# $NetBSD: cond-token-plain.mk,v 1.10 2021/01/21 14:08:09 rillig Exp $ # # Tests for plain tokens (that is, string literals without quotes) # in .if conditions. .MAKEFLAGS: -dc .if ${:Uvalue} != value . error .endif # Malformed condition since comment parsing is done in an early phase # and removes the '#' and everything behind it long before the condition # parser gets to see it. # # XXX: The error message is missing for this malformed condition. # The right-hand side of the comparison is just a '"', before unescaping. .if ${:U} != "#hash" . error .endif # To get a '#' into a condition, it has to be escaped using a backslash. # This prevents the comment parser from removing it, and in turn, it becomes # visible to CondParser_String. .if ${:U\#hash} != "\#hash" . error .endif # Since 2002-12-30, and still as of 2020-09-11, CondParser_Token handles # the '#' specially, even though at this point, there should be no need for # comment handling anymore. The comments are supposed to be stripped off # in a very early parsing phase. # # See https://gnats.netbsd.org/19596 for example makefiles demonstrating the # original problems. This workaround is probably not needed anymore. # # XXX: Missing error message for the malformed condition. The right-hand # side before unescaping is double-quotes, backslash, backslash. .if ${:U\\} != "\\#hash" . error .endif # The right-hand side of a comparison is not parsed as a token, therefore # the code from CondParser_Token does not apply to it. # TODO: Explain the consequences. # TODO: Does this mean that more syntactic variants are allowed here? .if ${:U\#hash} != \#hash . error .endif # XXX: What is the purpose of treating an escaped '#' in the following # condition as a comment? And why only at the beginning of a token, # just as in the shell? .if 0 \# This is treated as a comment, but why? . error .endif # Ah, ok, this can be used to add an end-of-condition comment. But does # anybody really use this? This is neither documented nor obvious since # the '#' is escaped. It's much clearer to write a comment in the line # above the condition. .if ${0 \# comment :?yes:no} != no . error .endif .if ${1 \# comment :?yes:no} != yes . error .endif # Usually there is whitespace around the comparison operator, but this is # not required. .if ${UNDEF:Uundefined}!=undefined . error .endif .if ${UNDEF:U12345}>12345 . error .endif .if ${UNDEF:U12345}<12345 . error .endif .if (${UNDEF:U0})||0 . error .endif # Only the comparison operator terminates the comparison operand, and it's # a coincidence that the '!' is both used in the '!=' comparison operator # as well as for negating a comparison result. # # The boolean operators '&' and '|' don't terminate a comparison operand. .if ${:Uvar}&&name != "var&&name" . error .endif .if ${:Uvar}||name != "var||name" . error .endif # A bare word may appear alone in a condition, without any comparison # operator. It is implicitly converted into defined(bare). .if bare . error .else . info A bare word is treated like defined(...), and the variable $\ 'bare' is not defined. .endif VAR= defined .if VAR . info A bare word is treated like defined(...). .else . error .endif # Bare words may be intermixed with variable expressions. .if V${:UA}R . info ok .else . error .endif # In bare words, even undefined variables are allowed. Without the bare # words, undefined variables are not allowed. That feels inconsistent. .if V${UNDEF}AR . info Undefined variables in bare words expand to an empty string. .else . error .endif .if 0${:Ux00} . error .else . info Numbers can be composed from literals and variable expressions. .endif .if 0${:Ux01} . info Numbers can be composed from literals and variable expressions. .else . error .endif # If the right-hand side is missing, it's a parse error. .if "" == . error .else . error .endif # If the left-hand side is missing, it's a parse error as well, but without # a specific error message. .if == "" . error .else . error .endif # The '\\' is not a line continuation. Neither is it an unquoted string # literal. Instead, it is parsed as a function argument (ParseFuncArg), # and in that context, the backslash is just an ordinary character. The # function argument thus stays '\\' (2 backslashes). This string is passed # to FuncDefined, and since there is no variable named '\\', the condition # evaluates to false. .if \\ . error .else . info The variable '\\' is not defined. .endif ${:U\\\\}= backslash .if \\ . info Now the variable '\\' is defined. .else . error .endif # Anything that doesn't start with a double quote is considered a "bare word". # Strangely, a bare word may contain double quotes inside. Nobody should ever # depend on this since it may well be unintended. See CondParser_String. .if "unquoted\"quoted" != unquoted"quoted . error .endif # FIXME: In CondParser_String, Var_Parse returns var_Error without a # corresponding error message. .if $$$$$$$$ != "" . error .else . error .endif # See cond-token-string.mk for similar tests where the condition is enclosed # in "quotes". all: @:;