Static Analysis

LIBRA attempts to make static analysis as easy and automated as possible; in most cases, you should not have to do anything to get analysis working other than to enable it via LIBRA_ANALYSIS=YES.

LIBRA attempts to detect the languages enabled for your cmake project, and sets the source files to pass to the analysis targets appropriately. This allows for inclusion of analysis tools which could be C/C++ only, and have them not cause errors when used of a project of an incompatible type. You should never have to set LIBRA_ANALYSIS_LANGUAGE directly to avoid warnings/errors.

LIBRA supports the following analysis tools; more may be added in the future:

• cppcheck - --inline-suppr is unconditionally passed.

• clang-check - No unusual baked-in cmdline args.

• clang-format - No unusual baked-in cmdline args.

• clang-tidy - --header-filter is set to <repo>/include/*, so errors from headers outside of there will not be shown.

Some of these tools have additional configuration variables–see project-local.cmake: How To Hook Into LIBRA for options.

All of these tools can run with compilation database (and generally work better with them), but can also work without IF you give it the correct #defines, includes, etc. LIBRA works as follows when autogenerating static analysis targets:

Target type	LIBRA action
Shared library	Used compdb if it exists, otherwise obtain {defs, includes, etc.} from target directly.
Static library	Used compdb if it exists, otherwise obtain {defs, includes, etc.} from target directly.
Interface library	Obtain {defs, includes, etc.} from target directly.

clang-tidy

Targets are created for each category of checks:

• abseil

• cppcoreguidelines

• readability

• hicpp

• bugprone

• cert

• performance

• portability

• concurrency

• modernize

• misc

• google

Because some warnings are enabled by default in each category, in order to ONLY get warnings from a given category when building the target for that category (e.g., only get modernize checks for make analyze-clang-tidy-modernize), LIBRA disables all checks via -* and then enables all checks for the category. This whitelisting approach works well, EXCEPT that something like the following in the effective .clang-tidy has no effect:

---
Checks:
  '-*,
  -cppcoreguidelines-pro-bounds-constant-array-index,
  -clang-diagnostic-*,
  -fuchsia-default-argument-calls,
  -fuchsia-overloaded-operator,
  -modernize-pass-by-values,
  -modernize-use-trailing-return-type
  '

This is expected because the docs for --checks says:

Comma-separated list of globs with optional '-' prefix. Globs are processed in
order of appearance in the list. Globs without '-' prefix add checks with
matching names to the set, globs with the '-' prefix remove checks with
matching names from the set of enabled checks. This option's value is appended
to the value of the 'Checks' option in .clang-tidy file, if any.

So, when using LIBRA’s automation, if you want to selectively disable checks within a category other than the ones which LIBRA disables, you can use LIBRA_CLANG_TIDY_EXTRA_ARGS as described in project-local.cmake: How To Hook Into LIBRA.