[clang-tools-extra] c69ec64 - [clang-tidy] Added check to disable bugprone-infinite-loop on known false condition

[Nathan James via cfe-commits]

Author: Nathan James
Date: 2020-02-11T19:37:11Z
New Revision: c69ec6476806147e46bf09b693acb24177982dc2

URL: https://github.com/llvm/llvm-project/commit/c69ec6476806147e46bf09b693acb24177982dc2
DIFF: https://github.com/llvm/llvm-project/commit/c69ec6476806147e46bf09b693acb24177982dc2.diff

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

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

Reviewers: aaron.ballman, alexfh, hokein, gribozavr2, JonasToth

Reviewed By: gribozavr2

Subscribers: xazax.hun, cfe-commits

Tags: #clang, #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D74374

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
index 5a705376cd4b..00793009ed39 100644
--- a/clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
@@ -152,6 +152,13 @@ static std::string getCondVarNames(const Stmt *Cond) {
   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 @@ void InfiniteLoopCheck::check(const MatchFinder::MatchResult &Result) {
   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()) {

diff  --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone-infinite-loop.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone-infinite-loop.cpp
index d89bdadf0212..427b5f0272b9 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone-infinite-loop.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone-infinite-loop.cpp
@@ -354,3 +354,12 @@ void lambda_capture() {
     (*p)++;
   } while (i < Limit);
 }
+
+void evaluatable(bool CondVar) {
+  for (; false && CondVar;) {
+  }
+  while (false && CondVar) {
+  }
+  do {
+  } while (false && CondVar);
+}