This code snippet:
static void bar(void const *arg)
{
int (*foo)(void) = arg;
}
produces the following warning:
test.c:4:28: warning: incorrect type in initializer (different modifiers)
test.c:4:28: expected int ( *foo )( ... )
test.c:4:28: got void const *arg
which is caused by the fact that the function pointer 'foo' is not annotated
as being a pointer to const data. However, dereferencing a function pointer
does not produce an lvalue, so a function pointer points to const data by
definition, and we should treat it accordingly.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
evaluate.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/evaluate.c b/evaluate.c
index 66556150ddac..6428312f3e61 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -794,6 +794,14 @@ static unsigned long target_qualifiers(struct symbol *type)
unsigned long mod = type->ctype.modifiers & MOD_IGN;
if (type->ctype.base_type && type->ctype.base_type->type == SYM_ARRAY)
mod = 0;
+
+ /*
+ * Dereferencing a function pointer does not produce an lvalue,
+ * which means its target is implicitly 'const', and assigning
+ * a pointer-to-const value to it is ok.
+ */
+ if (type->ctype.base_type && type->ctype.base_type->type == SYM_FN)
+ mod |= MOD_CONST;
return mod;
}
--
1.8.3.2
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