typeck.c (build_c_cast): Don't decay arrays and functions to pointer type when converting to a class type.

	* typeck.c (build_c_cast): Don't decay arrays and functions to
	pointer type when converting to a class type.

From-SVN: r19659

3 files changed, 58 insertions, 10 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 95eb36e..315feea 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+Sun May 10 23:43:13 1998  Mark Mitchell  <mmitchell@usa.net>
+
+	* typeck.c (build_c_cast): Don't decay arrays and functions to
+	pointer type when converting to a class type.
+
 Sun May 10 22:53:56 1998  Jason Merrill  <jason@yorick.cygnus.com>
 
 	* cp-tree.h (DECL_NAMESPACE_SCOPE): New macro.
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 6c1a1a6..fe66a3b 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -5633,16 +5633,36 @@ build_c_cast (type, expr)
 
       /* Convert functions and arrays to pointers and
 	 convert references to their expanded types,
-	 but don't convert any other types.  */
-      if (TREE_CODE (TREE_TYPE (value)) == FUNCTION_TYPE
-	  || (TREE_CODE (TREE_TYPE (value)) == METHOD_TYPE
-	      /* Don't do the default conversion if we want a
-		 pointer to a function.  */
-	      && ! (TREE_CODE (type) == POINTER_TYPE
-		    && TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE))
-	  || TREE_CODE (TREE_TYPE (value)) == ARRAY_TYPE
-	  || TREE_CODE (TREE_TYPE (value)) == REFERENCE_TYPE)
-	value = default_conversion (value);
+	 but don't convert any other types.  If, however, we are
+	 casting to a class type, there's no reason to do this: the
+	 cast will only succeed if there is a converting constructor,
+	 and the default conversions will be done at that point.  In
+	 fact, doing the default conversion here is actually harmful
+	 in cases like this:
+
+	     typedef int A[2];
+             struct S { S(const A&); };
+
+         since we don't want the array-to-pointer conversion done.  */
+      if (!IS_AGGR_TYPE (type))
+	{
+	  if (TREE_CODE (TREE_TYPE (value)) == FUNCTION_TYPE
+	      || (TREE_CODE (TREE_TYPE (value)) == METHOD_TYPE
+		  /* Don't do the default conversion if we want a
+		     pointer to a function.  */
+		  && ! (TREE_CODE (type) == POINTER_TYPE
+			&& TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE))
+	      || TREE_CODE (TREE_TYPE (value)) == ARRAY_TYPE
+	      || TREE_CODE (TREE_TYPE (value)) == REFERENCE_TYPE)
+	  value = default_conversion (value);
+	}
+      else if (TREE_CODE (TREE_TYPE (value)) == REFERENCE_TYPE)
+	/* However, even for class types, we still need to strip away
+	   the reference type, since the call to convert_force below
+	   does not expect the input expression to be of reference
+	   type.  */
+	value = convert_from_reference (value);
+	
       otype = TREE_TYPE (value);
 
       /* Optionally warn about potentially worrisome casts.  */
diff --git a/gcc/testsuite/g++.old-deja/g++.other/cvt1.C b/gcc/testsuite/g++.old-deja/g++.other/cvt1.C
new file mode 100644
index 0000000..f448cc1a
--- /dev/null
+++ b/gcc/testsuite/g++.old-deja/g++.other/cvt1.C
@@ -0,0 +1,23 @@
+// Build don't link:
+
+typedef int Array_T[2];
+
+struct S1 {
+  S1(const Array_T&);
+};
+
+struct S2 {
+  S1 g();
+  Array_T a;
+};
+
+S1 S2::g()
+{
+  return S1(a);
+}
+
+void h()
+{
+  S2 s2;
+  s2.g();
+}