[gcc/devel/rust/master] Fix nullptr deref on HIR::Function

[gcc/devel/rust/master] Fix nullptr deref on HIR::Function

[Thomas Schwinge]

https://gcc.gnu.org/g:444bb5b818315d278914df10dc1c5c650bae6946

commit 444bb5b818315d278914df10dc1c5c650bae6946
Author: Philip Herron <philip.herron@embecosm.com>
Date:   Thu Jul 7 11:05:27 2022 +0100

    Fix nullptr deref on HIR::Function
    
    The clone interface on HIR::Functions can have an optional nullptr return
    type which was always being derefed for the clone interface. This seems
    to trigger when compiling with gcc-4.8 but not on modern GCC versions.

Diff:
---
 gcc/rust/hir/tree/rust-hir-item.h | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/gcc/rust/hir/tree/rust-hir-item.h b/gcc/rust/hir/tree/rust-hir-item.h
index 109a5c238f2..1d451867753 100644
--- a/gcc/rust/hir/tree/rust-hir-item.h
+++ b/gcc/rust/hir/tree/rust-hir-item.h
@@ -1111,11 +1111,16 @@ public:
     : VisItem (other), qualifiers (other.qualifiers),
       function_name (other.function_name),
       function_params (other.function_params),
-      return_type (other.return_type->clone_type ()),
       where_clause (other.where_clause),
       function_body (other.function_body->clone_block_expr ()),
       self (other.self), locus (other.locus)
   {
+    // guard to prevent null dereference (always required)
+    if (other.return_type != nullptr)
+      return_type = other.return_type->clone_type ();
+    else
+      return_type = nullptr;
+
     generic_params.reserve (other.generic_params.size ());
     for (const auto &e : other.generic_params)
       generic_params.push_back (e->clone_generic_param ());
@@ -1128,7 +1133,13 @@ public:
     function_name = other.function_name;
     qualifiers = other.qualifiers;
     function_params = other.function_params;
-    return_type = other.return_type->clone_type ();
+
+    // guard to prevent null dereference (always required)
+    if (other.return_type != nullptr)
+      return_type = other.return_type->clone_type ();
+    else
+      return_type = nullptr;
+
     where_clause = other.where_clause;
     function_body = other.function_body->clone_block_expr ();
     locus = other.locus;