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* [gcc r10-9844] c++: constexpr if and nested generic lambda [PR99201]
@ 2021-05-20 21:34 Jason Merrill
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From: Jason Merrill @ 2021-05-20 21:34 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:7c365bb1462a7a9dadf9b8f8668a0c832b18056c
commit r10-9844-g7c365bb1462a7a9dadf9b8f8668a0c832b18056c
Author: Jason Merrill <jason@redhat.com>
Date: Sun Apr 4 01:01:56 2021 -0400
c++: constexpr if and nested generic lambda [PR99201]
When building up *_EXTRA_ARGS for a constexpr if or pack expansion, we need
to walk into the body of a lambda to find all the local_specializations that
we need to remember, like we do in find_parameter_packs_r.
gcc/cp/ChangeLog:
PR c++/99201
* pt.c (class el_data): Add visited field.
(extract_local_specs): Pass it to cp_walk_tree.
(extract_locals_r): Walk into the body of a lambda.
gcc/testsuite/ChangeLog:
PR c++/99201
* g++.dg/cpp1z/constexpr-if-lambda4.C: New test.
Diff:
---
gcc/cp/pt.c | 15 ++++++++++++++-
gcc/testsuite/g++.dg/cpp1z/constexpr-if-lambda4.C | 22 ++++++++++++++++++++++
2 files changed, 36 insertions(+), 1 deletion(-)
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 8616118228c..986c8207a49 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -12672,7 +12672,11 @@ tsubst_binary_right_fold (tree t, tree args, tsubst_flags_t complain,
class el_data
{
public:
+ /* Set of variables declared within the pattern. */
hash_set<tree> internal;
+ /* Set of AST nodes that have been visited by the traversal. */
+ hash_set<tree> visited;
+ /* List of local_specializations used within the pattern. */
tree extra;
tsubst_flags_t complain;
@@ -12712,6 +12716,15 @@ extract_locals_r (tree *tp, int */*walk_subtrees*/, void *data_)
}
}
}
+ else if (TREE_CODE (*tp) == LAMBDA_EXPR)
+ {
+ /* Since we defer implicit capture, look in the parms and body. */
+ tree fn = lambda_function (*tp);
+ cp_walk_tree (&TREE_TYPE (fn), &extract_locals_r, &data,
+ &data.visited);
+ cp_walk_tree (&DECL_SAVED_TREE (fn), &extract_locals_r, &data,
+ &data.visited);
+ }
else if (tree spec = retrieve_local_specialization (*tp))
{
if (data.internal.contains (*tp))
@@ -12768,7 +12781,7 @@ static tree
extract_local_specs (tree pattern, tsubst_flags_t complain)
{
el_data data (complain);
- cp_walk_tree_without_duplicates (&pattern, extract_locals_r, &data);
+ cp_walk_tree (&pattern, extract_locals_r, &data, &data.visited);
return data.extra;
}
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-if-lambda4.C b/gcc/testsuite/g++.dg/cpp1z/constexpr-if-lambda4.C
new file mode 100644
index 00000000000..99408025629
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-if-lambda4.C
@@ -0,0 +1,22 @@
+// PR c++/99201
+// { dg-do compile { target c++17 } }
+
+template <typename RefF>
+ auto
+ make_tester(const RefF& reffun)
+ {
+ return [=](auto in) {
+ auto&& expected = [&](const auto&... vs) {
+ if constexpr (sizeof(in) > 0)
+ return [&](int i) { return reffun(vs[i]...); }(0);
+ else
+ return [&](int i) { return reffun(vs[i]...); }(0);
+ };
+ };
+ }
+
+int main()
+{
+ make_tester([](int x) { return x; })(0);
+ return 0;
+}
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