1 files changed, 70 insertions, 0 deletions
diff --git a/clang-tools-extra/clang-tidy/misc/BoolPointerImplicitConversion.cpp b/clang-tools-extra/clang-tidy/misc/BoolPointerImplicitConversion.cpp
new file mode 100644
index 00000000000..6565874a340
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/misc/BoolPointerImplicitConversion.cpp
@@ -0,0 +1,70 @@
+//===--- BoolPointerImplicitConversion.cpp - clang-tidy -------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "BoolPointerImplicitConversion.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace ast_matchers {
+
+AST_MATCHER(CastExpr, isPointerToBoolean) {
+  return Node.getCastKind() == CK_PointerToBoolean;
+}
+AST_MATCHER(QualType, isBoolean) { return Node->isBooleanType(); }
+
+} // namespace ast_matchers
+
+namespace tidy {
+
+void BoolPointerImplicitConversion::registerMatchers(MatchFinder *Finder) {
+  // Look for ifs that have an implicit bool* to bool conversion in the
+  // condition. Filter negations.
+  Finder->addMatcher(
+      ifStmt(hasCondition(findAll(implicitCastExpr(
+                 allOf(unless(hasParent(unaryOperator(hasOperatorName("!")))),
+                       hasSourceExpression(expr(
+                           hasType(pointerType(pointee(isBoolean()))),
+                           ignoringParenImpCasts(declRefExpr().bind("expr")))),
+                       isPointerToBoolean()))))).bind("if"),
+      this);
+}
+
+void
+BoolPointerImplicitConversion::check(const MatchFinder::MatchResult &Result) {
+  auto *If = Result.Nodes.getStmtAs<IfStmt>("if");
+  auto *Var = Result.Nodes.getStmtAs<DeclRefExpr>("expr");
+
+  // Only allow variable accesses for now, no function calls or member exprs.
+  // Check that we don't dereference the variable anywhere within the if. This
+  // avoids false positives for checks of the pointer for nullptr before it is
+  // dereferenced. If there is a dereferencing operator on this variable don't
+  // emit a diagnostic. Also ignore array subscripts.
+  const Decl *D = Var->getDecl();
+  auto DeclRef = ignoringParenImpCasts(declRefExpr(to(equalsNode(D))));
+  if (!match(findAll(
+                 unaryOperator(hasOperatorName("*"), hasUnaryOperand(DeclRef))),
+             *If, *Result.Context).empty() ||
+      !match(findAll(arraySubscriptExpr(hasBase(DeclRef))), *If,
+             *Result.Context).empty() ||
+      // FIXME: We should still warn if the paremater is implicitly converted to
+      // bool.
+      !match(findAll(callExpr(hasAnyArgument(DeclRef))), *If, *Result.Context)
+           .empty() ||
+      !match(findAll(deleteExpr(has(expr(DeclRef)))), *If, *Result.Context)
+           .empty())
+    return;
+
+  diag(Var->getLocStart(), "dubious check of 'bool *' against 'nullptr', did "
+                           "you mean to dereference it?")
+      << FixItHint::CreateInsertion(Var->getLocStart(), "*");
+}
+
+} // namespace tidy
+} // namespace clang