[clang-tidy] New util `Aliasing` factored out from `bugprone-infinite-loop`

[baloghadamsoftware]

Summary

Function hasPtrOrReferenceInfFunc() of bugprone-infinite-loop is a generic function which could be reused in another checks. This patch moves this function into a newly created utility module.

[gribozavr2]

clang-tools-extra/clang-tidy/utils/Aliasing.cpp

60

Please don't duplicate the comment from the header in the cpp file.

clang-tools-extra/clang-tidy/utils/Aliasing.h

19

Could you expand the comment? Best if you could add an example.

[baloghadamsoftware]

Thank you for the comment, @gribozavr2! Patch updated according to them.

[gribozavr2]

clang-tools-extra/clang-tidy/utils/Aliasing.h

29

Extra blank line.

[njames93]

clang-tools-extra/clang-tidy/utils/Aliasing.cpp

17

Ditto \p <Name>.

25

Ditto.

43

Ditto.

clang-tools-extra/clang-tidy/utils/Aliasing.h

18

Don't use double ticks for param names, instead use \p <Name>.

[baloghadamsoftware]

Parameters in comments changed to \p <Name>.

[njames93]

LGTM, but with one more nit

clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp

16

This function is only used once in the file, so may as well remove this line and just qualify its call further down.

60

here.

clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp

 //===--- InfiniteLoopCheck.cpp - clang-tidy -------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "InfiniteLoopCheck.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Analysis/Analyses/ExprMutationAnalyzer.h"
+#include "../utils/Aliasing.h"
 
 using namespace clang::ast_matchers;
+using clang::tidy::utils::hasPtrOrReferenceInFunc;
 
 namespace clang {
 namespace tidy {
 namespace bugprone {
 
 static internal::Matcher<Stmt>
 loopEndingStmt(internal::Matcher<Stmt> Internal) {
   return stmt(anyOf(breakStmt(Internal), returnStmt(Internal),
                     gotoStmt(Internal), cxxThrowExpr(Internal),
                     callExpr(Internal, callee(functionDecl(isNoReturn())))));
 }
 
-/// Return whether `S` is a reference to the declaration of `Var`.
-static bool isAccessForVar(const Stmt *S, const VarDecl *Var) {
-  if (const auto *DRE = dyn_cast<DeclRefExpr>(S))
-    return DRE->getDecl() == Var;
-
-  return false;
-}
-
-/// Return whether `Var` has a pointer or reference in `S`.
-static bool isPtrOrReferenceForVar(const Stmt *S, const VarDecl *Var) {
-  if (const auto *DS = dyn_cast<DeclStmt>(S)) {
-    for (const Decl *D : DS->getDeclGroup()) {
-      if (const auto *LeftVar = dyn_cast<VarDecl>(D)) {
-        if (LeftVar->hasInit() && LeftVar->getType()->isReferenceType()) {
-          return isAccessForVar(LeftVar->getInit(), Var);
-        }
-      }
-    }
-  } else if (const auto *UnOp = dyn_cast<UnaryOperator>(S)) {
-    if (UnOp->getOpcode() == UO_AddrOf)
-      return isAccessForVar(UnOp->getSubExpr(), Var);
-  }
-
-  return false;
-}
-
-/// Return whether `Var` has a pointer or reference in `S`.
-static bool hasPtrOrReferenceInStmt(const Stmt *S, const VarDecl *Var) {
-  if (isPtrOrReferenceForVar(S, Var))
-    return true;
-
-  for (const Stmt *Child : S->children()) {
-    if (!Child)
-      continue;
-
-    if (hasPtrOrReferenceInStmt(Child, Var))
-      return true;
-  }
-
-  return false;
-}
-
-/// Return whether `Var` has a pointer or reference in `Func`.
-static bool hasPtrOrReferenceInFunc(const FunctionDecl *Func,
-                                    const VarDecl *Var) {
-  return hasPtrOrReferenceInStmt(Func->getBody(), Var);
-}
-
 /// Return whether `Var` was changed in `LoopStmt`.
 static bool isChanged(const Stmt *LoopStmt, const VarDecl *Var,
                       ASTContext *Context) {
   if (const auto *ForLoop = dyn_cast<ForStmt>(LoopStmt))
     return (ForLoop->getInc() &&
             ExprMutationAnalyzer(*ForLoop->getInc(), *Context)
                 .isMutated(Var)) ||
            (ForLoop->getBody() &&
if (const auto *Var = dyn_cast<VarDecl>(DRE->getDecl())) {
         return true;
 
