C++: Add heuristic for GNU autoconf config files#21661
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jketema merged 2 commits intogithub:mainfrom Apr 7, 2026
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Pull request overview
Adds detection for GNU autoconf-generated conftest* configuration test files so CodeQL C/C++ queries can exclude them (reducing noise), and introduces targeted regression tests.
Changes:
- Added
AutoconfConfigureTestFileas a newConfigurationTestFilesubclass. - Added ExprHasNoEffect query-test fixtures/expectations for autoconf-style
conftest*files. - Added a change note documenting the new heuristic.
Show a summary per file
| File | Description |
|---|---|
| cpp/ql/lib/semmle/code/cpp/ConfigurationTestFile.qll | Adds AutoconfConfigureTestFile to recognize autoconf conftest* files. |
| cpp/ql/lib/change-notes/2026-04-07-autoconf.md | Documents the new configuration-test-file heuristic. |
| cpp/ql/test/query-tests/Likely Bugs/Likely Typos/ExprHasNoEffect/autoconf/ExprHasNoEffect.qlref | Points the new autoconf test folder at the existing query. |
| cpp/ql/test/query-tests/Likely Bugs/Likely Typos/ExprHasNoEffect/autoconf/ExprHasNoEffect.expected | Asserts which autoconf fixtures should/shouldn’t be excluded. |
| cpp/ql/test/query-tests/Likely Bugs/Likely Typos/ExprHasNoEffect/autoconf/conftest.h | Shared header for the autoconf test fixtures. |
| cpp/ql/test/query-tests/Likely Bugs/Likely Typos/ExprHasNoEffect/autoconf/conftest.c | Autoconf fixture intended to be excluded by the heuristic. |
| cpp/ql/test/query-tests/Likely Bugs/Likely Typos/ExprHasNoEffect/autoconf/conftest.cpp | Autoconf fixture intended to be excluded by the heuristic. |
| cpp/ql/test/query-tests/Likely Bugs/Likely Typos/ExprHasNoEffect/autoconf/conftest123.c | Autoconf fixture intended to be excluded by the heuristic. |
| cpp/ql/test/query-tests/Likely Bugs/Likely Typos/ExprHasNoEffect/autoconf/conftest.c.c | Autoconf fixture intended not to match the heuristic (still flagged). |
| cpp/ql/test/query-tests/Likely Bugs/Likely Typos/ExprHasNoEffect/autoconf/conftest_abc.c | Autoconf fixture intended not to match the heuristic (still flagged). |
Copilot's findings
- Files reviewed: 10/10 changed files
- Comments generated: 5
cpp/ql/test/query-tests/Likely Bugs/Likely Typos/ExprHasNoEffect/autoconf/conftest.c.c
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cpp/ql/test/query-tests/Likely Bugs/Likely Typos/ExprHasNoEffect/autoconf/conftest_abc.c
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cpp/ql/test/query-tests/Likely Bugs/Likely Typos/ExprHasNoEffect/autoconf/conftest.c
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cpp/ql/test/query-tests/Likely Bugs/Likely Typos/ExprHasNoEffect/autoconf/conftest.cpp
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cpp/ql/test/query-tests/Likely Bugs/Likely Typos/ExprHasNoEffect/autoconf/conftest123.c
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IdrissRio
approved these changes
Apr 7, 2026
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IdrissRio
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LGTM 👍
Let's wait for DCA
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DCA looks ok. This silences some of the conftest errors on nmap. |
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