[PATCH] D74374: [clang-tidy] Added check to disable bugprone-infinite-loop on known false condition

[Nathan James via Phabricator via cfe-commits]

njames93 created this revision.
Herald added subscribers: cfe-commits, xazax.hun.
Herald added a project: clang.
njames93 edited the summary of this revision.
njames93 added reviewers: aaron.ballman, alexfh, hokein, gribozavr2, JonasToth.
njames93 added a project: clang-tools-extra.

Addresses bugprone-infinite-loop false positive with CATCH2 <https://bugs.llvm.org/show_bug.cgi?id=44816> by disabling the check on loops where the condition is known to always eval as false, in other words not a loop.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D74374

Files:
  clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
  clang-tools-extra/test/clang-tidy/checkers/bugprone-infinite-loop.cpp


Index: clang-tools-extra/test/clang-tidy/checkers/bugprone-infinite-loop.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/bugprone-infinite-loop.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/bugprone-infinite-loop.cpp
@@ -354,3 +354,12 @@
     (*p)++;
   } while (i < Limit);
 }
+
+void evaluatable(bool CondVar) {
+  for (; false && CondVar;) {
+  }
+  while (false && CondVar) {
+  }
+  do {
+  } while (false && CondVar);
+}
Index: clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
+++ clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
@@ -152,6 +152,13 @@
   return Result;
 }
 
+static bool isKnownFalse(const Expr &Cond, const ASTContext &Ctx) {
+  bool Result = false;
+  if (Cond.EvaluateAsBooleanCondition(Result, Ctx))
+    return !Result;
+  return false;
+}
+
 void InfiniteLoopCheck::registerMatchers(MatchFinder *Finder) {
   const auto LoopCondition = allOf(
       hasCondition(
@@ -170,6 +177,9 @@
   const auto *LoopStmt = Result.Nodes.getNodeAs<Stmt>("loop-stmt");
   const auto *Func = Result.Nodes.getNodeAs<FunctionDecl>("func");
 
+  if (isKnownFalse(*Cond, *Result.Context))
+    return;
+
   bool ShouldHaveConditionVariables = true;
   if (const auto *While = dyn_cast<WhileStmt>(LoopStmt)) {
     if (const VarDecl *LoopVarDecl = While->getConditionVariable()) {


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D74374.243712.patch
Type: text/x-patch
Size: 1517 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20200211/f0dd7eb2/attachment.bin>