       if (Var->getType().isVolatileQualified())
         return true;
 
       if (!Var->getType().getTypePtr()->isIntegerType())
         return true;
 
       return hasPtrOrReferenceInFunc(Func, Var) ||
              isChanged(LoopStmt, Var, Context);
       // FIXME: Track references.
     }
   } else if (isa<MemberExpr>(Cond) || isa<CallExpr>(Cond)) {
     // FIXME: Handle MemberExpr.
     return true;
   }
 

clang-tools-extra/clang-tidy/utils/Aliasing.h

+//===------------- Aliasing.h - clang-tidy --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_UTILS_ALIASING_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_UTILS_ALIASING_H
+
+#include "clang/AST/Decl.h"
+
+namespace clang {
+namespace tidy {
+namespace utils {
+
+/// Returns whether ``Var`` has a pointer or reference in ``Func``.
+///
+/// Example:
+/// void f() {
+///   int n;
+///   ...
+///   int *p = &n;
+/// }
+///
+/// For ``f()`` and ``n`` the function returns ``true`` because ``p`` is a
+/// pointer to ``n`` created in ``f()``.
+
+bool hasPtrOrReferenceInFunc(const FunctionDecl *Func, const VarDecl *Var);
+
+} // namespace utils
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_UTILS_ALIASING_H

clang-tools-extra/clang-tidy/utils/Aliasing.cpp

+//===------------- Aliasing.cpp - clang-tidy ------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Aliasing.h"
+
+#include "clang/AST/Expr.h"
+
+namespace clang {
+namespace tidy {
+namespace utils {
+
+/// Return whether `S` is a reference to the declaration of `Var`.
+static bool isAccessForVar(const Stmt *S, const VarDecl *Var) {
+  if (const auto *DRE = dyn_cast<DeclRefExpr>(S))
+    return DRE->getDecl() == Var;
+
+  return false;
+}
+
+/// Return whether `Var` has a pointer or reference in `S`.
+static bool isPtrOrReferenceForVar(const Stmt *S, const VarDecl *Var) {
+  if (const auto *DS = dyn_cast<DeclStmt>(S)) {
+    for (const Decl *D : DS->getDeclGroup()) {
+      if (const auto *LeftVar = dyn_cast<VarDecl>(D)) {
+        if (LeftVar->hasInit() && LeftVar->getType()->isReferenceType()) {
+          return isAccessForVar(LeftVar->getInit(), Var);
+        }
+      }
+    }
+  } else if (const auto *UnOp = dyn_cast<UnaryOperator>(S)) {
+    if (UnOp->getOpcode() == UO_AddrOf)
+      return isAccessForVar(UnOp->getSubExpr(), Var);
+  }
+
+  return false;
+}
+
+/// Return whether `Var` has a pointer or reference in `S`.
+static bool hasPtrOrReferenceInStmt(const Stmt *S, const VarDecl *Var) {
+  if (isPtrOrReferenceForVar(S, Var))
+    return true;
+
+  for (const Stmt *Child : S->children()) {
+    if (!Child)
+      continue;
+
+    if (hasPtrOrReferenceInStmt(Child, Var))
+      return true;
+  }
+
+  return false;
+}
+
+bool hasPtrOrReferenceInFunc(const FunctionDecl *Func, const VarDecl *Var) {
+  return hasPtrOrReferenceInStmt(Func->getBody(), Var);
+}
+
+} // namespace utils
+} // namespace tidy
+} // namespace clang

clang-tools-extra/clang-tidy/utils/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   FrontendOpenMP
   Support
   )
 
 add_clang_library(clangTidyUtils
+  Aliasing.cpp
   ASTUtils.cpp
   DeclRefExprUtils.cpp
   ExceptionAnalyzer.cpp
   ExprSequence.cpp
   FileExtensionsUtils.cpp
   FixItHintUtils.cpp
   HeaderGuard.cpp
   IncludeInserter.cpp