2002-08-24 Matt Austern <austern@apple.com>

        * tree.c (lvalue_p_1): Add argument for whether casts of lvalues
        are allowable.
        (real_lvalue_p): Update caller.
        (lvalue_p): Ditto.
        (non_cast_lvalue_or_else): New.
        * tree.h: Declare it.
        * typeck.c (build_unary_op): Use non_cast_lvalue_or_else.

2002-08-24  Matt Austern  <austern@apple.com>

        * g++.dg/ext/lvaddr.C: New test.
        * g++.dg/ext/lvcast.C: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@56560 138bc75d-0d04-0410-961f-82ee72b054a4

7 files changed, 85 insertions, 17 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index cb95b6d33b7..def395ea126 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,13 @@
+2002-08-24  Matt Austern  <austern@apple.com>
+
+	* tree.c (lvalue_p_1): Add argument for whether casts of lvalues
+	are allowable.
+	(real_lvalue_p): Update caller.
+	(lvalue_p): Ditto.
+	(non_cast_lvalue_or_else): New.
+	* tree.h: Declare it.
+        * typeck.c (build_unary_op): Use non_cast_lvalue_or_else.
+
 2002-08-22  Mark Mitchell  <mark@codesourcery.com>
 
 	* typeck.c (build_class_member_access_expr): Handle COMPOUND_EXPR
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 44a52fc8e78..ef4f171829b 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -4184,6 +4184,7 @@ extern tree canonical_type_variant              PARAMS ((tree));
 extern void unshare_base_binfos			PARAMS ((tree));
 extern int member_p				PARAMS ((tree));
 extern cp_lvalue_kind real_lvalue_p		PARAMS ((tree));
+extern int non_cast_lvalue_or_else		PARAMS ((tree, const char *));
 extern tree build_min				PARAMS ((enum tree_code, tree,
 							 ...));
 extern tree build_min_nt			PARAMS ((enum tree_code, ...));
diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
index 36305660372..6e092850762 100644
--- a/gcc/cp/tree.c
+++ b/gcc/cp/tree.c
@@ -39,7 +39,7 @@ static tree build_cplus_array_type_1 PARAMS ((tree, tree));
 static int list_hash_eq PARAMS ((const void *, const void *));
 static hashval_t list_hash_pieces PARAMS ((tree, tree, tree));
 static hashval_t list_hash PARAMS ((const void *));
-static cp_lvalue_kind lvalue_p_1 PARAMS ((tree, int));
+static cp_lvalue_kind lvalue_p_1 PARAMS ((tree, int, int));
 static tree no_linkage_helper PARAMS ((tree *, int *, void *));
 static tree build_srcloc PARAMS ((const char *, int));
 static tree mark_local_for_remap_r PARAMS ((tree *, int *, void *));
@@ -59,9 +59,10 @@ static tree handle_init_priority_attribute PARAMS ((tree *, tree, tree, int, boo
    non-zero, rvalues of class type are considered lvalues.  */
 
 static cp_lvalue_kind
-lvalue_p_1 (ref, treat_class_rvalues_as_lvalues)
+lvalue_p_1 (ref, treat_class_rvalues_as_lvalues, allow_cast_as_lvalue)
      tree ref;
      int treat_class_rvalues_as_lvalues;
+     int allow_cast_as_lvalue;
 {
   cp_lvalue_kind op1_lvalue_kind = clk_none;
   cp_lvalue_kind op2_lvalue_kind = clk_none;
@@ -84,16 +85,28 @@ lvalue_p_1 (ref, treat_class_rvalues_as_lvalues)
     case WITH_CLEANUP_EXPR:
     case REALPART_EXPR:
     case IMAGPART_EXPR:
-      /* This shouldn't be here, but there are lots of places in the compiler
-         that are sloppy about tacking on NOP_EXPRs to the same type when
-	 no actual conversion is happening.  */
-    case NOP_EXPR:
       return lvalue_p_1 (TREE_OPERAND (ref, 0),
-			 treat_class_rvalues_as_lvalues);
+			 treat_class_rvalues_as_lvalues,
+			 allow_cast_as_lvalue);
+
+    case NOP_EXPR:
+      /* If expression doesn't change the type, we consider it as an
+	 lvalue even when cast_as_lvalue extension isn't selected.
+	 That's because parts of the compiler are alleged to be sloppy
+	 about sticking in NOP_EXPR node for no good reason. */
+      if (allow_cast_as_lvalue ||
+	  same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (ref)),
+		       TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (ref, 0)))))
+	return lvalue_p_1 (TREE_OPERAND (ref, 0),
+			   treat_class_rvalues_as_lvalues,
+			   allow_cast_as_lvalue);
+      else
+	return clk_none;
 
