Rust: Avoid location-based variable analysis #18462
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- rust/ql/lib/codeql/rust/elements/internal/VariableImpl.qll: Language not supported
- rust/ql/test/library-tests/dataflow/strings/inline-taint-flow.expected: Language not supported
- rust/ql/test/library-tests/variables/variables.ql: Language not supported
- rust/ql/test/query-tests/unusedentities/UnusedValue.expected: Language not supported
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Before this PR, we were relying on the source location of variable declarations and accesses for name-binding. However, this does not work for variables declared/accessed inside macros, where the original source locations are not available.
This PR consequently rewrites the logic to be purely AST based, by computing pre-order tree-traversal numbers for (relevant) AST nodes, and then using those numbers instead of source location start-line/columns.
This approach mostly works, except we are not able to respect the macro hygiene rules of Rust, since the extractor does not supply us with a syntax context. I originally noticed this in an earlier DCA run, where a new
rust/unused-variablefalse-positive result was added, and I have consequently added this FP to our test suite.Commit-by-commit review is suggested.