autoconf: VPATH and Make

1 
1 12.18 `VPATH' and Make
1 ======================
1 
1 Posix does not specify the semantics of `VPATH'.  Typically, `make'
1 supports `VPATH', but its implementation is not consistent.
1 
1    Autoconf and Automake support makefiles whose usages of `VPATH' are
1 portable to recent-enough popular implementations of `make', but to
1 keep the resulting makefiles portable, a package's makefile prototypes
1 must take the following issues into account.  These issues are
1 complicated and are often poorly understood, and installers who use
1 `VPATH' should expect to find many bugs in this area.  If you use
1 `VPATH', the simplest way to avoid these portability bugs is to stick
1 with GNU `make', since it is the most commonly-used `make' among
1 Autoconf users.
1 
1    Here are some known issues with some `VPATH' implementations.
1 

Menu

1 
· Variables listed in VPATH   `VPATH' must be literal on ancient hosts
· VPATH and Double-colon      Problems with `::' on ancient hosts
· $< in Explicit Rules        `$<' does not work in ordinary rules
· Automatic Rule Rewriting    `VPATH' goes wild on Solaris
· Tru64 Directory Magic       `mkdir' goes wild on Tru64
· Make Target Lookup          More details about `VPATH' lookup
1