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Chapter 14: Incompatibilities and Missing Features 147

14 Incompatibilities and Missing Features

The make programs in various other systems support a few features that are not implemented

in GNU make. The POSIX.2 standard (IEEE Standard 1003.2-1992) which speciﬁes make

does not require any of these features.

• A target of the form ‘file((entry))’ stands for a member of archive ﬁle ﬁle. The

member is chosen, not by name, but by being an object ﬁle which deﬁnes the linker

symbol entry.

This feature was not put into GNU make because of the non-modularity of putting

knowledge into make of the internal format of archive ﬁle symbol tables. See

Section 11.2.1 [Updating Archive Symbol Directories], page 130.

• Suﬃxes (used in suﬃx rules) that end with the character ‘~’ have a special meaning to

System V make; they refer to the SCCS ﬁle that corresponds to the ﬁle one would get

without the ‘~’. For example, the suﬃx rule ‘.c~.o’ would make the ﬁle n.o from the

SCCS ﬁle s.n.c. For complete coverage, a whole series of such suﬃx rules is required.

See Section 10.7 [Old-Fashioned Suﬃx Rules], page 125.

In GNU make, this entire series of cases is handled by two pattern rules for extraction

from SCCS, in combination with the general feature of rule chaining. See Section 10.4

[Chains of Implicit Rules], page 117.

• In System V and 4.3 BSD make, ﬁles found by VPATH search (see Section 4.4 [Searching

Directories for Prerequisites], page 25) have their names changed inside recipes. We

feel it is much cleaner to always use automatic variables and thus make this feature

obsolete.

• In some Unix makes, the automatic variable $* appearing in the prerequisites of a rule

has the amazingly strange “feature” of expanding to the full name of the target of that

rule. We cannot imagine what went on in the minds of Unix make developers to do

this; it is utterly inconsistent with the normal deﬁnition of $*.

• In some Unix makes, implicit rule search (see Chapter 10 [Using Implicit Rules],

page 111) is apparently done for all targets, not just those without recipes. This

means you can do:

foo.o:

cc -c foo.c

and Unix make will intuit that foo.o depends on foo.c.

We feel that such usage is broken. The prerequisite properties of make are well-deﬁned

(for GNU make, at least), and doing such a thing simply does not ﬁt the model.

• GNU make does not include any built-in implicit rules for compiling or preprocessing

EFL programs. If we hear of anyone who is using EFL, we will gladly add them.

• It appears that in SVR4 make, a suﬃx rule can be speciﬁed with no recipe, and it is

treated as if it had an empty recipe (see Section 5.9 [Empty Recipes], page 57). For

example:

.c.a:

will override the built-in .c.a suﬃx rule.

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