Changeset f6cc734e

Timestamp:

Jul 22, 2019, 4:13:38 PM (5 years ago)

Author:

Michael Brooks <mlbrooks@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, master, new-ast, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

4eb43fa

Parents:

99da267

Message:

Fixing new-resolver bug with incorrectly reused FunctionType? pieces in old-model AST after convert-back. (See code comments for detail.) Symptom was crash (with pure virtual method call, due to double delete) during InstantiateGeneric? pass on Bootloader. Now libcfa build progresses to next file, src/prelude.o.

File:

• src/AST/Convert.cpp (modified) (1 diff)

src/AST/Convert.cpp

@@ -607 +607 @@
 
                 tgt->result = get<Type>().accept1(src->result);
+                // Unconditionally use a clone of the result type.
+                // We know this will leak some objects: much of the immediate conversion result.
+                // In some cases, using the conversion result directly gives unintended object sharing.
+                // A parameter (ObjectDecl, a child of a FunctionType) is shared by the weak-ref cache.
+                // But tgt->result must be fully owned privately by tgt.
+                // Applying these conservative copies here means
+                // - weak references point at the declaration's copy, not these expr.result copies (good)
+                // - we copy more objects than really needed (bad, tolerated)
+                if (tgt->result) {
+                        tgt->result = tgt->result->clone();
+                }
                 return visitBaseExpr_skipResultType(src, tgt);
         }