[clang-tidy] New bugprone-infinite-loop check for detecting obvious infinite loops

Finding infinite loops is well-known to be impossible (halting problem).
However, it is possible to detect some obvious infinite loops, for example,
if the loop condition is not changed. Detecting such loops is beneficial
since the tests will hang on programs containing infinite loops so
testing-time detection may be costly in large systems. Obvious cases are
where the programmer forgets to increment/decrement the counter or
increments/decrements the wrong variable.

Differential Revision: https://reviews.llvm.org/D64736

llvm-svn: 372693

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

@@ -23,6 +23,7 @@
 #include "ForwardingReferenceOverloadCheck.h"
 #include "InaccurateEraseCheck.h"
 #include "IncorrectRoundingsCheck.h"
+#include "InfiniteLoopCheck.h"
 #include "IntegerDivisionCheck.h"
 #include "LambdaFunctionNameCheck.h"
 #include "MacroParenthesesCheck.h"
@@ -88,6 +89,8 @@ public:
         "bugprone-inaccurate-erase");
     CheckFactories.registerCheck<IncorrectRoundingsCheck>(
         "bugprone-incorrect-roundings");
+    CheckFactories.registerCheck<InfiniteLoopCheck>(
+        "bugprone-infinite-loop");
     CheckFactories.registerCheck<IntegerDivisionCheck>(
         "bugprone-integer-division");
     CheckFactories.registerCheck<LambdaFunctionNameCheck>(

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

@@ -15,6 +15,7 @@ add_clang_library(clangTidyBugproneModule
   ForwardingReferenceOverloadCheck.cpp
   InaccurateEraseCheck.cpp
   IncorrectRoundingsCheck.cpp
+  InfiniteLoopCheck.cpp
   IntegerDivisionCheck.cpp
   LambdaFunctionNameCheck.cpp
   MacroParenthesesCheck.cpp

clang-tools-extra/docs/ReleaseNotes.rst

@@ -70,6 +70,86 @@ Improvements to clang-tidy
 - New :doc:`bugprone-dynamic-static-initializers
   <clang-tidy/checks/bugprone-dynamic-static-initializers>` check.
 
+- New OpenMP module.
+
+  For checks specific to `OpenMP <https://www.openmp.org/>`_ API.
+
+- New :doc:`abseil-duration-addition
+  <clang-tidy/checks/abseil-duration-addition>` check.
+
+  Checks for cases where addition should be performed in the ``absl::Time``
+  domain.
+
+- New :doc:`abseil-duration-conversion-cast
+  <clang-tidy/checks/abseil-duration-conversion-cast>` check.
+
+  Checks for casts of ``absl::Duration`` conversion functions, and recommends
+  the right conversion function instead.
+
+- New :doc:`abseil-duration-unnecessary-conversion
+  <clang-tidy/checks/abseil-duration-unnecessary-conversion>` check.
+
+  Finds and fixes cases where ``absl::Duration`` values are being converted to
+  numeric types and back again.
+
+- New :doc:`abseil-time-comparison
+  <clang-tidy/checks/abseil-time-comparison>` check.
+
+  Prefer comparisons in the ``absl::Time`` domain instead of the integer
+  domain.
+
+- New :doc:`abseil-time-subtraction
+  <clang-tidy/checks/abseil-time-subtraction>` check.
+
+  Finds and fixes ``absl::Time`` subtraction expressions to do subtraction
+  in the Time domain instead of the numeric domain.
+
+- New :doc:`android-cloexec-pipe
+  <clang-tidy/checks/android-cloexec-pipe>` check.
+
+  This check detects usage of ``pipe()``.
+
+- New :doc:`android-cloexec-pipe2
+  <clang-tidy/checks/android-cloexec-pipe2>` check.
+
+  This checks ensures that ``pipe2()`` is called with the O_CLOEXEC flag.
+
+- New :doc:`bugprone-infinite-loop
+  <clang-tidy/checks/bugprone-infinite-loop>` check.
+
+  Finds obvious infinite loops (loops where the condition variable is not
+  changed at all).
+
+- New :doc:`bugprone-unhandled-self-assignment
+  <clang-tidy/checks/bugprone-unhandled-self-assignment>` check.
+
+  Finds user-defined copy assignment operators which do not protect the code
+  against self-assignment either by checking self-assignment explicitly or
+  using the copy-and-swap or the copy-and-move method.
+
+- New :doc:`bugprone-branch-clone
+  <clang-tidy/checks/bugprone-branch-clone>` check.
+
+  Checks for repeated branches in ``if/else if/else`` chains, consecutive
+  repeated branches in ``switch`` statements and indentical true and false
+  branches in conditional operators.
+
+- New :doc:`bugprone-posix-return
+  <clang-tidy/checks/bugprone-posix-return>` check.
+
+  Checks if any calls to POSIX functions (except ``posix_openpt``) expect negative
+  return values.
+
+- New :doc:`fuchsia-default-arguments-calls
+  <clang-tidy/checks/fuchsia-default-arguments-calls>` check.
+
+  Warns if a function or method is called with default arguments.
+  This was previously done by `fuchsia-default-arguments check`, which has been
+  removed.
+
+- New :doc:`fuchsia-default-arguments-calls
+  <clang-tidy/checks/fuchsia-default-arguments-calls>` check.
+
   Finds instances where variables with static storage are initialized
   dynamically in header files.
 
@@ -103,6 +183,10 @@ Improvements to clang-tidy
   Now also checks if any calls to ``pthread_*`` functions expect negative return
   values.
 
+- New :doc:`bugprone-infinite-loop <clang-tidy/checks/bugprone-infinite-loop>`
+  check to detect obvious infinite loops (loops where the condition variable is
+  not changed at all).
+
 Improvements to include-fixer
 -----------------------------
 

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

@@ -51,6 +51,7 @@ Clang-Tidy Checks
    bugprone-forwarding-reference-overload
    bugprone-inaccurate-erase
    bugprone-incorrect-roundings
+   bugprone-infinite-loop
    bugprone-integer-division
    bugprone-lambda-function-name
    bugprone-macro-parentheses