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[bug #52028] Preventing infinite recursions when make is invoked from re

From: anonymous
Subject: [bug #52028] Preventing infinite recursions when make is invoked from recipes
Date: Fri, 15 Sep 2017 01:47:31 -0400 (EDT)
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:54.0) Gecko/20100101 Firefox/54.0


                 Summary: Preventing infinite recursions when make is invoked
from recipes
                 Project: make
            Submitted by: None
            Submitted on: Fri 15 Sep 2017 05:47:30 AM UTC
                Severity: 3 - Normal
              Item Group: Enhancement
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
       Component Version: 4.1
        Operating System: POSIX-Based
           Fixed Release: None
           Triage Status: None



Consider this Makefile:

a : 
        echo a1
        $(MAKE) b
        echo a2

b :
        echo b1
        $(MAKE) a
        echo b2

Building either a or b will cause infinite recursion.

It is possible to work around this with a template, similar to the following:

SHELL := bash
exportable = $(shell echo $(1) | sed 's%[^[:alnum:]_]%_%g')
define make
$(eval d := $(strip $(call exportable,$(1))))
$(eval f := $(if $(strip $(2)), -f $(realpath $(strip $2))))
if [ "$$_making_$(d)" != "$@" ]; then \
        export _making_$(d)="$@"; \
        $(MAKE) $(f) "$(strip $(1))"; \

a : 
        echo a1
        $(call make,b)
        echo a2

b :
        echo b1
        $(call make,a)
        echo b2

Running with -s produces:

Making b instead:

This is an enhancement/optional feature request:

Add a command $(make ...) or modify interpretation of $(MAKE) in recipes,
which functions in a way similar to the work around template provided.

The template is highly non-portable, uses regular expressions and invokes a
shell, pollutes environment variables without cleaning up, and it is very hard
to understand (it took several hours of experimenting to come up with).

Reasons to deny the request that I can think of:

It may be considered "bad design" to specify dependencies within a recipe. The
above example is basically a circular dependency.

Counter arguments:

GNU Make allows recursion which therefore exposes an infinite recursion bug. A
circular dependency specified normally will not cause an infinite recursion.
GNU Make should treat these the same way.

The dependency specified by a recursive make is different to a normal
dependency in that it allows for control over ordering of recipe instructions.
This may open up more patterns for make to be used more heuristically
(dependencies do not need to be rigidly pre-determined).

I'd quite like to try implementing this feature because I have specific use
cases for it. 

Sam Moore


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