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

[Congcong Cai via cfe-commits]

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@@ -102,6 +102,211 @@ void BranchCloneCheck::registerMatchers(MatchFinder *Finder) {
       this);
   Finder->addMatcher(switchStmt().bind("switch"), this);
   Finder->addMatcher(conditionalOperator().bind("condOp"), this);
+  Finder->addMatcher(
+      ifStmt((hasThen(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))
----------------
HerrCai0907 wrote:

`!*I1 || !*I2` already be handled in `isIdenticalStmt`

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