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C++ PATCH to fix ICE in replace_placeholders_r (PR c++/79937)
- From: Marek Polacek <polacek at redhat dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>, Jason Merrill <jason at redhat dot com>
- Date: Tue, 7 Mar 2017 18:10:48 +0100
- Subject: C++ PATCH to fix ICE in replace_placeholders_r (PR c++/79937)
- Authentication-results: sourceware.org; auth=none
In this testcase we have
C c = bar (X{1});
which store_init_value sees as
c = TARGET_EXPR <D.2332, bar (TARGET_EXPR <D.2298, {.i=1, .n=(&<PLACEHOLDER_EXPR struct X>)->i}>)>
i.e. we're initializing "c" with a TARGET_EXPR. We call replace_placeholders
that walks the whole tree to substitute the placeholders. Eventually we find
the nested <PLACEHOLDER_EXPR struct X> but that's for another object, so we
crash. Seems that we shouldn't have stepped into the second TARGET_EXPR at
all; it has nothing to with "c", it's bar's argument.
It occurred to me that we shouldn't step into CALL_EXPRs and leave the
placeholders in function arguments to cp_gimplify_init_expr which calls
replace_placeholders for constructors. Not sure if it's enough to handle
CALL_EXPRs like this, anything else?
Bootstrapped/regtested on x86_64-linux, ok for trunk and 6?
2017-03-07 Marek Polacek <polacek@redhat.com>
PR c++/79937 - ICE in replace_placeholders_r
* tree.c (replace_placeholders_r): Don't walk into CALL_EXPRs.
* g++.dg/cpp1y/nsdmi-aggr7.C: New test.
diff --git gcc/cp/tree.c gcc/cp/tree.c
index d3c63b8..6a4f065 100644
--- gcc/cp/tree.c
+++ gcc/cp/tree.c
@@ -2751,6 +2751,11 @@ replace_placeholders_r (tree* t, int* walk_subtrees, void* data_)
switch (TREE_CODE (*t))
{
+ case CALL_EXPR:
+ /* Don't mess with placeholders in an unrelated object. */
+ *walk_subtrees = false;
+ break;
+
case PLACEHOLDER_EXPR:
{
tree x = obj;
diff --git gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr7.C gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr7.C
index e69de29..c2fd404 100644
--- gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr7.C
+++ gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr7.C
@@ -0,0 +1,21 @@
+// PR c++/79937
+// { dg-do compile { target c++14 } }
+
+struct C {};
+
+struct X {
+ unsigned i;
+ unsigned n = i;
+};
+
+C
+bar (X)
+{
+ return {};
+}
+
+void
+foo ()
+{
+ C c = bar (X{1});
+}
Marek