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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/make.texi | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/doc/make.texi b/doc/make.texi index 943c0941..085e9c24 100644 --- a/doc/make.texi +++ b/doc/make.texi @@ -8616,6 +8616,23 @@ using a very strange shell, this has the same result as @w{@samp{$(wildcard *.c)}} (as long as at least one @samp{.c} file exists).@refill +All variables that are marked as @code{export} will also be passed to the +shell started by the @code{shell} function. It is possible to create a +variable expansion loop: consider this @file{makefile}: + +@example +export HI = $(shell echo hi) +all: ; @@echo $$HI +@end example + +When @code{make} wants to run the recipe it must add the variable @var{HI} to +the environment; to do so it must be expanded. The value of this variable +requires an invocation of the @code{shell} function, and to invoke it we must +create its environment. Since @var{HI} is exported, we need to expand it to +create its environment. And so on. In this obscure case @code{make} will not +add recursively-expanded variables to the @code{shell} environment rather than +fail with an error. + @node Guile Function, , Shell Function, Functions @section The @code{guile} Function @findex guile |