Purge ATTR_PURE from the code

We're using it incorrectly in many cases, and it doesn't help as far as
we know.

1 files changed, 7 insertions, 0 deletions

diff --git a/changes/pure_removal b/changes/pure_removal
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+  o Code simplifications and refactorings:
+    - Remove the pure attribute from all functions that used it previously.
+      In many cases this we assigned it incorrectly, because the functions
+      might assert or call impure functions, and we don't have evidence
+      that keeping the pure attribute is worthwhile. Implements changes
+      suggested in ticket 4421.
+