From: Jim Blandy <jimb@codesourcery.com>
Date: Sat, 4 May 2002 00:21:09 +0000 (+0000)
Subject: * stabsread.c (cleanup_undefined_types): Use replace_type, not memcpy.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=13a393b0d3bc047b7ce69cb25502437d96e8fb95;p=binutils-gdb.git

* stabsread.c (cleanup_undefined_types): Use replace_type, not memcpy.
(read_type): Doc fix.
* gdbtypes.c (replace_type): Doc fix.
---

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 4e8de26967d..d7582011ab5 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,9 @@
 2002-05-03  Jim Blandy  <jimb@redhat.com>
 
+	* stabsread.c (cleanup_undefined_types): Use replace_type, not memcpy.
+	(read_type): Doc fix.
+	* gdbtypes.c (replace_type): Doc fix.
+
 	* stabsread.c (multiply_defined_struct): New complaint.
 	(read_struct_type): If the type we were passed isn't empty, or
 	incomplete, don't read the new struct type into it; complain,
diff --git a/gdb/gdbtypes.c b/gdb/gdbtypes.c
index fa01f36c50d..9132c40b5fe 100644
--- a/gdb/gdbtypes.c
+++ b/gdb/gdbtypes.c
@@ -521,10 +521,10 @@ finish_cv_type (struct type *type)
 
 /* Replace the contents of ntype with the type *type.
 
-   This function should not be necessary, but is due to quirks in the stabs
-   reader.  This should go away.  It does not handle the replacement type
-   being cv-qualified; it could be easily fixed to, but it should go away,
-   remember?  */
+   When building recursive types, it is necessary to update a type's
+   definition after people already have references to it.  The C
+   language's concept of an `incomplete type' is an acknowledgement of
+   this.  */
 void
 replace_type (struct type *ntype, struct type *type)
 {
diff --git a/gdb/stabsread.c b/gdb/stabsread.c
index 74a873eb261..7065b7bbd1a 100644
--- a/gdb/stabsread.c
+++ b/gdb/stabsread.c
@@ -2537,7 +2537,24 @@ again:
 	       the related problems with unnecessarily stubbed types;
 	       someone motivated should attempt to clean up the issue
 	       here as well.  Once a type pointed to has been created it
-	       should not be modified.  */
+	       should not be modified.
+
+               Well, it's not *absolutely* wrong.  Constructing recursive
+               types (trees, linked lists) necessarily entails modifying
+               types after creating them.  Constructing any loop structure
+               entails side effects.  The Dwarf 2 reader does handle this
+               more gracefully (it never constructs more than once
+               instance of a type object, so it doesn't have to copy type
+               objects wholesale), but it still mutates type objects after
+               other folks have references to them.
+
+               Keep in mind that this circularity/mutation issue shows up
+               at the source language level, too: C's "incomplete types",
+               for example.  So the proper cleanup, I think, would be to
+               limit GDB's type smashing to match exactly those required
+               by the source language.  So GDB could have a
+               "complete_this_type" function, but never create unnecessary
+               copies of a type otherwise.  */
 	    replace_type (type, xtype);
 	    TYPE_NAME (type) = NULL;
 	    TYPE_TAG_NAME (type) = NULL;
@@ -5122,10 +5139,7 @@ cleanup_undefined_types (void)
 			    && (TYPE_CODE (SYMBOL_TYPE (sym)) ==
 				TYPE_CODE (*type))
 			    && STREQ (SYMBOL_NAME (sym), typename))
-			  {
-			    memcpy (*type, SYMBOL_TYPE (sym),
-				    sizeof (struct type));
-			  }
+                          replace_type (*type, SYMBOL_TYPE (sym));
 		      }
 		  }
 	      }