* Am I missing anything? Yes. The recipe's text, which you can see with eg:
mad@shuttle:~/tmp/colomar-2025-09-10$ make -n -p 2>&1 | grep -A26 ^all: all: # Implicit rule search has not been done. ... # Load=8/32=25%, Rehash=0, Collisions=1/12=8% # recipe to execute (from 'Makefile', line 5): echo $(foo) Mad@shuttle:~/tmp/colomar-2025-09-10$ ... doesn't contain the value of foo but a reference to it. Recipe definition is evaluated like recursively-expanded assignment (=), rather than simply-expanded assignment (:=). Perhaps this is best documented by https://www.gnu.org/software/make/manual/html_node/Variables-in-Recipes.html, although perhaps https://www.gnu.org/software/make/manual/html_node/Recursive-Assignment.html gets more to the heart of the matter, with "This flavor of variable is the only sort supported by most other versions of make", which I might take to mean that anything that doesn't explicitly talk about this newfangled := assignment isn't using it. You can see the... legacy of history in the way "The Two Flavors of Variables" at https://www.gnu.org/software/make/manual/html_node/Flavors.html has four subsections rather than the titular two, one of which talks about the really newfangled (POSIX Issue 8 only being standardized in 2024) :::= assignment. ________________________________ From: bug-make-bounces+martin.dorey=hds....@gnu.org on behalf of Alejandro Colomar Sent: Wednesday, September 10, 2025 13:33 To: bug-make@gnu.org Subject: [BUG] undefined variable used in recipe before undefine directive Hi, I think this looks like a bug, unless I'm forgetting some details about how variables are expanded within recipes. alx@debian:~/tmp/bug$ ls Makefile alx@debian:~/tmp/bug$ cat Makefile | nl -ba 1 MAKEFLAGS += --warn-undefined-variables 2 3 foo := foo 4 5 all:; echo $(foo) 6 7 undefine foo alx@debian:~/tmp/bug$ make Makefile:5: warning: undefined variable 'foo' echo As I understand it, the variable foo is expanded immediately in the definition of the recipe, and make(1) shouldn't care if I undefine it after the definition of the recipe, right? make(1) should create the recipe with the contents of the variable, and not with the variable itself. Am I missing anything? I'm using Debian Sid: $ make --version | head -n1 GNU Make 4.4.1 Have a lovely night! Alex -- <https://www.alejandro-colomar.es> Use port 80 (that is, <...:80/>).
