bmake: unit-tests/var-op-expand.mk - 20201101 vs. 20201117 changes

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About: bmake a BSD make tool (derived from NetBSD’s make).

var-op-expand.mk (bmake-20201101)	:	var-op-expand.mk (bmake-20201117)

# $NetBSD: var-op-expand.mk,v 1.2 2020/08/16 14:25:16 rillig Exp $		# $NetBSD: var-op-expand.mk,v 1.4 2020/11/08 14:00:52 rillig Exp $
#		#
# Tests for the := variable assignment operator, which expands its		# Tests for the := variable assignment operator, which expands its
# right-hand side.		# right-hand side.

# TODO: Implementation		# TODO: Implementation


		# XXX: edge case: When a variable name refers to an undefined variable, the
		# behavior differs between the '=' and the ':=' assignment operators.
		# This bug exists since var.c 1.42 from 2000-05-11.
		#
		# The '=' operator expands the undefined variable to an empty string, thus
		# assigning to VAR_ASSIGN_. In the name of variables to be set, it should
		# really be forbidden to refer to undefined variables.
		#
		# The ':=' operator expands the variable name twice. In one of these
		# expansions, the undefined variable expression is preserved (controlled by
		# preserveUndefined in VarAssign_EvalSubst), in the other expansion it expands
		# to an empty string. This way, 2 variables are created using a single
		# variable assignment. It's magic. :-/
		.MAKEFLAGS: -dv
		VAR_ASSIGN_${UNDEF}= undef value
		VAR_SUBST_${UNDEF}:= undef value
		.MAKEFLAGS: -d0

all:		all:
@:;		@:;

End of changes. 2 change blocks.
1 lines changed or deleted		19 lines changed or added