[PATCH] warn when taking the address of a built-in function

[PATCH] warn when taking the address of a built-in function

[Luc Van Oostenryck]

Built-in functions are meant to be expanded by the compiler. As such,
they don't have an address.

So, issue an error when trying take the address of a built-in function.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 evaluate.c                 |  4 ++++
 validation/builtin-arith.c | 25 +++++++++++++++----------
 2 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/evaluate.c b/evaluate.c
index 3ff76fa85e14..d742025287cd 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -1787,6 +1787,8 @@ static struct symbol *degenerate(struct expression *expr)
 			expression_error(expr, "strange non-value function or array");
 			return &bad_ctype;
 		}
+		if (ctype->builtin)
+			sparse_error(expr->pos, "taking the address of built-in function '%s'", show_ident(ctype->ident)); 
 		*expr = *expr->unop;
 		ctype = create_pointer(expr, ctype, 1);
 		expr->ctype = ctype;
@@ -1807,6 +1809,8 @@ static struct symbol *evaluate_addressof(struct expression *expr)
 		return NULL;
 	}
 	ctype = op->ctype;
+	if (ctype->builtin)
+		sparse_error(expr->pos, "taking the address of built-in function '%s'", show_ident(ctype->ident));
 	*expr = *op->unop;
 
 	mark_addressable(expr);
diff --git a/validation/builtin-arith.c b/validation/builtin-arith.c
index 7aabbcb1bd58..3ce593045b37 100644
--- a/validation/builtin-arith.c
+++ b/validation/builtin-arith.c
@@ -31,22 +31,27 @@ void test(void (*fun)(void))
 /*
  * check-name: builtin arithmetic
  * check-command: sparse -Wno-decl $file
- * check-known-to-fail
  *
  * check-error-start
-builtin-arith.c:10:xx: error: ...
-builtin-arith.c:11:xx: error: ...
+builtin-arith.c:10:14: error: taking the address of built-in function '__builtin_trap'
+builtin-arith.c:11:13: error: taking the address of built-in function '__builtin_trap'
+builtin-arith.c:12:14: error: taking the address of built-in function '__builtin_trap'
+builtin-arith.c:13:14: error: taking the address of built-in function '__builtin_trap'
 builtin-arith.c:13:29: error: arithmetics on pointers to functions
+builtin-arith.c:14:14: error: taking the address of built-in function '__builtin_trap'
 builtin-arith.c:14:29: error: arithmetics on pointers to functions
+builtin-arith.c:15:14: error: taking the address of built-in function '__builtin_trap'
 builtin-arith.c:15:29: error: arithmetics on pointers to functions
-builtin-arith.c:18:xx: error: ...
-builtin-arith.c:19:xx: error: ...
-builtin-arith.c:21:xx: error: ...
-builtin-arith.c:22:xx: error: ...
-builtin-arith.c:23:xx: error: ...
-builtin-arith.c:24:xx: error: ...
-builtin-arith.c:25:xx: error: ...
+builtin-arith.c:18:21: error: taking the address of built-in function '__builtin_trap'
+builtin-arith.c:19:29: error: taking the address of built-in function '__builtin_trap'
+builtin-arith.c:21:14: error: taking the address of built-in function '__builtin_trap'
+builtin-arith.c:22:14: error: taking the address of built-in function '__builtin_trap'
+builtin-arith.c:23:14: error: taking the address of built-in function '__builtin_trap'
+builtin-arith.c:24:21: error: taking the address of built-in function '__builtin_trap'
+builtin-arith.c:25:21: error: taking the address of built-in function '__builtin_trap'
+builtin-arith.c:27:9: error: taking the address of built-in function '__builtin_trap'
 builtin-arith.c:27:24: error: subtraction of functions? Share your drugs
+builtin-arith.c:28:15: error: taking the address of built-in function '__builtin_trap'
 builtin-arith.c:28:13: error: subtraction of functions? Share your drugs
  * check-error-end
  */
-- 
2.28.0