Renaming Detection








Finding changed identifiers in programs is 
important for program analysis and merging. Comparing 
two versions of a program is complicated 
if renaming occurred. Textual merging is highly 
unreliable if in one version, identifiers were 
renamed, while in the other version, code 
using the old identifiers was added or 
modified. A program that automatically detects renamed 
identifiers between pairs of program modules is 
presented. The detector is part of a 
suite of intelligent differencing and merging programs 
that exploit the static semantics of programming 
languages. The core of the renaming detector 
is language independent; a language-dependent frontend implements 
a generic symbol table that stores scopes, 
definitions, and references. A rule-based expert system 
finds the best matches between symbols. The 
detector works with multiple file pairs, taking 
into account renamings that affect arbitarily many 
files. Renaming detectors for Java and Scheme 
have been implemented and shown to scale 
to realistic project sizes. With automatic renaming 
detection, a new quality in program analysis 
and merging is achieveable.