[PATCH] kconfig: warn about complex selects

[Vegard Nossum]

"Complex selects" are selects that depend on symbols with dependencies. These
are effectively circumventing the rest of the dependency chains of kconfig,
often leading to build errors.

Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxx>
---
 scripts/kconfig/symbol.c |   31 ++++++++++++++++++++++++++++++-
 1 files changed, 30 insertions(+), 1 deletions(-)

diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
index 18f3e5c..e5c3c60 100644
--- a/scripts/kconfig/symbol.c
+++ b/scripts/kconfig/symbol.c
@@ -790,6 +790,24 @@ static struct symbol *sym_check_expr_deps(struct expr *e)
 	return NULL;
 }
 
+bool sym_check_select(struct symbol *sym)
+{
+	struct property *prop;
+
+	for (prop = sym->prop; prop; prop = prop->next) {
+		struct expr *expr = prop->expr;
+
+		if (!expr)
+			continue;
+		if (expr->type == E_SYMBOL)
+			continue;
+
+		return true;
+	}
+
+	return false;
+}
+
 /* return NULL when dependencies are OK */
 static struct symbol *sym_check_sym_deps(struct symbol *sym)
 {
@@ -801,7 +819,18 @@ static struct symbol *sym_check_sym_deps(struct symbol *sym)
 		return sym2;
 
 	for (prop = sym->prop; prop; prop = prop->next) {
-		if (prop->type == P_CHOICE || prop->type == P_SELECT)
+		if (prop->type == P_SELECT) {
+			if (!sym_check_select(prop->expr->left.sym))
+				continue;
+
+			fprintf(stderr, "%s:%d:error: found complex select: "
+				"%s -> %s\n",
+				sym->prop->file->name, sym->prop->lineno,
+				sym->name, prop->expr->left.sym->name);
+			continue;
+		}
+
+		if (prop->type == P_CHOICE)
 			continue;
 		sym2 = sym_check_expr_deps(prop->visible.expr);
 		if (sym2)
-- 
1.5.4.1

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