[clang] [Clang] Implement labelled type filtering for overflow/truncation sanitizers w/ SSCLs (PR #107332)

[Vitaly Buka via cfe-commits]

================
@@ -48,6 +49,59 @@ Example
   $ clang -fsanitize=address -fsanitize-ignorelist=ignorelist.txt foo.c ; ./a.out
   # No error report here.
 
+Usage with UndefinedBehaviorSanitizer
+=====================================
+
+The arithmetic overflow sanitizers ``unsigned-integer-overflow`` and
+``signed-integer-overflow`` as well as the implicit integer truncation
+sanitizers ``implicit-signed-integer-truncation`` and
+``implicit-unsigned-integer-truncation`` support the ability to adjust
+instrumentation based on type.
+
+.. code-block:: bash
+
+  $ cat foo.c
+  void foo() {
+    int a = 2147483647; // INT_MAX
+    ++a;                // Normally, an overflow with -fsanitize=signed-integer-overflow
+  }
+  $ cat ignorelist.txt
+  [signed-integer-overflow]
+  type:int
+  $ clang -fsanitize=signed-integer-overflow -fsanitize-ignorelist=ignorelist.txt foo.c ; ./a.out
+  # no signed-integer-overflow error
+
+For example, supplying the above ``ignorelist.txt`` to
+``-fsanitize-ignorelist=ignorelist.txt`` disables overflow sanitizer
+instrumentation for arithmetic operations containing values of type ``int``.
+
+The following SCL categories are supported: ``=no_sanitize`` and ``=sanitize``.
+The ``no_sanitize`` category is the default for any entry within an ignorelist
----------------
vitalybuka wrote:

> Actually 'SpecialCaseList::inSectionBlame' supports linenumber
> So we can make it work, with some refactoring, in future patches.

Looking trough code, I think the rule is simple any match of "sanitize" > "no_sanitize". Order is irrelevant.
I guess we can keep this way.
Please document.

Please add a test with different permutations, as I commented below.



https://github.com/llvm/llvm-project/pull/107332