Initializers of static storage duration objects shall be constant
expressions [6.7.8(4)].
Warn if that requirement is not met.
Identify static storage duration objects by having either of
MOD_TOPLEVEL or MOD_STATIC set.
Check an initializer's constness at the lowest possible subobject
level, i.e. at the level of the "assignment-expression" production
in [6.7.8].
For compound objects, make handle_list_initializer() pass the
surrounding object's storage duration modifiers down to
handle_simple_initializer() at subobject initializer evaluation.
Signed-off-by: Nicolai Stange <nicstange@xxxxxxxxx>
---
evaluate.c | 25 +++++++++-
validation/constexpr-init.c | 109 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 133 insertions(+), 1 deletion(-)
create mode 100644 validation/constexpr-init.c
diff --git a/evaluate.c b/evaluate.c
index c38b893..a65cc0c 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -2466,6 +2466,7 @@ static void handle_list_initializer(struct expression *expr,
{
struct expression *e, *last = NULL, *top = NULL, *next;
int jumped = 0;
+ unsigned long old_modifiers;
FOR_EACH_PTR(expr->expr_list, e) {
struct expression **v;
@@ -2520,8 +2521,21 @@ found:
else
v = &top->ident_expression;
- if (handle_simple_initializer(v, 1, lclass, top->ctype))
+ /*
+ * Temporarily copy storage modifiers down from
+ * surrounding type such that
+ * handle_simple_initializer() can check
+ * initializations of subobjects with static storage
+ * duration.
+ */
+ old_modifiers = top->ctype->ctype.modifiers;
+ top->ctype->ctype.modifiers =
+ old_modifiers | (ctype->ctype.modifiers & MOD_STORAGE);
+ if (handle_simple_initializer(v, 1, lclass, top->ctype)) {
+ top->ctype->ctype.modifiers = old_modifiers;
continue;
+ }
+ top->ctype->ctype.modifiers = old_modifiers;
if (!(lclass & TYPE_COMPOUND)) {
warning(e->pos, "bogus scalar initializer");
@@ -2631,6 +2645,15 @@ static int handle_simple_initializer(struct expression **ep, int nested,
if (!evaluate_expression(e))
return 1;
compatible_assignment_types(e, ctype, ep, "initializer");
+ /*
+ * Initializers for static storage duration objects
+ * shall be constant expressions or a string literal [6.7.8(4)].
+ */
+ if ((ctype->ctype.modifiers & (MOD_TOPLEVEL | MOD_STATIC)) &&
+ !(e->flags & (EXPR_FLAG_ARITH_CONST_EXPR
+ | EXPR_FLAG_ADDR_CONST_EXPR)))
+ warning(e->pos, "initializer for static storage duration object is not a constant expression");
+
return 1;
}
diff --git a/validation/constexpr-init.c b/validation/constexpr-init.c
new file mode 100644
index 0000000..6c412b8
--- /dev/null
+++ b/validation/constexpr-init.c
@@ -0,0 +1,109 @@
+static int a = 1; // OK
+static int b[2] = {1, 1}; // OK
+static void c(void) {}
+
+static int *d = &a; // OK
+static int *e = &b[1]; // OK
+static int *f = b; // OK
+static void (*g)(void) = c; // OK
+static void (*h)(void) = &c; // OK
+static int *i = (int*)0; // OK
+static int *j = d; // KO
+static int *k = (int*)0 + 1; // OK
+
+static int *l = &a + 1; // OK
+static int *m = &b[1] + 1; // OK
+static int *n = b + 1; // OK
+static int *o = d + 1; // KO
+
+static int *p = &*&a; // OK
+static int *q = &*&b[1]; // OK
+static int *r = &*b; // OK
+static int *s = &*d; // KO
+
+static int *t = &*(&a + 1); // OK
+static int *u = &*(&b[1] + 1); // OK
+static int *v = &*(b + 1); // OK
+static int *w = &*(d + 1); // KO
+
+
+struct A {
+ int a;
+ int b[2];
+};
+
+struct B {
+ int c;
+ struct A d;
+};
+
+static struct B x= {1, {1, {1, 1}}}; // OK
+static struct B y= {a, {1, {1, 1}}}; // KO
+static struct B z= {1, {a, {1, 1}}}; // KO
+static struct B aa= {1, {1, {a, 1}}}; // KO
+static struct B ab= {1, {1, {1, a}}}; // KO
+static struct B ac= {.c = 1, .d = {.a = 1, .b = {1, 1}}}; // OK
+static struct B ad= {.c = a, .d = {.a = 1, .b = {1, 1}}}; // KO
+static struct B ae= {.c = 1, .d = {.a = a, .b = {1, 1}}}; // KO
+static struct B af= {.c = 1, .d = {.a = 1, .b = {a, 1}}}; // KO
+static struct B ag= {.c = 1, .d = {.a = 1, .b = {1, a}}}; // KO
+
+static int *ah = &x.d.a; // OK
+static int *ai = &(&x.d)->a; // OK
+static int *aj = x.d.b; // OK
+static int *ak = (&x.d)->b; // OK
+static int *al = &x.d.b[1]; // OK
+static int *am = &(&x.d)->b[1]; // OK
+
+static int an[] = {a, 1}; // KO
+static int ao[] = {1, a}; // KO
+static int ap[] = {[0] = a, [1] = 1}; // KO
+static int aq[] = {[0] = 1, [1] = a}; // KO
+
+static char *ar = "foobar"; // OK
+
+static void as(void) {
+ int a = 0;
+ int b = a; // OK
+}
+
+static void at(void) {
+ int a = 1;
+ static int b = a; // KO
+}
+
+static void au(void) {
+ int a = 1;
+ static int *b = &a; // KO
+}
+
+static void av(void) {
+ static int a = 1;
+ static int *b = &a; // OK
+}
+
+
+/*
+ * check-name: Static storage object initializer constness verification.
+ *
+ * check-error-start
+constexpr-init.c:11:17: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:17:19: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:22:19: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:27:22: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:41:21: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:42:25: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:43:30: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:44:33: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:46:27: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:47:41: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:48:50: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:49:53: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:58:20: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:59:23: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:60:26: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:61:35: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:72:24: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:77:26: warning: initializer for static storage duration object is not a constant expression
+ * check-error-end
+ */
--
2.4.5
--
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