_path)
+    macos: DOC_INCLUDES += -F $$shell_quote($$[QT_INSTALL_LIBS])
+}
+
 include(doc/doc_targets.pri)