[Clang] Overflow Pattern Exclusion - rename some patterns, enhance docs (#105709)

From @vitalybuka's review on
https://github.com/llvm/llvm-project/pull/104889:
- [x] remove unused variable in tests
- [x] rename `post-decr-while` --> `unsigned-post-decr-while`
- [x] split `add-overflow-test` into `add-unsigned-overflow-test` and
`add-signed-overflow-test`
- [x] be more clear about defaults within docs
- [x] add table to docs

Here's a screenshot of the rendered table so you don't have to build the
html docs yourself to inspect the layout:

![image](https://github.com/user-attachments/assets/5d3497c4-5f5a-4579-b29b-96a0fd192faa)


CCs: @vitalybuka

---------

Signed-off-by: Justin Stitt <justinstitt@google.com>
Co-authored-by: Vitaly Buka <vitalybuka@google.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index f510d30..0bb4175 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -4274,9 +4274,13 @@ bool CompilerInvocation::ParseLangArgs(LangOptions &Opts, ArgList &Args,
           llvm::StringSwitch<unsigned>(A->getValue(i))
               .Case("none", LangOptionsBase::None)
               .Case("all", LangOptionsBase::All)
-              .Case("add-overflow-test", LangOptionsBase::AddOverflowTest)
+              .Case("add-unsigned-overflow-test",
+                    LangOptionsBase::AddUnsignedOverflowTest)
+              .Case("add-signed-overflow-test",
+                    LangOptionsBase::AddSignedOverflowTest)
               .Case("negated-unsigned-const", LangOptionsBase::NegUnsignedConst)
-              .Case("post-decr-while", LangOptionsBase::PostDecrInWhile)
+              .Case("unsigned-post-decr-while",
+                    LangOptionsBase::PostDecrInWhile)
               .Default(0);
     }
   }