( Suffix Rules

Info Catalog ( Last Resort ( Implicit Rules ( Implicit Rule Search
 10.7 Old-Fashioned Suffix Rules
 "Suffix rules" are the old-fashioned way of defining implicit rules for
 `make'.  Suffix rules are obsolete because pattern rules are more
 general and clearer.  They are supported in GNU `make' for
 compatibility with old makefiles.  They come in two kinds:
 "double-suffix" and "single-suffix".
    A double-suffix rule is defined by a pair of suffixes: the target
 suffix and the source suffix.  It matches any file whose name ends with
 the target suffix.  The corresponding implicit prerequisite is made by
 replacing the target suffix with the source suffix in the file name.  A
 two-suffix rule whose target and source suffixes are `.o' and `.c' is
 equivalent to the pattern rule `%.o : %.c'.
    A single-suffix rule is defined by a single suffix, which is the
 source suffix.  It matches any file name, and the corresponding implicit
 prerequisite name is made by appending the source suffix.  A
 single-suffix rule whose source suffix is `.c' is equivalent to the
 pattern rule `% : %.c'.
    Suffix rule definitions are recognized by comparing each rule's
 target against a defined list of known suffixes.  When `make' sees a
 rule whose target is a known suffix, this rule is considered a
 single-suffix rule.  When `make' sees a rule whose target is two known
 suffixes concatenated, this rule is taken as a double-suffix rule.
    For example, `.c' and `.o' are both on the default list of known
 suffixes.  Therefore, if you define a rule whose target is `.c.o',
 `make' takes it to be a double-suffix rule with source suffix `.c' and
 target suffix `.o'.  Here is the old-fashioned way to define the rule
 for compiling a C source file:
              $(CC) -c $(CFLAGS) $(CPPFLAGS) -o $@ $<
    Suffix rules cannot have any prerequisites of their own.  If they
 have any, they are treated as normal files with funny names, not as
 suffix rules.  Thus, the rule:
      .c.o: foo.h
              $(CC) -c $(CFLAGS) $(CPPFLAGS) -o $@ $<
 tells how to make the file `.c.o' from the prerequisite file `foo.h',
 and is not at all like the pattern rule:
      %.o: %.c foo.h
              $(CC) -c $(CFLAGS) $(CPPFLAGS) -o $@ $<
 which tells how to make `.o' files from `.c' files, and makes all `.o'
 files using this pattern rule also depend on `foo.h'.
    Suffix rules with no commands are also meaningless.  They do not
 remove previous rules as do pattern rules with no commands (
 Canceling Implicit Rules Canceling Rules.).  They simply enter the
 suffix or pair of suffixes concatenated as a target in the data base.
    The known suffixes are simply the names of the prerequisites of the
 special target `.SUFFIXES'.  You can add your own suffixes by writing a
 rule for `.SUFFIXES' that adds more prerequisites, as in:
      .SUFFIXES: .hack .win
 which adds `.hack' and `.win' to the end of the list of suffixes.
    If you wish to eliminate the default known suffixes instead of just
 adding to them, write a rule for `.SUFFIXES' with no prerequisites.  By
 special dispensation, this eliminates all existing prerequisites of
 `.SUFFIXES'.  You can then write another rule to add the suffixes you
 want.  For example,
      .SUFFIXES:            # Delete the default suffixes
      .SUFFIXES: .c .o .h   # Define our suffix list
    The `-r' or `--no-builtin-rules' flag causes the default list of
 suffixes to be empty.
    The variable `SUFFIXES' is defined to the default list of suffixes
 before `make' reads any makefiles.  You can change the list of suffixes
 with a rule for the special target `.SUFFIXES', but that does not alter
 this variable.
Info Catalog ( Last Resort ( Implicit Rules ( Implicit Rule Search
automatically generated byinfo2html