Target specific += has strange behaviour

[Oliver Schmidt]

Hi,

the following makefile:

======== Makefile start ===============
.PHONY: targ targA targB targC

targ: targA targB targC

targA targB targC:
        @echo "$@: T=<$T>"

T := 1

targA: T  = 2
targA: T += 3

targB: T := 2
targB: T += 3

targC: T  = 2
======== Makefile end   ===============


gives the output:

targA: T=<1 2 3>
targB: T=<2 3>
targC: T=<2>


This happens with GNU Make Version 3.79.1 and 3.80.

In my opinion the output for targA should be "targA: T=<2 3>".

Best regards,
Oliver