On 11/23/23 03:32, Jakub Jelinek wrote:
On Wed, Nov 22, 2023 at 04:53:48PM -0500, Jason Merrill wrote:
I agree it's weird to get two of the same error, but maybe instead of
duplicating the error, we could look up data only if size succeeded, and
then error once if either failed?
Here is what I've committed after another bootstrap/regtest on x86_64-linux
and i686-linux. Besides the above requested change I've tweaked 2 lines
in the test not to rely on a particular std::size_t exact type because
otherwise the test failed on i686-linux. And accepting there only the
current
unsigned int
long unsigned int
long long unsinged int
unsigned __int20__ (or how exactly is this one spelled in diagnostics)
seems fragile.
--- gcc/cp/semantics.cc.jj 2023-11-22 11:30:08.019325101 +0100
+++ gcc/cp/semantics.cc 2023-11-22 22:58:25.194480633 +0100
@@ -11485,9 +11534,89 @@ finish_static_assert (tree condition, tr
if (processing_template_decl)
goto defer;
- int sz = TREE_INT_CST_LOW (TYPE_SIZE_UNIT
- (TREE_TYPE (TREE_TYPE (message))));
- int len = TREE_STRING_LENGTH (message) / sz - 1;
+ int len;
+ const char *msg = NULL;
+ char *buf = NULL;
+ if (message_sz && message_data)
+ {
+ tree msz = cxx_constant_value (message_sz, NULL_TREE, complain);
+ if (!tree_fits_uhwi_p (msz))
+ {
+ error_at (location,
+ "%<static_assert%> message %<size()%> "
+ "must be a constant expression");
+ return;
+ }
+ else if ((unsigned HOST_WIDE_INT) (int) tree_to_uhwi (msz)
+ != tree_to_uhwi (msz))
+ {
+ error_at (location,
+ "%<static_assert%> message %<size()%> "
+ "%qE too large", msz);
+ return;
+ }
+ len = tree_to_uhwi (msz);
+ tree data = maybe_constant_value (message_data, NULL_TREE,
+ mce_true);
+ if (!reduced_constant_expression_p (data))
+ data = NULL_TREE;
+ if (len)
+ {
+ if (data)
+ msg = c_getstr (data);
+ if (msg == NULL)
+ buf = XNEWVEC (char, len);
Jonathan pointed out elsewhere that this gets leaked if error return
prevents us from getting to the XDELETEVEC.
+ for (int i = 0; i < len; ++i)
+ {
+ tree t = message_data;
+ if (i)
+ t = build2 (POINTER_PLUS_EXPR,
+ TREE_TYPE (message_data), message_data,
+ size_int (i));
+ t = build1 (INDIRECT_REF, TREE_TYPE (TREE_TYPE (t)), t);
+ tree t2 = cxx_constant_value (t, NULL_TREE, complain);
+ if (!tree_fits_shwi_p (t2))
+ {
+ error_at (location,
+ "%<static_assert%> message %<data()[%d]%> "
+ "must be a constant expression", i);
+ return;
+ }
+ if (msg == NULL)
+ buf[i] = tree_to_shwi (t2);
+ /* If c_getstr worked, just verify the first and
+ last characters using constant evaluation. */
+ else if (len > 2 && i == 0)
+ i = len - 2;
+ }
+ if (msg == NULL)
+ msg = buf;
+ }
+ else if (!data)
+ {
+ /* We don't have any function to test whether some
+ expression is a core constant expression. So, instead
+ test whether (message.data (), 0) is a constant
+ expression. */
+ data = build2 (COMPOUND_EXPR, integer_type_node,
+ message_data, integer_zero_node);
+ tree t = cxx_constant_value (data, NULL_TREE, complain);
+ if (!integer_zerop (t))
+ {
+ error_at (location,
+ "%<static_assert%> message %<data()%> "
+ "must be a core constant expression");
+ return;
+ }
+ }
+ }
+ else
+ {
+ tree eltype = TREE_TYPE (TREE_TYPE (message));
+ int sz = TREE_INT_CST_LOW (TYPE_SIZE_UNIT (eltype));
+ msg = TREE_STRING_POINTER (message);
+ len = TREE_STRING_LENGTH (message) / sz - 1;
+ }
/* See if we can find which clause was failing (for logical AND). */
tree bad = find_failing_clause (NULL, orig_condition);
@@ -11497,12 +11626,13 @@ finish_static_assert (tree condition, tr
auto_diagnostic_group d;
- /* Report the error. */
+ /* Report the error. */
if (len == 0)
error_at (cloc, "static assertion failed");
else
- error_at (cloc, "static assertion failed: %s",
- TREE_STRING_POINTER (message));
+ error_at (cloc, "static assertion failed: %.*s", len, msg);
+
+ XDELETEVEC (buf);
diagnose_failing_condition (bad, cloc, show_expr_p);
}
