[clang] Optimize -Wunsafe-buffer-usage. (PR #124554)

[via cfe-commits]

================
@@ -186,106 +205,202 @@ class MatchDescendantVisitor : public DynamicRecursiveASTVisitor {
     return DynamicRecursiveASTVisitor::TraverseStmt(Node);
   }
 
+  void set_ast_context(ASTContext &Context) { ActiveASTContext = &Context; }
+
+  void set_handler(const UnsafeBufferUsageHandler &NewHandler) {
+    Handler = &NewHandler;
+  }
+
 private:
   // Sets 'Matched' to true if 'Matcher' matches 'Node'
   //
   // Returns 'true' if traversal should continue after this function
   // returns, i.e. if no match is found or 'Bind' is 'BK_All'.
   template <typename T> bool match(const T &Node) {
-    internal::BoundNodesTreeBuilder RecursiveBuilder(*Builder);
-
-    if (Matcher->matches(DynTypedNode::create(Node), Finder,
-                         &RecursiveBuilder)) {
-      ResultBindings.addMatch(RecursiveBuilder);
+    if (Matcher->matches(DynTypedNode::create(Node), *ActiveASTContext,
+                         *Handler)) {
       Matches = true;
-      if (Bind != internal::ASTMatchFinder::BK_All)
+      if (!BindAll)
         return false; // Abort as soon as a match is found.
     }
     return true;
   }
 
-  const internal::DynTypedMatcher *const Matcher;
-  internal::ASTMatchFinder *const Finder;
-  internal::BoundNodesTreeBuilder *const Builder;
-  internal::BoundNodesTreeBuilder ResultBindings;
-  const internal::ASTMatchFinder::BindKind Bind;
+  CustomMatcher *const Matcher;
+  /// Defines how bindings are processed on recursive matches.
+  /// true: Create results for all combinations of bindings that match.
+  /// false: Stop at the first match and only bind the first match.
+  const bool BindAll;
   bool Matches;
   bool ignoreUnevaluatedContext;
+  ASTContext *ActiveASTContext;
+  const UnsafeBufferUsageHandler *Handler;
 };
 
 // Because we're dealing with raw pointers, let's define what we mean by that.
-static auto hasPointerType() {
-  return hasType(hasCanonicalType(pointerType()));
+static auto hasPointerType(const Expr &E) {
+  return isa<PointerType>(E.getType().getCanonicalType());
 }
 
-static auto hasArrayType() { return hasType(hasCanonicalType(arrayType())); }
-
-AST_MATCHER_P(Stmt, forEachDescendantEvaluatedStmt, internal::Matcher<Stmt>,
-              innerMatcher) {
-  const DynTypedMatcher &DTM = static_cast<DynTypedMatcher>(innerMatcher);
-
-  MatchDescendantVisitor Visitor(&DTM, Finder, Builder, ASTMatchFinder::BK_All,
-                                 true);
-  return Visitor.findMatch(DynTypedNode::create(Node));
-}
-
-AST_MATCHER_P(Stmt, forEachDescendantStmt, internal::Matcher<Stmt>,
-              innerMatcher) {
-  const DynTypedMatcher &DTM = static_cast<DynTypedMatcher>(innerMatcher);
-
-  MatchDescendantVisitor Visitor(&DTM, Finder, Builder, ASTMatchFinder::BK_All,
-                                 false);
-  return Visitor.findMatch(DynTypedNode::create(Node));
+static auto hasArrayType(const Expr &E) {
+  return isa<ArrayType>(E.getType().getCanonicalType());
 }
 
 // Matches a `Stmt` node iff the node is in a safe-buffer opt-out region
-AST_MATCHER_P(Stmt, notInSafeBufferOptOut, const UnsafeBufferUsageHandler *,
-              Handler) {
+static bool notInSafeBufferOptOut(const Stmt &Node,
+                                  const UnsafeBufferUsageHandler *Handler) {
   return !Handler->isSafeBufferOptOut(Node.getBeginLoc());
 }
 
-AST_MATCHER_P(Stmt, ignoreUnsafeBufferInContainer,
-              const UnsafeBufferUsageHandler *, Handler) {
+static bool
+ignoreUnsafeBufferInContainer(const Stmt &Node,
+                              const UnsafeBufferUsageHandler *Handler) {
   return Handler->ignoreUnsafeBufferInContainer(Node.getBeginLoc());
 }
 
-AST_MATCHER_P(Stmt, ignoreUnsafeLibcCall, const UnsafeBufferUsageHandler *,
-              Handler) {
-  if (Finder->getASTContext().getLangOpts().CPlusPlus)
+static bool ignoreUnsafeLibcCall(const Stmt &Node, const ASTContext &Ctx,
+                                 const UnsafeBufferUsageHandler *Handler) {
+  if (Ctx.getLangOpts().CPlusPlus)
     return Handler->ignoreUnsafeBufferInLibcCall(Node.getBeginLoc());
   return true; /* Only warn about libc calls for C++ */
 }
 
-AST_MATCHER_P(CastExpr, castSubExpr, internal::Matcher<Expr>, innerMatcher) {
-  return innerMatcher.matches(*Node.getSubExpr(), Finder, Builder);
+// Finds any expression 'e' such that `innerMatcher`
+// matches 'e' and 'e' is in an Unspecified Lvalue Context.
+static void findStmtsInUnspecifiedLvalueContext(
+    const Stmt *S, const llvm::function_ref<void(const Expr *)> InnerMatcher) {
+  if (const auto *CE = dyn_cast<ImplicitCastExpr>(S)) {
+    if (CE->getCastKind() != CastKind::CK_LValueToRValue)
+      return;
+    InnerMatcher(CE->getSubExpr());
+  }
+  if (const auto *BO = dyn_cast<BinaryOperator>(S)) {
+    if (BO->getOpcode() != BO_Assign)
+      return;
+    InnerMatcher(BO->getLHS());
+  }
 }
 
-// Matches a `UnaryOperator` whose operator is pre-increment:
-AST_MATCHER(UnaryOperator, isPreInc) {
-  return Node.getOpcode() == UnaryOperator::Opcode::UO_PreInc;
+/// Note: Copied and modified from ASTMatchers.
+/// Matches all arguments and their respective types for a \c CallExpr or
+/// \c CXXConstructExpr. It is very similar to \c forEachArgumentWithParam but
+/// it works on calls through function pointers as well.
+///
+/// The difference is, that function pointers do not provide access to a
+/// \c ParmVarDecl, but only the \c QualType for each argument.
+///
+/// Given
+/// \code
+///   void f(int i);
+///   int y;
+///   f(y);
+///   void (*f_ptr)(int) = f;
+///   f_ptr(y);
+/// \endcode
+/// callExpr(
+///   forEachArgumentWithParamType(
+///     declRefExpr(to(varDecl(hasName("y")))),
+///     qualType(isInteger()).bind("type)
+/// ))
+///   matches f(y) and f_ptr(y)
+/// with declRefExpr(...)
+///   matching int y
+/// and qualType(...)
+///   matching int
+static void forEachArgumentWithParamType(
+    const CallExpr &Node,
+    const llvm::function_ref<void(const Stmt *)> ArgMatcher,
----------------
ivanaivanovska wrote:

Done.

https://github.com/llvm/llvm-project/pull/124554