If we are trying to store an empty sentinel value for a
make-var, we would consider a missing file the same as an
empty variable. E.g., repeatedly running:


will not create MAKE/USER-AGENT at all if it does not exist,
and subsequent make invocations will force a rebuild. This
is not generally a problem in practice, since most of the
files always have some boilerplate (even LDFLAGS, because it
is formed with "+=", will have a stray space in it). But
this does fix the rare case, and future-proofs us as we add
more similar variables.

Signed-off-by: Jeff King <p...@peff.net>
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 7fecdf1..e12039f 100644
--- a/Makefile
+++ b/Makefile
@@ -1569,7 +1569,7 @@ endif
 define make-var
        @VALUE='$$(subst ','\'',$3)'; \
-       if test x"$$$$VALUE" != x"`cat $$@ 2>/dev/null`"; then \
+       if ! test -e $$@ || test x"$$$$VALUE" != x"`cat $$@`"; then \
                echo >&2 "    * new $2"; \
                printf '%s\n' "$$$$VALUE" >$$@+ && \
                mv $$@+ $$@; \

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