[clang-tidy] Add cppcoreguidelines-avoid-do-while check

Implements rule ES.75 of C++ Core Guidelines.

Differential Revision: https://reviews.llvm.org/D132461

clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidDoWhileCheck.cpp

@@ -0,0 +1,41 @@
+//===--- AvoidDoWhileCheck.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 "AvoidDoWhileCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace cppcoreguidelines {
+
+AvoidDoWhileCheck::AvoidDoWhileCheck(StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      IgnoreMacros(Options.getLocalOrGlobal("IgnoreMacros", false)) {}
+
+void AvoidDoWhileCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "IgnoreMacros", IgnoreMacros);
+}
+
+void AvoidDoWhileCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(doStmt().bind("x"), this);
+}
+
+void AvoidDoWhileCheck::check(const MatchFinder::MatchResult &Result) {
+  if (const auto *MatchedDecl = Result.Nodes.getNodeAs<DoStmt>("x")) {
+    if (IgnoreMacros && MatchedDecl->getBeginLoc().isMacroID())
+      return;
+    diag(MatchedDecl->getBeginLoc(), "avoid do-while loops");
+  }
+}
+
+} // namespace cppcoreguidelines
+} // namespace tidy
+} // namespace clang

clang-tools-extra/clang-tidy/cppcoreguidelines/AvoidDoWhileCheck.h

@@ -0,0 +1,41 @@
+//===--- AvoidDoWhileCheck.h - clang-tidy -----------------------*- C++ -*-===//
+//
+// 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_CPPCOREGUIDELINES_AVOIDDOWHILECHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_AVOIDDOWHILECHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang {
+namespace tidy {
+namespace cppcoreguidelines {
+
+/// do-while loops are less readable than plan while loops, and can lead to
+/// subtle bugs.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines/avoid-do-while.html
+class AvoidDoWhileCheck : public ClangTidyCheck {
+public:
+  AvoidDoWhileCheck(StringRef Name, ClangTidyContext *Context);
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+    return LangOpts.CPlusPlus;
+  }
+  void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+  bool IgnoreMacros;
+};
+
+} // namespace cppcoreguidelines
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_AVOIDDOWHILECHECK_H

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

@@ -5,6 +5,7 @@ set(LLVM_LINK_COMPONENTS
 
 add_clang_library(clangTidyCppCoreGuidelinesModule
   AvoidConstOrRefDataMembersCheck.cpp
+  AvoidDoWhileCheck.cpp
   AvoidGotoCheck.cpp
   AvoidNonConstGlobalVariablesCheck.cpp
   CppCoreGuidelinesTidyModule.cpp

clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp

@@ -15,6 +15,7 @@
 #include "../modernize/UseOverrideCheck.h"
 #include "../readability/MagicNumbersCheck.h"
 #include "AvoidConstOrRefDataMembersCheck.h"
+#include "AvoidDoWhileCheck.h"
 #include "AvoidGotoCheck.h"
 #include "AvoidNonConstGlobalVariablesCheck.h"
 #include "InitVariablesCheck.h"
@@ -50,6 +51,8 @@ class CppCoreGuidelinesModule : public ClangTidyModule {
         "cppcoreguidelines-avoid-c-arrays");
     CheckFactories.registerCheck<AvoidConstOrRefDataMembersCheck>(
         "cppcoreguidelines-avoid-const-or-ref-data-members");
+    CheckFactories.registerCheck<AvoidDoWhileCheck>(
+        "cppcoreguidelines-avoid-do-while");
     CheckFactories.registerCheck<AvoidGotoCheck>(
         "cppcoreguidelines-avoid-goto");
     CheckFactories.registerCheck<readability::MagicNumbersCheck>(

clang-tools-extra/docs/ReleaseNotes.rst

@@ -110,6 +110,11 @@ New checks
 
   Warns when a struct or class uses const or reference (lvalue or rvalue) data members.
 
+- New :doc:`cppcoreguidelines-avoid-do-while
+  <clang-tidy/checks/cppcoreguidelines/avoid-do-while>` check.
+
+  Warns when using ``do-while`` loops.
+
 New check aliases
 ^^^^^^^^^^^^^^^^^
 

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/avoid-do-while.rst

@@ -0,0 +1,38 @@
+.. title:: clang-tidy - cppcoreguidelines-avoid-do-while
+
+cppcoreguidelines-avoid-do-while
+================================
+
+Warns when using ``do-while`` loops. They are less readable than plain ``while``
+loops, since the termination condition is at the end and the condition is not
+checked prior to the first iteration. This can lead to subtle bugs.
+
+The check implements
+`rule ES.75 of C++ Core Guidelines <https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#Res-do>`_.
+
+Examples:
+
+.. code-block:: c++
+
+  int x;
+  do {
+      std::cin >> x;
+      // ...
+  } while (x < 0);
+
+Options
+-------
+
+.. option:: IgnoreMacros
+
+  Ignore the check when analyzing macros. This is useful for safely defining function-like macros:
+
+  .. code-block:: c++
+
+    #define FOO_BAR(x) \
+    do { \
+      foo(x); \
+      bar(x); \
+    } while(0)
+
+  Defaults to `false`.

