On 9/7/23 11:23, Marek Polacek wrote:
On Tue, Sep 05, 2023 at 04:36:34PM -0400, Jason Merrill wrote:
On 9/5/23 15:59, Marek Polacek wrote:
On Tue, Sep 05, 2023 at 10:52:04AM -0400, Jason Merrill wrote:
On 9/1/23 13:23, Marek Polacek wrote:
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
In the review of P2564:
<https://gcc.gnu.org/pipermail/gcc-patches/2023-August/628747.html>
it turned out that in order to correctly handle an example in the paper,
we should stop doing immediate evaluation in build_over_call and
bot_replace, and instead do it in cp_fold_r. This patch does that.
Another benefit is that this is a pretty significant simplification, at
least in my opinion. Also, this fixes the c++/110997 ICE (but the test
doesn't compile yet).
The main drawback seems to be that cp_fold_r doesn't process as much
code as we did before: uninstantiated templates
That's acceptable, it's an optional diagnostic.
and things like "false ? foo () : 1".
This is a problem. Maybe we want cp_fold_r to recurse into the arms of a
COND_EXPR before folding them away? Maybe only if we know we've seen an
immediate function?
Unfortunately we had already thrown the dead branch away when we got to
cp_fold_r. I wonder if we have to adjust cxx_eval_conditional_expression
to call cp_fold_r on the dead branch too,
Hmm, I guess so.
perhaps with a new ff_ flag to skip the whole second switch in cp_fold_r?
Or factor out the immediate function handling to a separate walk function
that cp_fold_r also calls?
I did that.
But then it's possible that the in_immediate_context checks have to stay.
We can just not do the walk in immediate (or mce_true) context, like we
currently avoid calling cp_fold_function.
Right. Unfortunately I have to check even when mce_true, consider
consteval int bar (int i) { if (i != 1) throw 1; return 0; }
constexpr int a = 0 ? bar(3) : 3;
I disagree; the call is in a manifestly constant-evaluated expression,
and so is now considered an immediate function context, and we should
accept that example.
For mce_unknown I guess we'd want
to set *non_constant_p instead of giving an error.
I did not do this because I haven't found a case where it would make
a difference.
I think it will given the above comment.
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 0ca4370deab..397d5c7ec3f 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -2311,6 +2311,29 @@ cxx_dynamic_cast_fn_p (tree fndecl)
&& CP_DECL_CONTEXT (fndecl) == abi_node);
}
+/* Return true if we are in the body of a consteval function. > + This is in addition to in_immediate_context because that
+ uses current_function_decl which may not be available. CTX is
+ the current constexpr context. */
+
+static bool
+in_immediate_context (const constexpr_ctx *ctx)
+{
+ if (in_immediate_context ())
+ return true;
Can't we check for mce_true here instead of looking at the call chain?
+/* A wrapper around cp_fold_immediate_r. */
+
+void
+cp_fold_immediate (tree *tp)
+{
Maybe return early if consteval isn't supported in the active standard?
Jason
