kconfig: improve the recursive dependency report

This commit improves the messages of the recursive dependency.
Currently, sym->dir_dep.expr is not checked. Hence, any dependency
in property visibility is regarded as the dependency of the symbol.

[Test Code 1]

config A
bool "a"
depends on B

config B
bool "b"
depends on A

[Test Code 2]

config A
bool "a" if B

config B
bool "b"
depends on A

For both cases above, the same message is displayed:

symbol B depends on A
symbol A depends on B

This commit changes the message for the latter, like this:

symbol B depends on A
symbol A prompt is visible depending on B

Also, 'select' and 'imply' are distinguished.

Signed-off-by: Masahiro Yamada <[e-mail]>
Tested-by: Dirk Gouders <[e-mail]>

scripts/kconfig/symbol.c

···
 	struct dep_stack *prev, *next;
 	struct symbol *sym;
 	struct property *prop;
-	struct expr *expr;
+	struct expr **expr;
 } *check_top;
 
 static void dep_stack_insert(struct dep_stack *stack, struct symbol *sym)
···
 			fprintf(stderr, "%s:%d:error: recursive dependency detected!\n",
 				prop->file->name, prop->lineno);
 
-		if (stack->expr) {
-			fprintf(stderr, "%s:%d:\tsymbol %s %s value contains %s\n",
-				prop->file->name, prop->lineno,
-				sym->name ? sym->name : "<choice>",
-				prop_get_type_name(prop->type),
-				next_sym->name ? next_sym->name : "<choice>");
-		} else if (stack->prop) {
-			fprintf(stderr, "%s:%d:\tsymbol %s depends on %s\n",
-				prop->file->name, prop->lineno,
-				sym->name ? sym->name : "<choice>",
-				next_sym->name ? next_sym->name : "<choice>");
-		} else if (sym_is_choice(sym)) {
+		if (sym_is_choice(sym)) {
 			fprintf(stderr, "%s:%d:\tchoice %s contains symbol %s\n",
 				menu->file->name, menu->lineno,
 				sym->name ? sym->name : "<choice>",
···
 				menu->file->name, menu->lineno,
 				sym->name ? sym->name : "<choice>",
 				next_sym->name ? next_sym->name : "<choice>");
-		} else {
-			fprintf(stderr, "%s:%d:\tsymbol %s is selected or implied by %s\n",
+		} else if (stack->expr == &sym->dir_dep.expr) {
+			fprintf(stderr, "%s:%d:\tsymbol %s depends on %s\n",
 				prop->file->name, prop->lineno,
 				sym->name ? sym->name : "<choice>",
+				next_sym->name ? next_sym->name : "<choice>");
+		} else if (stack->expr == &sym->rev_dep.expr) {
+			fprintf(stderr, "%s:%d:\tsymbol %s is selected by %s\n",
+				prop->file->name, prop->lineno,
+				sym->name ? sym->name : "<choice>",
+				next_sym->name ? next_sym->name : "<choice>");
+		} else if (stack->expr == &sym->implied.expr) {
+			fprintf(stderr, "%s:%d:\tsymbol %s is implied by %s\n",
+				prop->file->name, prop->lineno,
+				sym->name ? sym->name : "<choice>",
+				next_sym->name ? next_sym->name : "<choice>");
+		} else if (stack->expr) {
+			fprintf(stderr, "%s:%d:\tsymbol %s %s value contains %s\n",
+				prop->file->name, prop->lineno,
+				sym->name ? sym->name : "<choice>",
+				prop_get_type_name(prop->type),
+				next_sym->name ? next_sym->name : "<choice>");
+		} else {
+			fprintf(stderr, "%s:%d:\tsymbol %s %s is visible depending on %s\n",
+				prop->file->name, prop->lineno,
+				sym->name ? sym->name : "<choice>",
+				prop_get_type_name(prop->type),
 				next_sym->name ? next_sym->name : "<choice>");
 		}
 	}
···
 
 	dep_stack_insert(&stack, sym);
 
+	stack.expr = &sym->dir_dep.expr;
+	sym2 = sym_check_expr_deps(sym->dir_dep.expr);
+	if (sym2)
+		goto out;
+
+	stack.expr = &sym->rev_dep.expr;
 	sym2 = sym_check_expr_deps(sym->rev_dep.expr);
 	if (sym2)
 		goto out;
 
+	stack.expr = &sym->implied.expr;
 	sym2 = sym_check_expr_deps(sym->implied.expr);
 	if (sym2)
 		goto out;
+
+	stack.expr = NULL;
 
 	for (prop = sym->prop; prop; prop = prop->next) {
 		if (prop->type == P_CHOICE || prop->type == P_SELECT ||
···
 			break;
 		if (prop->type != P_DEFAULT || sym_is_choice(sym))
 			continue;
-		stack.expr = prop->expr;
+		stack.expr = &prop->expr;
 		sym2 = sym_check_expr_deps(prop->expr);
 		if (sym2)
 			break;

scripts/kconfig/tests/err_recursive_dep/expected_stderr

···
 Kconfig:11:error: recursive dependency detected!
-Kconfig:11:	symbol B is selected or implied by B
+Kconfig:11:	symbol B is selected by B
 For a resolution refer to Documentation/kbuild/kconfig-language.txt
 subsection "Kconfig recursive dependency limitations"
 
···
 subsection "Kconfig recursive dependency limitations"
 
 Kconfig:32:error: recursive dependency detected!
-Kconfig:32:	symbol D2 is selected or implied by D1
+Kconfig:32:	symbol D2 is selected by D1
 Kconfig:27:	symbol D1 depends on D2
 For a resolution refer to Documentation/kbuild/kconfig-language.txt
 subsection "Kconfig recursive dependency limitations"
 
 Kconfig:37:error: recursive dependency detected!
 Kconfig:37:	symbol E1 depends on E2
-Kconfig:42:	symbol E2 is selected or implied by E1
+Kconfig:42:	symbol E2 is implied by E1
 For a resolution refer to Documentation/kbuild/kconfig-language.txt
 subsection "Kconfig recursive dependency limitations"