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kconfig: fix relational operators for bool and tristate symbols 

Since commit 31847b67be ("kconfig: allow use of relations other than
(in)equality") it is possible to use relational operators in Kconfig
statements. However, those operators give unexpected results when
applied to bool/tristate values:

	(n < y) = y (correct)
	(m < y) = y (correct)
	(n < m) = n (wrong)

This happens because relational operators process bool and tristate
symbols as strings and m sorts before n. It makes little sense to do a
lexicographical compare on bool and tristate values though.

Documentation/kbuild/kconfig-language.txt states that expression can have
a value of 'n', 'm' or 'y' (or 0, 1, 2 respectively for calculations).
Let's make it so for relational comparisons with bool/tristate
expressions as well and document them. If at least one symbol is an
actual string then the lexicographical compare works just as before.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
This commit is contained in:
Nicolas Pitre 2017-11-16 20:06:39 -05:00 committed by Masahiro Yamada
parent cfe17c9bbe
commit 9059a3493e
2 changed files with 19 additions and 9 deletions
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23
Documentation/kbuild/kconfig-language.txt
View File

@ -200,10 +200,14 @@ module state. Dependency expressions have the following syntax:
<expr> ::= <symbol> (1)
<symbol> '=' <symbol> (2)
<symbol> '!=' <symbol> (3)
'(' <expr> ')' (4)
'!' <expr> (5)
<expr> '&&' <expr> (6)
<expr> '||' <expr> (7)
<symbol1> '<' <symbol2> (4)
<symbol1> '>' <symbol2> (4)
<symbol1> '<=' <symbol2> (4)
<symbol1> '>=' <symbol2> (4)
'(' <expr> ')' (5)
'!' <expr> (6)
<expr> '&&' <expr> (7)
<expr> '||' <expr> (8)
Expressions are listed in decreasing order of precedence.
@ -214,10 +218,13 @@ Expressions are listed in decreasing order of precedence.
otherwise 'n'.
(3) If the values of both symbols are equal, it returns 'n',
otherwise 'y'.
(4) Returns the value of the expression. Used to override precedence.
(5) Returns the result of (2-/expr/).
(6) Returns the result of min(/expr/, /expr/).
(7) Returns the result of max(/expr/, /expr/).
(4) If value of <symbol1> is respectively lower, greater, lower-or-equal,
or greater-or-equal than value of <symbol2>, it returns 'y',
otherwise 'n'.
(5) Returns the value of the expression. Used to override precedence.
(6) Returns the result of (2-/expr/).
(7) Returns the result of min(/expr/, /expr/).
(8) Returns the result of max(/expr/, /expr/).
An expression can have a value of 'n', 'm' or 'y' (or 0, 1, 2
respectively for calculations). A menu entry becomes visible when its

5
scripts/kconfig/expr.c
View File

@ -893,7 +893,10 @@ static enum string_value_kind expr_parse_string(const char *str,
switch (type) {
case S_BOOLEAN:
case S_TRISTATE:
return k_string;
val->s = !strcmp(str, "n") ? 0 :
!strcmp(str, "m") ? 1 :
!strcmp(str, "y") ? 2 : -1;
return k_signed;
case S_INT:
val->s = strtoll(str, &tail, 10);
kind = k_signed;