compiler: update iota handling, fix using iota in array length

    
    CL 71750 changed the definition of how iota works.  This patch updates
    gccgo for the new definition.
    
    We've been mishandling iota appearing in a type that appears in a
    const expression, as in `c = len([iota]int{})`.  Correct that by copying
    type expressions when we copy an expression.  For simplicity only copy
    when it can change the size of a type, as that is the only case where
    iota in a type can affect the value of a constant (I think).  This is
    still a bunch of changes, but almost all boilerplate.
    
    Fixes golang/go#22341
    
    Reviewed-on: https://go-review.googlesource.com/91475

From-SVN: r257379

1 files changed, 9 insertions, 70 deletions

diff --git a/gcc/go/gofrontend/expressions.h b/gcc/go/gofrontend/expressions.h
index 18fd91b..d16a284 100644
--- a/gcc/go/gofrontend/expressions.h
+++ b/gcc/go/gofrontend/expressions.h
@@ -1664,11 +1664,7 @@ class Type_conversion_expression : public Expression
   do_check_types(Gogo*);
 
   Expression*
-  do_copy()
-  {
-    return new Type_conversion_expression(this->type_, this->expr_->copy(),
-					  this->location());
-  }
+  do_copy();
 
   Bexpression*
   do_get_backend(Translate_context* context);
@@ -1720,12 +1716,7 @@ class Unsafe_type_conversion_expression : public Expression
   { this->expr_->determine_type_no_context(); }
 
   Expression*
-  do_copy()
-  {
-    return new Unsafe_type_conversion_expression(this->type_,
-						 this->expr_->copy(),
-						 this->location());
-  }
+  do_copy();
 
   Bexpression*
   do_get_backend(Translate_context*);
@@ -3430,19 +3421,7 @@ class Composite_literal_expression : public Parser_expression
   do_lower(Gogo*, Named_object*, Statement_inserter*, int);
 
   Expression*
-  do_copy()
-  {
-    Composite_literal_expression *ret =
-      new Composite_literal_expression(this->type_, this->depth_,
-				       this->has_keys_,
-				       (this->vals_ == NULL
-					? NULL
-					: this->vals_->copy()),
-				       this->all_are_names_,
-				       this->location());
-    ret->key_path_ = this->key_path_;
-    return ret;
-  }
+  do_copy();
 
   void
   do_dump_expression(Ast_dump_context*) const;
@@ -3556,18 +3535,7 @@ class Struct_construction_expression : public Expression,
   do_check_types(Gogo*);
 
   Expression*
-  do_copy()
-  {
-    Struct_construction_expression* ret =
-      new Struct_construction_expression(this->type_,
-					 (this->vals() == NULL
-					  ? NULL
-					  : this->vals()->copy()),
-					 this->location());
-    if (this->traverse_order() != NULL)
-      ret->set_traverse_order(this->traverse_order());
-    return ret;
-  }
+  do_copy();
 
   Expression*
   do_flatten(Gogo*, Named_object*, Statement_inserter*);
@@ -3671,15 +3639,7 @@ class Fixed_array_construction_expression :
 
  protected:
   Expression*
-  do_copy()
-  {
-    return new Fixed_array_construction_expression(this->type(),
-						   this->indexes(),
-						   (this->vals() == NULL
-						    ? NULL
-						    : this->vals()->copy()),
-						   this->location());
-  }
+  do_copy();
 
   Bexpression*
   do_get_backend(Translate_context*);
@@ -3712,14 +3672,7 @@ class Slice_construction_expression : public Array_construction_expression
   do_traverse(Traverse* traverse);
 
   Expression*
-  do_copy()
-  {
-    return new Slice_construction_expression(this->type(), this->indexes(),
-					     (this->vals() == NULL
-					      ? NULL
-					      : this->vals()->copy()),
-					     this->location());
-  }
+  do_copy();
 
   Bexpression*
   do_get_backend(Translate_context*);
@@ -3778,14 +3731,7 @@ class Map_construction_expression : public Expression
   do_check_types(Gogo*);
 
   Expression*
-  do_copy()
-  {
-    return new Map_construction_expression(this->type_,
-					   (this->vals_ == NULL
-					    ? NULL
-					    : this->vals_->copy()),
-					   this->location());
-  }
+  do_copy();
 
   Bexpression*
   do_get_backend(Translate_context*);
@@ -3846,11 +3792,7 @@ class Type_guard_expression : public Expression
   do_check_types(Gogo*);
 
   Expression*
-  do_copy()
-  {
-    return new Type_guard_expression(this->expr_->copy(), this->type_,
-				     this->location());
-  }
+  do_copy();
 
   Bexpression*
   do_get_backend(Translate_context*);
@@ -4102,10 +4044,7 @@ class Backend_expression : public Expression
   { }
 
   Expression*
-  do_copy()
-  {
-    return new Backend_expression(this->bexpr_, this->type_, this->location());
-  }
+  do_copy();
 
   Bexpression*
   do_get_backend(Translate_context*)