Introduce support for recognizing address constants created either
- explicitly by referencing a static storage duration object by means
of the unary & operator,
- implicitly by the use of an expression of array or function type.
Initially tag an expression as being an address constant at the primary
expression level, i.e. upon encountering a symbol designating an object of
static storage duration in primary_expression().
Carry the address constant flag over to the *-preop wrapped expression
created by evaluate_symbol_expression().
When dereferencing such a *-preop wrapped expression, make
evaluate_addressof() keep any address constant flag for the unwrapped
expression.
Signed-off-by: Nicolai Stange <nicstange@xxxxxxxxx>
---
evaluate.c | 3 ++-
expression.c | 8 ++++++++
validation/constexpr-addr-of-static.c | 36 +++++++++++++++++++++++++++++++++++
3 files changed, 46 insertions(+), 1 deletion(-)
create mode 100644 validation/constexpr-addr-of-static.c
diff --git a/evaluate.c b/evaluate.c
index 300bfbe..91f89f4 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -70,9 +70,11 @@ static struct symbol *evaluate_symbol_expression(struct expression *expr)
addr->symbol = sym;
addr->symbol_name = expr->symbol_name;
addr->ctype = &lazy_ptr_ctype; /* Lazy evaluation: we need to do a proper job if somebody does &sym */
+ addr->constexpr_flags = expr->constexpr_flags;
expr->type = EXPR_PREOP;
expr->op = '*';
expr->unop = addr;
+ expr->constexpr_flags = CONSTEXPR_FLAG_NONE;
/* The type of a symbol is the symbol itself! */
expr->ctype = sym;
@@ -1682,7 +1684,6 @@ static struct symbol *evaluate_addressof(struct expression *expr)
}
ctype = op->ctype;
*expr = *op->unop;
- expr->constexpr_flags = CONSTEXPR_FLAG_NONE;
if (expr->type == EXPR_SYMBOL) {
struct symbol *sym = expr->symbol;
diff --git a/expression.c b/expression.c
index b2d5eb4..11fb9cd 100644
--- a/expression.c
+++ b/expression.c
@@ -440,6 +440,14 @@ struct token *primary_expression(struct token *token, struct expression **tree)
}
expr->symbol_name = token->ident;
expr->symbol = sym;
+
+ /*
+ * A pointer to an lvalue designating a static storage
+ * duration object is an address constant [6.6(9)].
+ */
+ if(sym && (sym->ctype.modifiers & (MOD_TOPLEVEL | MOD_STATIC)))
+ expr->constexpr_flags = CONSTEXPR_FLAG_ADDR_CONST;
+
token = next;
break;
}
diff --git a/validation/constexpr-addr-of-static.c b/validation/constexpr-addr-of-static.c
new file mode 100644
index 0000000..a3af99a
--- /dev/null
+++ b/validation/constexpr-addr-of-static.c
@@ -0,0 +1,36 @@
+static int a = 1;
+static int b[2] = {1, 1};
+static void c(void) {}
+
+static int *d = &a; // OK
+static int *e = d; // KO
+static int *f = b; // OK
+
+static void (*g)(void) = c; // OK
+static void (*h)(void) = &c; // OK
+
+static int *i = &*&a; // OK
+static int *j = &*b; // OK
+static int *k = &*d; // KO
+
+
+static void l(void) {
+ int a = 1;
+ static int *b = &a; // KO
+}
+
+static void m(void) {
+ static int a = 1;
+ static int *b = &a; // OK
+}
+
+/*
+ * check-name: address of static object constness verification.
+ * check-command: sparse -Wconstexpr-not-const $file
+ *
+ * check-error-start
+constexpr-addr-of-static.c:6:17: warning: non-constant initializer for static object
+constexpr-addr-of-static.c:14:19: warning: non-constant initializer for static object
+constexpr-addr-of-static.c:19:26: warning: non-constant initializer for static object
+ * check-error-end
+ */
--
2.7.0
--
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