Here, we capture nf, then the use of the proxy decays to a constant during
semantic processing of +nf. Since we saw some decay from proxy to constant,
we walk through the lambda body to see which proxies are still used, but we
weren't walking into subtrees of DECL_EXPR at all, so we missed the use of
&nf in the initializer of y, and removed the capture. But then at
instantiation time we try to use nf, don't have a proxy anymore, and ICE.
Currently the template representation of +nf still uses the proxy rather than
the decayed constant; I will address that in a follow-up patch.
Tested x86_64-pc-linux-gnu, applying to trunk.
* lambda.c (mark_const_cap_r): Do walk subtrees of DECL_EXPR for
non-proxy decls.
---
gcc/cp/lambda.c | 6 ++++--
.../g++.dg/cpp1y/lambda-generic-const6.C | 18 ++++++++++++++++++
gcc/cp/ChangeLog | 6 ++++++
3 files changed, 28 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/lambda-generic-const6.C
diff --git a/gcc/cp/lambda.c b/gcc/cp/lambda.c
index 4b7a358a0ad..c31b06e2b1e 100644
--- a/gcc/cp/lambda.c
+++ b/gcc/cp/lambda.c
@@ -1488,8 +1488,10 @@ mark_const_cap_r (tree *t, int *walk_subtrees, void
*data)
{
tree decl = DECL_EXPR_DECL (*t);
if (is_constant_capture_proxy (decl))
- var = DECL_CAPTURED_VARIABLE (decl);
- *walk_subtrees = 0;
+ {
+ var = DECL_CAPTURED_VARIABLE (decl);
+ *walk_subtrees = 0;
+ }
}
else if (is_constant_capture_proxy (*t))
var = DECL_CAPTURED_VARIABLE (*t);
diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-generic-const6.C
b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-const6.C
new file mode 100644
index 00000000000..e85d6497488
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-generic-const6.C
@@ -0,0 +1,18 @@
+// PR c++/88761
+// { dg-do compile { target c++14 } }
+
+template <class T>
+void f(T t) { t(1); }
+
+int main()
+{
+ const unsigned long nf = 10'000'000;
+
+ auto loop = [&](auto)
+ {
+ auto x = +nf;
+ auto y = &nf;
+ };
+
+ f(loop);
+}
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index f0545aee116..6c474fdda16 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2019-02-01 Jason Merrill <ja...@redhat.com>
+
+ PR c++/88761 - ICE with reference capture of constant.
+ * lambda.c (mark_const_cap_r): Do walk subtrees of DECL_EXPR for
+ non-proxy decls.
+
2019-02-01 Marek Polacek <pola...@redhat.com>
PR c++/88325 - ICE with invalid out-of-line template member definition.
base-commit: 5f6f6e51c0ff7f6e9e26f026e8ea856e0c4b91b5
--
2.20.1
