Incorrect header parsing with clang code model enabled

Simple qbs project (see attached files), clang code model enabled. Namespace declaration in header files in underlined with red, hovering a cursor on it shows "unknown type name 'namespace'". Running Creator as "LANG=en_US.UTF-8 QTC_CLANG_VERBOSE=1 ./qtcreator.sh" gives the following errors:

error: invalid argument '-std=gnu89' not allowed with 'C+/ObjC+'
/home/mbalabin/qbs-test-project/foo.h:1:1: error: unknown type name 'namespace'
/home/mbalabin/qbs-test-project/foo.h:1:14: error: expected ';' after top level declarator

Complete log is attached as a file.