question about $$+

[ali hagigat]

Secondary Expansion of Explicit Rules
.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 respec-
tively. 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 respectively.
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In page 21 of the make manual, there is an example of secondary
expansion. The written result of the third $$+ seems wrong. It should
be:
foo.1 bar.1 foo.2 bar.2 foo.1 foo.1 bar.1 foo.1 bar.1
Please correct me if I am wrong. Thank you.