# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1489165027 -3600
# Node ID 6b790fb0924e93dc7d46161e83a066075deb8a38
# Parent  85416087aa62d23e139ed11ed8d871eafbb4eeb6
Uphold positioning conflicts only if the existing locations were explicitly
specified. Otherwise, reposition attributes, causing the program to be
regenerated, if it was only previously-generated attribute position data being
used when a conflict occurred.

diff -r 85416087aa62 -r 6b790fb0924e optimiser.py
--- a/optimiser.py	Fri Mar 10 17:26:58 2017 +0100
+++ b/optimiser.py	Fri Mar 10 17:57:07 2017 +0100
@@ -435,8 +435,22 @@
                 attrnames = filter(lambda x: not x.startswith("$t"), attrnames)
                 self.all_attrs[(objkind, name)] = attrnames
 
-        self.locations = get_allocated_locations(self.all_attrs,
-            get_attributes_and_sizes, self.existing_locations)
+        try:
+            self.locations = get_allocated_locations(self.all_attrs,
+                get_attributes_and_sizes, self.existing_locations)
+
+        # Uphold positioning conflicts only if the existing locations were
+        # explicitly specified.
+
+        except OptimiseError:
+            if self.locations_filename:
+                raise
+
+            # Otherwise, reposition attributes, causing the program to be
+            # regenerated.
+
+            self.locations = get_allocated_locations(self.all_attrs,
+                get_attributes_and_sizes)
 
     def populate_parameters(self):