[gcc/devel/c++-coroutines] tree-inline: Fix VLA handling [PR95552]

[Iain D Sandoe]

https://gcc.gnu.org/g:77103685ff4b50b3c4d7ee76688bdf452acc82c7

commit 77103685ff4b50b3c4d7ee76688bdf452acc82c7
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Jun 5 16:36:27 2020 -0400

    tree-inline: Fix VLA handling [PR95552]
    
    The problem in this testcase comes from cloning the constructor into
    complete and base variants.  When we clone the body the first time,
    walk_tree_1 calls copy_tree_body_r on the type of the artificial TYPE_DECL
    we made for the VLA type without calling it on the decl itself, so we
    overwrite the type of the TYPE_DECL without copying the decl first.
    
    This has been broken since we started inserting a TYPE_DECL for anonymous
    VLAs in r7-457.
    
    This patch fixes walk_tree_1 to call the function on the TYPE_DECL, as we do
    for other decls of a DECL_EXPR.
    
    gcc/ChangeLog:
    
            PR c++/95552
            * tree.c (walk_tree_1): Call func on the TYPE_DECL of a DECL_EXPR.
    
    gcc/testsuite/ChangeLog:
    
            PR c++/95552
            * g++.dg/ext/vla23.C: New test.

Diff:
---
 gcc/testsuite/g++.dg/ext/vla23.C | 14 ++++++++++++++
 gcc/tree.c                       |  6 ++++++
 2 files changed, 20 insertions(+)

diff --git a/gcc/testsuite/g++.dg/ext/vla23.C b/gcc/testsuite/g++.dg/ext/vla23.C
new file mode 100644
index 00000000000..317a824b2f3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/vla23.C
@@ -0,0 +1,14 @@
+// PR c++/95552
+// Test for VLA and cloned constructor.
+// { dg-additional-options -Wno-vla }
+// { dg-require-effective-target alloca }
+
+struct VB { };
+struct ViewDom: virtual VB
+{
+  ViewDom(int i) { char (*a)[i]; }
+};
+void element( )
+{
+  ViewDom a(2);
+}
diff --git a/gcc/tree.c b/gcc/tree.c
index 7197b4720ce..805f669a945 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -12212,6 +12212,12 @@ walk_tree_1 (tree *tp, walk_tree_fn func, void *data,
 	 Note that DECLs get walked as part of processing the BIND_EXPR.  */
       if (TREE_CODE (DECL_EXPR_DECL (*tp)) == TYPE_DECL)
 	{
+	  /* Call the function for the decl so e.g. copy_tree_body_r can
+	     replace it with the remapped one.  */
+	  result = (*func) (&DECL_EXPR_DECL (*tp), &walk_subtrees, data);
+	  if (result || !walk_subtrees)
+	    return result;
+
 	  tree *type_p = &TREE_TYPE (DECL_EXPR_DECL (*tp));
 	  if (TREE_CODE (*type_p) == ERROR_MARK)
 	    return NULL_TREE;