[clang] [clang-tools-extra] [analyzer] Remove alpha.core.IdenticalExpr Checker (PR #114715)

[Julian Schmidt via cfe-commits]

================
@@ -102,6 +102,209 @@ void BranchCloneCheck::registerMatchers(MatchFinder *Finder) {
       this);
   Finder->addMatcher(switchStmt().bind("switch"), this);
   Finder->addMatcher(conditionalOperator().bind("condOp"), this);
+  Finder->addMatcher(ifStmt(hasDescendant(ifStmt())).bind("ifWithDescendantIf"),
+                     this);
+}
+
+/// Determines whether two statement trees are identical regarding
+/// operators and symbols.
+///
+/// Exceptions: expressions containing macros or functions with possible side
+/// effects are never considered identical.
+/// Limitations: (t + u) and (u + t) are not considered identical.
+/// t*(u + t) and t*u + t*t are not considered identical.
+///
+static bool isIdenticalStmt(const ASTContext &Ctx, const Stmt *Stmt1,
+                            const Stmt *Stmt2, bool IgnoreSideEffects) {
+
+  if (!Stmt1 || !Stmt2) {
+    return !Stmt1 && !Stmt2;
+  }
+
+  // If Stmt1 & Stmt2 are of different class then they are not
+  // identical statements.
+  if (Stmt1->getStmtClass() != Stmt2->getStmtClass())
+    return false;
+
+  const auto *Expr1 = dyn_cast<Expr>(Stmt1);
+  const auto *Expr2 = dyn_cast<Expr>(Stmt2);
+
+  if (Expr1 && Expr2) {
+    // If Stmt1 has side effects then don't warn even if expressions
+    // are identical.
+    if (!IgnoreSideEffects && Expr1->HasSideEffects(Ctx))
+      return false;
+    // If either expression comes from a macro then don't warn even if
+    // the expressions are identical.
+    if ((Expr1->getExprLoc().isMacroID()) || (Expr2->getExprLoc().isMacroID()))
+      return false;
+
+    // If all children of two expressions are identical, return true.
+    Expr::const_child_iterator I1 = Expr1->child_begin();
+    Expr::const_child_iterator I2 = Expr2->child_begin();
+    while (I1 != Expr1->child_end() && I2 != Expr2->child_end()) {
+      if (!*I1 || !*I2 || !isIdenticalStmt(Ctx, *I1, *I2, IgnoreSideEffects))
+        return false;
+      ++I1;
+      ++I2;
+    }
+    // If there are different number of children in the statements, return
+    // false.
+    if (I1 != Expr1->child_end())
+      return false;
+    if (I2 != Expr2->child_end())
+      return false;
+  }
+
+  switch (Stmt1->getStmtClass()) {
+  default:
+    return false;
+  case Stmt::CallExprClass:
+  case Stmt::ArraySubscriptExprClass:
+  case Stmt::ArraySectionExprClass:
+  case Stmt::OMPArrayShapingExprClass:
+  case Stmt::OMPIteratorExprClass:
+  case Stmt::ImplicitCastExprClass:
+  case Stmt::ParenExprClass:
+  case Stmt::BreakStmtClass:
+  case Stmt::ContinueStmtClass:
+  case Stmt::NullStmtClass:
+    return true;
+  case Stmt::CStyleCastExprClass: {
+    const auto *CastExpr1 = cast<CStyleCastExpr>(Stmt1);
+    const auto *CastExpr2 = cast<CStyleCastExpr>(Stmt2);
+
+    return CastExpr1->getTypeAsWritten() == CastExpr2->getTypeAsWritten();
+  }
+  case Stmt::ReturnStmtClass: {
+    const auto *ReturnStmt1 = cast<ReturnStmt>(Stmt1);
+    const auto *ReturnStmt2 = cast<ReturnStmt>(Stmt2);
+
+    return isIdenticalStmt(Ctx, ReturnStmt1->getRetValue(),
+                           ReturnStmt2->getRetValue(), IgnoreSideEffects);
+  }
+  case Stmt::ForStmtClass: {
+    const auto *ForStmt1 = cast<ForStmt>(Stmt1);
+    const auto *ForStmt2 = cast<ForStmt>(Stmt2);
+
+    if (!isIdenticalStmt(Ctx, ForStmt1->getInit(), ForStmt2->getInit(),
+                         IgnoreSideEffects))
+      return false;
+    if (!isIdenticalStmt(Ctx, ForStmt1->getCond(), ForStmt2->getCond(),
+                         IgnoreSideEffects))
+      return false;
+    if (!isIdenticalStmt(Ctx, ForStmt1->getInc(), ForStmt2->getInc(),
+                         IgnoreSideEffects))
+      return false;
+    if (!isIdenticalStmt(Ctx, ForStmt1->getBody(), ForStmt2->getBody(),
+                         IgnoreSideEffects))
+      return false;
+    return true;
+  }
+  case Stmt::DoStmtClass: {
+    const auto *DStmt1 = cast<DoStmt>(Stmt1);
+    const auto *DStmt2 = cast<DoStmt>(Stmt2);
+
+    if (!isIdenticalStmt(Ctx, DStmt1->getCond(), DStmt2->getCond(),
+                         IgnoreSideEffects))
+      return false;
+    if (!isIdenticalStmt(Ctx, DStmt1->getBody(), DStmt2->getBody(),
+                         IgnoreSideEffects))
+      return false;
+    return true;
+  }
+  case Stmt::WhileStmtClass: {
+    const auto *WStmt1 = cast<WhileStmt>(Stmt1);
+    const auto *WStmt2 = cast<WhileStmt>(Stmt2);
+
+    if (!isIdenticalStmt(Ctx, WStmt1->getCond(), WStmt2->getCond(),
+                         IgnoreSideEffects))
+      return false;
+    if (!isIdenticalStmt(Ctx, WStmt1->getBody(), WStmt2->getBody(),
+                         IgnoreSideEffects))
+      return false;
+    return true;
+  }
+  case Stmt::IfStmtClass: {
+    const auto *IStmt1 = cast<IfStmt>(Stmt1);
+    const auto *IStmt2 = cast<IfStmt>(Stmt2);
+
+    if (!isIdenticalStmt(Ctx, IStmt1->getCond(), IStmt2->getCond(),
+                         IgnoreSideEffects))
+      return false;
+    if (!isIdenticalStmt(Ctx, IStmt1->getThen(), IStmt2->getThen(),
+                         IgnoreSideEffects))
+      return false;
+    if (!isIdenticalStmt(Ctx, IStmt1->getElse(), IStmt2->getElse(),
+                         IgnoreSideEffects))
+      return false;
+    return true;
+  }
+  case Stmt::CompoundStmtClass: {
+    const auto *CompStmt1 = cast<CompoundStmt>(Stmt1);
+    const auto *CompStmt2 = cast<CompoundStmt>(Stmt2);
+
+    if (CompStmt1->size() != CompStmt2->size())
+      return false;
+
+    CompoundStmt::const_body_iterator I1 = CompStmt1->body_begin();
+    CompoundStmt::const_body_iterator I2 = CompStmt2->body_begin();
+    while (I1 != CompStmt1->body_end() && I2 != CompStmt2->body_end()) {
+      if (!isIdenticalStmt(Ctx, *I1, *I2, IgnoreSideEffects))
+        return false;
+      ++I1;
+      ++I2;
+    }
----------------
5chmidti wrote:

This can be rewritten using `llvm::all_of` and `llvm::zip`

https://github.com/llvm/llvm-project/pull/114715