kconfig: Update to KConfig to version from kernel 4.17

This updates the KConfig system used in backports to the version from
kernel 4.17. In kernel 4.18 some bigger changes to the KConfig system
were introduced which are harder to backport, so start with using this
older version.

This version now generates the zconf.lex.c and zconf.tab.c files from
the original sources, newer kernel versions will delete these files in
a make clean, after that they are now regenerated. We do not ship them
by default any more, so we need lex and yacc.

The Makefile was not copied from the mainline kernel but this is written
specifically for the backports project.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Cc: Anthony Wong <yp@anthonywong.net>

1 files changed, 91 insertions, 2 deletions

diff --git a/backport/kconf/expr.h b/backport/kconf/expr.h
index a73f762c..94a383b2 100644
--- a/backport/kconf/expr.h
+++ b/backport/kconf/expr.h
@@ -74,17 +74,60 @@ enum {
 	S_DEF_COUNT
 };
 
+/*
+ * Represents a configuration symbol.
+ *
+ * Choices are represented as a special kind of symbol and have the
+ * SYMBOL_CHOICE bit set in 'flags'.
+ */
 struct symbol {
+	/* The next symbol in the same bucket in the symbol hash table */
 	struct symbol *next;
+
+	/* The name of the symbol, e.g. "FOO" for 'config FOO' */
 	char *name;
+
+	/* S_BOOLEAN, S_TRISTATE, ... */
 	enum symbol_type type;
+
+	/*
+	 * The calculated value of the symbol. The SYMBOL_VALID bit is set in
+	 * 'flags' when this is up to date. Note that this value might differ
+	 * from the user value set in e.g. a .config file, due to visibility.
+	 */
 	struct symbol_value curr;
+
+	/*
+	 * Values for the symbol provided from outside. def[S_DEF_USER] holds
+	 * the .config value.
+	 */
 	struct symbol_value def[S_DEF_COUNT];
+
+	/*
+	 * An upper bound on the tristate value the user can set for the symbol
+	 * if it is a boolean or tristate. Calculated from prompt dependencies,
+	 * which also inherit dependencies from enclosing menus, choices, and
+	 * ifs. If 'n', the user value will be ignored.
+	 *
+	 * Symbols lacking prompts always have visibility 'n'.
+	 */
 	tristate visible;
+
+	/* SYMBOL_* flags */
 	int flags;
+
+	/* List of properties. See prop_type. */
 	struct property *prop;
+
+	/* Dependencies from enclosing menus, choices, and ifs */
 	struct expr_value dir_dep;
+
+	/* Reverse dependencies through being selected by other symbols */
 	struct expr_value rev_dep;
+
+	/*
+	 * "Weak" reverse dependencies through being implied by other symbols
+	 */
 	struct expr_value implied;
 };
 
@@ -133,7 +176,7 @@ enum prop_type {
 	P_UNKNOWN,
 	P_PROMPT,   /* prompt "foo prompt" or "BAZ Value" */
 	P_COMMENT,  /* text associated with a comment */
-	P_MENU,     /* prompt associated with a menuconfig option */
+	P_MENU,     /* prompt associated with a menu or menuconfig symbol */
 	P_DEFAULT,  /* default y */
 	P_CHOICE,   /* choice value */
 	P_SELECT,   /* select BAR */
@@ -166,22 +209,67 @@ struct property {
 	for (st = sym->prop; st; st = st->next) \
 		if (st->text)
 
+/*
+ * Represents a node in the menu tree, as seen in e.g. menuconfig (though used
+ * for all front ends). Each symbol, menu, etc. defined in the Kconfig files
+ * gets a node. A symbol defined in multiple locations gets one node at each
+ * location.
+ */
 struct menu {
+	/* The next menu node at the same level */
 	struct menu *next;
+
+	/* The parent menu node, corresponding to e.g. a menu or choice */
 	struct menu *parent;
+
+	/* The first child menu node, for e.g. menus and choices */
 	struct menu *list;
+
+	/*
+	 * The symbol associated with the menu node. Choices are implemented as
+	 * a special kind of symbol. NULL for menus, comments, and ifs.
+	 */
 	struct symbol *sym;
+
+	/*
+	 * The prompt associated with the node. This holds the prompt for a
+	 * symbol as well as the text for a menu or comment, along with the
+	 * type (P_PROMPT, P_MENU, etc.)
+	 */
 	struct property *prompt;
+
+	/*
+	 * 'visible if' dependencies. If more than one is given, they will be
+	 * ANDed together.
+	 */
 	struct expr *visibility;
+
+	/*
+	 * Ordinary dependencies from e.g. 'depends on' and 'if', ANDed
+	 * together
+	 */
 	struct expr *dep;
+
+	/* MENU_* flags */
 	unsigned int flags;
+
+	/* Any help text associated with the node */
 	char *help;
+
+	/* The location where the menu node appears in the Kconfig files */
 	struct file *file;
 	int lineno;
+
+	/* For use by front ends that need to store auxiliary data */
 	void *data;
 };
 
+/*
+ * Set on a menu node when the corresponding symbol changes state in some way.
+ * Can be checked by front ends.
+ */
 #define MENU_CHANGED		0x0001
+
 #define MENU_ROOT		0x0002
 
 struct jump_key {
@@ -217,11 +305,12 @@ struct expr *expr_transform(struct expr *e);
 int expr_contains_symbol(struct expr *dep, struct symbol *sym);
 bool expr_depends_symbol(struct expr *dep, struct symbol *sym);
 struct expr *expr_trans_compare(struct expr *e, enum expr_type type, struct symbol *sym);
-struct expr *expr_simplify_unmet_dep(struct expr *e1, struct expr *e2);
 
 void expr_fprint(struct expr *e, FILE *out);
 struct gstr; /* forward */
 void expr_gstr_print(struct expr *e, struct gstr *gs);
+void expr_gstr_print_revdep(struct expr *e, struct gstr *gs,
+			    tristate pr_type, const char *title);
 
 static inline int expr_is_yes(struct expr *e)
 {