Re: is this a typo on your manual?

[Paul Smith]

Please reply to the list, not privately, then everyone can help and/or
see the answer.


On Wed, 2023-02-15 at 18:19 +0000, Shailan Patel wrote:
> Hello im referring to this
> chapter https://www.gnu.org/software/make/manual/make.html#Secondary-
> Expansion 
> 
> and im referring to this example here:
> 
> The following example will help illustrate these behaviors:
> .SECONDEXPANSION:
> 
> foo: foo.1 bar.1 $$< $$^ $$+    # line #1
> 
> foo: foo.2 bar.2 $$< $$^ $$+    # line #2
> 
> foo: foo.3 bar.3 $$< $$^ $$+    # line #3
> In the first prerequisite list, all three variables ($$<, $$^,
> and $$+) expand to the empty string. In the second, they will have
> values foo.1, foo.1 bar.1, and foo.1 bar.1 respectively. In the third
> they will have values foo.1, foo.1 bar.1 foo.2 bar.2, and foo.1 bar.1
> foo.2 bar.2 foo.1 foo.1 bar.1 foo.1 bar.1 respectively.
> please could you tell me how foo.1 bar.1 foo.2 bar.2 foo.1 foo.1
> bar.1 foo.1 bar.1 is derived?

In line #1 all the variables are empty.

After line #1 parsed, in line #2, the variables have values as computed
in line #1: $$< is "foo.1" and $$^ is "foo.1 bar.1", and $$+ is "foo.1
bar.1".

After line #2 is parsed (when we are parsing line #3) the prerequisites
of "foo" are as follows:

  foo.1 bar.1  (from line #1)
  foo.2 bar.2  (new prereqs added by line #2)
  foo.1        ($$< in line #2)
  foo.1 bar.1  ($$^ in line #2)
  foo.1 bar.1  ($$+ in line #2)