     case COMPONENT_REF:
       op1_lvalue_kind = lvalue_p_1 (TREE_OPERAND (ref, 0),
-				    treat_class_rvalues_as_lvalues);
+				    treat_class_rvalues_as_lvalues,
+				    allow_cast_as_lvalue);
       if (op1_lvalue_kind 
 	  /* The "field" can be a FUNCTION_DECL or an OVERLOAD in some
 	     situations.  */
@@ -134,16 +147,20 @@ lvalue_p_1 (ref, treat_class_rvalues_as_lvalues)
     case MAX_EXPR:
     case MIN_EXPR:
       op1_lvalue_kind = lvalue_p_1 (TREE_OPERAND (ref, 0),
-				    treat_class_rvalues_as_lvalues);
+				    treat_class_rvalues_as_lvalues,
+				    allow_cast_as_lvalue);
       op2_lvalue_kind = lvalue_p_1 (TREE_OPERAND (ref, 1),
-				    treat_class_rvalues_as_lvalues);
+				    treat_class_rvalues_as_lvalues,
+				    allow_cast_as_lvalue);
       break;
 
     case COND_EXPR:
       op1_lvalue_kind = lvalue_p_1 (TREE_OPERAND (ref, 1),
-				    treat_class_rvalues_as_lvalues);
+				    treat_class_rvalues_as_lvalues,
+				    allow_cast_as_lvalue);
       op2_lvalue_kind = lvalue_p_1 (TREE_OPERAND (ref, 2),
-				    treat_class_rvalues_as_lvalues);
+				    treat_class_rvalues_as_lvalues,
+				    allow_cast_as_lvalue);
       break;
 
     case MODIFY_EXPR:
@@ -151,7 +168,8 @@ lvalue_p_1 (ref, treat_class_rvalues_as_lvalues)
 
     case COMPOUND_EXPR:
       return lvalue_p_1 (TREE_OPERAND (ref, 1),
-			 treat_class_rvalues_as_lvalues);
+			 treat_class_rvalues_as_lvalues,
+			 allow_cast_as_lvalue);
 
     case TARGET_EXPR:
       return treat_class_rvalues_as_lvalues ? clk_class : clk_none;
@@ -196,7 +214,7 @@ cp_lvalue_kind
 real_lvalue_p (ref)
      tree ref;
 {
-  return lvalue_p_1 (ref, /*treat_class_rvalues_as_lvalues=*/0);
+  return lvalue_p_1 (ref, /*treat_class_rvalues_as_lvalues=*/ 0, /*cast*/ 1);
 }
 
 /* This differs from real_lvalue_p in that class rvalues are
@@ -207,7 +225,7 @@ lvalue_p (ref)
      tree ref;
 {
   return 
-    (lvalue_p_1 (ref, /*treat_class_rvalues_as_lvalues=*/1) != clk_none);
+    (lvalue_p_1 (ref, /*class rvalue ok*/ 1, /*cast*/ 1) != clk_none);
 }
 
 /* Return nonzero if REF is an lvalue valid for this language;
@@ -218,7 +236,20 @@ lvalue_or_else (ref, string)
      tree ref;
      const char *string;
 {
-  int win = lvalue_p (ref);
+  int ret = lvalue_p_1 (ref, /* class rvalue ok */ 1, /* cast ok */ 1);
+  int win = (ret != clk_none);
+  if (! win)
+    error ("non-lvalue in %s", string);
+  return win;
+}
+
+int
+non_cast_lvalue_or_else (ref, string)
+     tree ref;
+     const char *string;
+{
+  int ret = lvalue_p_1 (ref, /* class rvalue ok */ 1, /* cast ok */ 0);
+  int win = (ret != clk_none);
   if (! win)
     error ("non-lvalue in %s", string);
   return win;
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 624b379cf71..8535cde4ae7 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -4268,7 +4268,7 @@ build_unary_op (code, xarg, noconvert)
 	 is an error.  */
       else if (TREE_CODE (argtype) != FUNCTION_TYPE
 	       && TREE_CODE (argtype) != METHOD_TYPE
-	       && !lvalue_or_else (arg, "unary `&'"))
+	       && !non_cast_lvalue_or_else (arg, "unary `&'"))
 	return error_mark_node;
 
       if (argtype != error_mark_node)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 00a92134d45..f509299f6e5 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2002-08-24  Matt Austern  <austern@apple.com>
+
+	* g++.dg/ext/lvaddr.C: New test.
+	* g++.dg/ext/lvcast.C: New test.
+	
 2002-08-22  Mark Mitchell  <mark@codesourcery.com>
 
 	* testsuite/g++.dg/inherit/cond1.C: New test.
diff --git a/gcc/testsuite/g++.dg/ext/lvaddr.C b/gcc/testsuite/g++.dg/ext/lvaddr.C
new file mode 100644
index 00000000000..184afce900b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/lvaddr.C
@@ -0,0 +1,10 @@
+// Copyright (C) 2002 Free Software Foundation
+// Contributed by Matt Austern <austern@apple.com>
+
+// { dg-do compile }
+
+void f()
+{
+  int n;
+  char* p = &(char) n;		// { dg-error "non-lvalue" }
+}
diff --git a/gcc/testsuite/g++.dg/ext/lvcast.C b/gcc/testsuite/g++.dg/ext/lvcast.C
new file mode 100644
index 00000000000..efff04ec089
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/lvcast.C
@@ -0,0 +1,11 @@
+// Copyright (C) 2002 Free Software Foundation
+// Contributed by Matt Austern <austern@apple.com>
+
+// { dg-do compile }
+// { dg-options -fpermissive }
+
+void f ()
+{
+  int n;
+  (char) n = 1;
+}