[clang-tidy] bugprone-infinite-loop: React to ObjC ivars and messages.

If the loop condition is a value of an instance variable, a property value,
or a message result value, it's a good indication that the loop is not infinite
and we have a really hard time proving the opposite so suppress the warning.

Differential Revision: https://reviews.llvm.org/D102294

2 files changed, 92 insertions, 1 deletions

diff --git a/clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp b/clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
index ab62b12..8ac7f8e 100644
--- a/clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
+++ b/clang-tools-extra/clang-tidy/bugprone/InfiniteLoopCheck.cpp
@@ -61,7 +61,8 @@ static bool isVarThatIsPossiblyChanged(const Decl *Func, const Stmt *LoopStmt,
              isChanged(LoopStmt, Var, Context);
       // FIXME: Track references.
     }
-  } else if (isa<MemberExpr>(Cond) || isa<CallExpr>(Cond)) {
+  } else if (isa<MemberExpr, CallExpr,
+                 ObjCIvarRefExpr, ObjCPropertyRefExpr, ObjCMessageExpr>(Cond)) {
     // FIXME: Handle MemberExpr.
     return true;
   }
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone-infinite-loop.mm b/clang-tools-extra/test/clang-tidy/checkers/bugprone-infinite-loop.mm
index 77d85ac..8f157b3 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone-infinite-loop.mm
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone-infinite-loop.mm
@@ -1,8 +1,20 @@
 // RUN: %check_clang_tidy %s bugprone-infinite-loop %t -- -- -fblocks
+// RUN: %check_clang_tidy %s bugprone-infinite-loop %t -- -- -fblocks -fobjc-arc
+
+typedef __typeof(sizeof(int)) NSUInteger;
+
+@interface NSArray
++(instancetype)alloc;
+-(instancetype)init;
+@property(readonly) NSUInteger count;
+-(void)addObject: (id)anObject;
+@end
 
 @interface I
 -(void) instanceMethod;
 +(void) classMethod;
++(instancetype)alloc;
+-(instancetype)init;
 @end
 
 void plainCFunction() {
@@ -33,3 +45,81 @@ void plainCFunction() {
   }
 }
 @end
+
+void testArrayCount() {
+  NSArray *arr = [[NSArray alloc] init];
+  NSUInteger max_count = 10;
+  while ([arr count] < max_count) {
+    // No warning. Array count is updated on every iteration.
+    [arr addObject: [[I alloc] init]];
+  }
+}
+
+void testArrayCountWithConstant() {
+  NSArray *arr = [[NSArray alloc] init];
+  while ([arr count] < 10) {
+    // No warning. Array count is updated on every iteration.
+    [arr addObject: [[I alloc] init]];
+  }
+}
+
+void testArrayCountProperty() {
+  NSArray *arr = [[NSArray alloc] init];
+  NSUInteger max_count = 10;
+  while (arr.count < max_count) {
+    // No warning. Array count is updated on every iteration.
+    [arr addObject: [[I alloc] init]];
+  }
+}
+
+void testArrayCountPropertyWithConstant() {
+  NSArray *arr = [[NSArray alloc] init];
+  while (arr.count < 10) {
+    // No warning. Array count is updated on every iteration.
+    [arr addObject: [[I alloc] init]];
+  }
+}
+
+@interface MyArray {
+  @public NSUInteger _count;
+}
++(instancetype)alloc;
+-(instancetype)init;
+-(void)addObject: (id)anObject;
+
+-(void)populate;
+@end
+
+@implementation MyArray
+-(void)populate {
+  NSUInteger max_count = 10;
+  while (_count < max_count) {
+    // No warning. Array count is updated on every iteration.
+    [self addObject: [[I alloc] init]];
+  }
+}
+
+-(void)populateWithConstant {
+  while (_count < 10) {
+    // No warning. Array count is updated on every iteration.
+    [self addObject: [[I alloc] init]];
+  }
+}
+@end
+
+void testArrayCountIvar() {
+  MyArray *arr = [[MyArray alloc] init];
+  NSUInteger max_count = 10;
+  while (arr->_count < max_count) {
+    // No warning. Array count is updated on every iteration.
+    [arr addObject: [[I alloc] init]];
+  }
+}
+
+void testArrayCountIvarWithConstant() {
+  MyArray *arr = [[MyArray alloc] init];
+  while (arr->_count < 10) {
+    // No warning. Array count is updated on every iteration.
+    [arr addObject: [[I alloc] init]];
+  }
+}