# $NetBSD: var-op-sunsh.mk,v 1.10 2022/02/09 21:09:24 rillig Exp $
#
# Tests for the :sh= variable assignment operator, which runs its right-hand
# side through the shell.  It is a seldom-used alternative to the !=
# assignment operator, adopted from Sun make.

.MAKEFLAGS: -dL			# Enable sane error messages

# This is the idiomatic form of the Sun shell assignment operator.
# The assignment operator is directly preceded by the ':sh'.
VAR:sh=		echo colon-sh
.if ${VAR} != "colon-sh"
.  error
.endif

# It is also possible to have whitespace around the :sh assignment
# operator modifier.
VAR :sh =	echo colon-sh-spaced
.if ${VAR} != "colon-sh-spaced"
.  error
.endif

# Until 2020-10-04, the ':sh' could even be followed by other characters.
# This was neither documented by NetBSD make nor by Solaris make and was
# an implementation error.
#
# Since 2020-10-04, this is a normal variable assignment to the variable named
# 'VAR:shell', using the '=' assignment operator.
VAR:shell=	echo colon-shell
# The variable name needs to be generated using a ${:U...} expression because
# it is not possible to express the ':' as part of a literal variable name,
# see ParseVarname.
.if ${${:UVAR\:shell}} != "echo colon-shell"
.  error
.endif

# Several colons can syntactically appear in a variable name.
# Until 2020-10-04, the last of them was interpreted as the ':sh'
# assignment operator.
#
# Since 2020-10-04, the colons are part of the variable name.
VAR:shoe:shore=	echo two-colons
.if ${${:UVAR\:shoe\:shore}} != "echo two-colons"
.  error
.endif

# Until 2020-10-04, the following expression was wrongly marked as
# a parse error.  This was because the parser for variable assignments
# just looked for the previous ":sh", without taking any contextual
# information into account.
#
# There are two different syntactical elements that look exactly the same:
# The variable modifier ':sh' and the assignment operator modifier ':sh'.
# Intuitively this variable name contains the variable modifier, but until
# 2020-10-04, the parser regarded it as an assignment operator modifier, in
# Parse_Var.
VAR.${:Uecho 123:sh}=	ok-123
.if ${VAR.123} != "ok-123"
.  error
.endif

# Same pattern here. Until 2020-10-04, the ':sh' inside the nested expression
# was taken for the :sh assignment operator modifier, even though it was
# escaped by a backslash.
VAR.${:U echo\:shell}=	ok-shell
.if ${VAR.${:U echo\:shell}} != "ok-shell"
.  error
.endif

# Until 2020-10-04, the word 'shift' was also affected since it starts with
# ':sh'.
VAR.key:shift=		Shift
.if ${${:UVAR.key\:shift}} != "Shift"
.  error
.endif

# Just for fun: The code in Parse_IsVar allows for multiple appearances of
# the ':sh' assignment operator modifier.  Let's see what happens ...
#
# Well, the end result is correct but the way until there is rather
# adventurous.  This only works because the parser replaces each and every
# whitespace character that is not nested with '\0' (see Parse_Var).
# The variable name therefore ends before the first ':sh', and the last
# ':sh' turns the assignment operator into the shell command evaluation.
# Parse_Var completely trusts Parse_IsVar to properly verify the syntax.
#
# The ':sh' is the only word that may occur between the variable name and
# the assignment operator at nesting level 0.  All other words would lead
# to a parse error since the left-hand side of an assignment must be
# exactly one word.
VAR :sh :sh :sh :sh=	echo multiple
.if ${VAR} != "multiple"
.  error
.endif

# The word ':sh' is not the only thing that can occur after a variable name.
# Since the parser just counts braces and parentheses instead of properly
# expanding nested expressions, the token ' :sh' can be used to add arbitrary
# text between the variable name and the assignment operator, it just has to
# be enclosed in braces or parentheses.
#
# Since the text to the left of the assignment operator '=' does not end with
# ':sh', the effective assignment operator becomes '=', not '!='.
VAR :sh(Put a comment here)=	comment in parentheses
.if ${VAR} != "comment in parentheses"
.  error
.endif

# The unintended comment can include multiple levels of nested braces and
# parentheses.  Braces and parentheses are interchangeable, that is, a '(' can
# be closed by either ')' or '}'.  These braces and parentheses are only
# counted by Parse_IsVar, in particular Parse_Var doesn't see them.
VAR :sh{Put}((((a}{comment}}}}{here}=	comment in braces
.if ${VAR} != "comment in braces"
.  error
.endif

# The assignment modifier ':sh' can be combined with the assignment operator
# '+='.  In such a case the ':sh' is silently ignored, and the effective
# assignment operator is '+='.
#
# XXX: This combination should not be allowed at all, as it is confusing.
VAR=		one
VAR :sh +=	echo two
.if ${VAR} != "one echo two"
.  error ${VAR}
.endif

# The assignment modifier ':sh' can be combined with the assignment operator
# '!='.  In such a case the ':sh' is silently ignored, and the effective
# assignment operator is '!=', just like with '+=' or the other compound
# assignment operators.
#
# XXX: This combination should not be allowed at all, as it is confusing.
VAR :sh !=	echo echo echo echo spaces-around
.if ${VAR} != "echo echo echo spaces-around"
.  error ${VAR}
.endif

# If there is no space between the variable name and the assignment modifier
# ':sh', the ':sh' becomes part of the variable name, as the parser only
# expects a single assignment modifier to the left of the '=', which in this
# case is the '!'.
VAR:sh !=	echo echo echo echo space-after
.if ${${:UVAR\:sh}} != "echo echo echo space-after"
.  error ${${:UVAR\:sh}}
.endif

all: .PHONY