clang-tools-extra/docs/clang-tidy/checks/list.rst

@@ -178,6 +178,7 @@ Clang-Tidy Checks
    `concurrency-mt-unsafe <concurrency/mt-unsafe.html>`_,
    `concurrency-thread-canceltype-asynchronous <concurrency/thread-canceltype-asynchronous.html>`_,
    `cppcoreguidelines-avoid-const-or-ref-data-members <cppcoreguidelines/avoid-const-or-ref-data-members.html>`_,
+   `cppcoreguidelines-avoid-do-while <cppcoreguidelines/avoid-do-while.html>`_,
    `cppcoreguidelines-avoid-goto <cppcoreguidelines/avoid-goto.html>`_,
    `cppcoreguidelines-avoid-non-const-global-variables <cppcoreguidelines/avoid-non-const-global-variables.html>`_,
    `cppcoreguidelines-init-variables <cppcoreguidelines/init-variables.html>`_, "Yes"

clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/avoid-do-while.cpp

@@ -0,0 +1,88 @@
+// RUN: %check_clang_tidy -check-suffixes=DEFAULT       %s cppcoreguidelines-avoid-do-while %t
+// RUN: %check_clang_tidy -check-suffixes=IGNORE-MACROS %s cppcoreguidelines-avoid-do-while %t -- -config='{CheckOptions: [{key: cppcoreguidelines-avoid-do-while.IgnoreMacros, value: true}]}'
+
+#define FOO(x) \
+  do { \
+  } while (x != 0)
+
+#define BAR_0(x) \
+  do { \
+    bar(x); \
+  } while (0)
+
+#define BAR_FALSE(x) \
+  do { \
+    bar(x); \
+  } while (false)
+
+void bar(int);
+int baz();
+
+void foo()
+{
+    // CHECK-MESSAGES-IGNORE-MACROS: :[[@LINE+2]]:5: warning: avoid do-while loops [cppcoreguidelines-avoid-do-while]
+    // CHECK-MESSAGES-DEFAULT: :[[@LINE+1]]:5: warning: avoid do-while loops [cppcoreguidelines-avoid-do-while]
+    do {
+
+    } while(0);
+
+    // CHECK-MESSAGES-IGNORE-MACROS: :[[@LINE+2]]:5: warning: avoid do-while loops
+    // CHECK-MESSAGES-DEFAULT: :[[@LINE+1]]:5: warning: avoid do-while loops
+    do {
+
+    } while(1);
+
+    // CHECK-MESSAGES-IGNORE-MACROS: :[[@LINE+2]]:5: warning: avoid do-while loops
+    // CHECK-MESSAGES-DEFAULT: :[[@LINE+1]]:5: warning: avoid do-while loops
+    do {
+
+    } while(-1);
+
+    // CHECK-MESSAGES-IGNORE-MACROS: :[[@LINE+2]]:5: warning: avoid do-while loops
+    // CHECK-MESSAGES-DEFAULT: :[[@LINE+1]]:5: warning: avoid do-while loops
+    do {
+
+    } while(false);
+
+    // CHECK-MESSAGES-IGNORE-MACROS: :[[@LINE+2]]:5: warning: avoid do-while loops
+    // CHECK-MESSAGES-DEFAULT: :[[@LINE+1]]:5: warning: avoid do-while loops
+    do {
+
+    } while(true);
+
+    // CHECK-MESSAGES-IGNORE-MACROS: :[[@LINE+3]]:5: warning: avoid do-while loops
+    // CHECK-MESSAGES-DEFAULT: :[[@LINE+2]]:5: warning: avoid do-while loops
+    int x1{0};
+    do {
+      x1 = baz();
+    } while (x1 > 0);
+
+    // CHECK-MESSAGES-IGNORE-MACROS: :[[@LINE+2]]:5: warning: avoid do-while loops
+    // CHECK-MESSAGES-DEFAULT: :[[@LINE+1]]:5: warning: avoid do-while loops
+    do {
+
+    } while (x1 != 0);
+
+    // CHECK-MESSAGES-IGNORE-MACROS: :[[@LINE+3]]:5: warning: avoid do-while loops
+    // CHECK-MESSAGES-DEFAULT: :[[@LINE+2]]:5: warning: avoid do-while loops
+    constexpr int x2{0};
+    do {
+
+    } while (x2);
+
+    // CHECK-MESSAGES-IGNORE-MACROS: :[[@LINE+3]]:5: warning: avoid do-while loops
+    // CHECK-MESSAGES-DEFAULT: :[[@LINE+2]]:5: warning: avoid do-while loops
+    constexpr bool x3{false};
+    do {
+
+    } while (x3);
+
+    // CHECK-MESSAGES-DEFAULT: :[[@LINE+1]]:5: warning: avoid do-while loops
+    FOO(x1);
+
+    // CHECK-MESSAGES-DEFAULT: :[[@LINE+1]]:5: warning: avoid do-while loops
+    BAR_0(x1);
+
+    // CHECK-MESSAGES-DEFAULT: :[[@LINE+1]]:5: warning: avoid do-while loops
+    BAR_FALSE(x1);
+}