`A2-10-1`: False positive around null identifiers on tuple-like types in structural binding (relevant C++17 only)
Nobody has claimed this yet.
Assessment
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Newbie friendliness
- 35/100
Research direction
Start with the finding in openpilot's dmonitoring.cc:82:10 and inspect IdentifierHiding.ql to see how unnamed tuple-like bindings are identified. Then review the tuple.h stub and compile the provided structured-binding example. Done means the example compiles with tuple elements and successive bindings no longer trigger a false positive.
Written by the indexing model from the issue text.
Description
Affected rules
- A2-10-1
- RULE-5-3
- M0-1-3
Description
the extractor creates local variables for each identifier, and one for the entire binding. The later is of type tuple without a name, so it gets (null) .
This means if you have another structured binding later on, the rule is falsely triggered because the name is the same.
Example
#include <tuple>
void f9(int x, int y){
auto tup = std::make_tuple(1, 2);
const auto & [ a, b ] = tup;
const auto & [ c, d ] = tup;
}
this example will require additional stubbing to be added to the tuple.h stub, as it currently will not compile due to tuples in that stub not currently having elements. Compilation error message: error: type 'const std::tuple<int, int>' decomposes into 0 elements, but 2 names were provided (ie needs to have mechanism to have elements and get those elements)
another example is the current finding in openpilot- dmonitoring.cc:82:10 from query IdentifierHiding.ql
- Dominant language
- CodeQL
- Stars
- 227
- Forks
- 82
- Avg merge
- 6d 7h
- Merged PRs (30d)
- 9
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
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