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Diffstat (limited to 'docs/ReleaseNotes.rst')
| -rw-r--r-- | docs/ReleaseNotes.rst | 32 |
1 files changed, 30 insertions, 2 deletions
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst index 342fed3393b18..1e45a13ef9161 100644 --- a/docs/ReleaseNotes.rst +++ b/docs/ReleaseNotes.rst @@ -46,7 +46,9 @@ sections with improvements to Clang's support for those languages. Major New Features ------------------ -- ... +- A new Implicit Conversion Sanitizer (``-fsanitize=implicit-conversion``) group + was added. Please refer to the :ref:`release-notes-ubsan` section of the + release notes for the details. Improvements to Clang's diagnostics ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -280,10 +282,36 @@ Static Analyzer ... +.. _release-notes-ubsan: + Undefined Behavior Sanitizer (UBSan) ------------------------------------ -* ... +* A new Implicit Conversion Sanitizer (``-fsanitize=implicit-conversion``) group + was added. + + Currently, only one type of issues is caught - implicit integer truncation + (``-fsanitize=implicit-integer-truncation``), also known as integer demotion. + While there is a ``-Wconversion`` diagnostic group that catches this kind of + issues, it is both noisy, and does not catch **all** the cases. + + .. code-block:: c++ + + unsigned char store = 0; + + bool consume(unsigned int val); + + void test(unsigned long val) { + if (consume(val)) // the value may have been silently truncated. + store = store + 768; // before addition, 'store' was promoted to int. + (void)consume((unsigned int)val); // OK, the truncation is explicit. + } + + Just like other ``-fsanitize=integer`` checks, these issues are **not** + undefined behaviour. But they are not *always* intentional, and are somewhat + hard to track down. This group is **not** enabled by ``-fsanitize=undefined``, + but the ``-fsanitize=implicit-integer-truncation`` check + is enabled by ``-fsanitize=integer``. Core Analysis Improvements ========================== |