As most GNU Makefiles (or Makevars) tend to use '=' insead of ':=', I
thought it
might be helpful to point out that there is an important difference in the
meaning.
When a variable is defined like this:
PKG_CPPFLAGS=whatever
the RHS (whatever) is evaluated every time PKG_CPPFLAGS is used,
and this can have undesirable side-effects, especially when whatever
is a shell escape.
On the other hand, with
PKG_CPPFLAGS:=whatever
the assignment only happens once, and this is normally what
is expected to happen.
Thus it is probably better to use := in most cases.
Dominick
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