Heads up: `lexlib` was moved into the `lexilla` source tree, so that last include statement does nothing.

Try including `scintilla/src` instead: ```diff diff --git a/scintilla/Makefile.am b/scintilla/Makefile.am index 4fe3851c0..543b7a4d6 100644 --- a/scintilla/Makefile.am +++ b/scintilla/Makefile.am @@ -175,7 +175,7 @@ liblexilla_la_CPPFLAGS += -I$(srcdir)/lexilla/include -I$(srcdir)/lexilla/lexlib liblexilla_la_SOURCES = $(LEXLIB_SRCS) $(LEXER_SRCS)

libscintilla_la_CPPFLAGS = $(AM_CPPFLAGS) -libscintilla_la_CPPFLAGS += -I$(top_srcdir) -I$(srcdir)/include -I$(srcdir)/lexlib +libscintilla_la_CPPFLAGS += -I$(top_srcdir) -I$(srcdir)/include -I$(srcdir)/src libscintilla_la_SOURCES = $(SRCS)

marshallers: gtk/scintilla-marshal.list ``` That might resolve your [header resolution problem](https://app.travis-ci.com/github/geany/geany/jobs/532735207#L1222): ``` make[2]: Leaving directory '/home/travis/build/geany/geany/_build/ctags' Making all in scintilla make[2]: Entering directory '/home/travis/build/geany/geany/_build/scintilla' CXX gtk/libscintilla_la-PlatGTK.lo CXX gtk/libscintilla_la-ScintillaGTK.lo ../../scintilla/gtk/PlatGTK.cxx:30:10: fatal error: Debugging.h: No such file or directory #include "Debugging.h" ^~~~~~~~~~~~~ ```