[PATCH] D125709: [analyzer][Casting] Support isa, cast, dyn_cast of SVals

[Balázs Benics via Phabricator via cfe-commits]

steakhal created this revision.
steakhal added reviewers: NoQ, martong, Szelethus, balazske, ASDenysPetrov, bzcheeseman.
Herald added subscribers: manas, dkrupp, donat.nagy, mikhail.ramalho, a.sidorin, rnkovacs, szepet, baloghadamsoftware, xazax.hun.
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steakhal requested review of this revision.
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This change specializes the LLVM RTTI mechanism for SVals.
After this change, we can use the well-known `isa`, `cast`, `dyn_cast`.

Examples:

  // SVal V = ...;
  // Loc MyLoc = ...;
  
  bool IsInteresting = isa<loc::MemRegionVal, loc::GotoLabel>(MyLoc);
  auto MRV = cast<loc::MemRegionVal>(MyLoc);
  Optional<loc::MemRegionVal> MaybeMRV = dyn_cast<loc::MemRegionVal>(V)

The current `SVal::getAs` and `castAs` member functions are redundant at
this point, but I believe that they are still handy.

The member function version is terse and reads left-to-right, which IMO
is a great plus. However, we should probably add a variadic `isa` member
function version to have the same casting API in both cases.

I'm not sure, shall I add tests?

Thanks for the extensive TMP help @bzcheeseman!


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D125709

Files:
  clang/include/clang/StaticAnalyzer/Core/PathSensitive/SVals.h


Index: clang/include/clang/StaticAnalyzer/Core/PathSensitive/SVals.h
===================================================================
--- clang/include/clang/StaticAnalyzer/Core/PathSensitive/SVals.h
+++ clang/include/clang/StaticAnalyzer/Core/PathSensitive/SVals.h
@@ -571,4 +571,28 @@
 } // namespace ento
 } // namespace clang
 
+namespace llvm {
+template <typename To, typename From>
+struct CastInfo<
+    To, From,
+    std::enable_if_t<std::is_base_of<::clang::ento::SVal, From>::value>>
+    : public CastIsPossible<To, ::clang::ento::SVal> {
+  using Self = CastInfo<
+      To, From,
+      std::enable_if_t<std::is_base_of<::clang::ento::SVal, From>::value>>;
+  static bool isPossible(const From &V) {
+    return To::classof(*static_cast<const ::clang::ento::SVal *>(&V));
+  }
+  static Optional<To> castFailed() { return Optional<To>{}; }
+  static Optional<To> doCast(const From &f) {
+    return *static_cast<const To *>(cast<::clang::ento::SVal>(&f));
+  }
+  static Optional<To> doCastIfPossible(const From &f) {
+    if (!Self::isPossible(f))
+      return Self::castFailed();
+    return doCast(f);
+  }
+};
+} // namespace llvm
+
 #endif // LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SVALS_H


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