When another part of (or another Emacs package using ) queries
the SemanticDB library for a source code tag, the search need not
be limited to tags defined within the current file. It can
include tags defined elsewhere, such as header files
referenced by the current file (e.g., via the C/C++
#include directive). While performing the search,
the SemanticDB library may even automatically visit other files
and parse them, if necessary.
The variable semanticdb-find-default-throttle
determines how aggressively SemanticDB searches for source code
tags. See Search
Throttle.
The details of SemanticDB searches can vary from language to
language. In C/C++ code, for example, SemanticDB distinguishes
between project header files and system header
files, based on whether the #include directive
uses the "" or <> filename
delimiter. SemanticDB looks for system header in the system
include path (see Include paths).