[clang-tidy] Adds the NSDateFormatter checker to clang-tidy

[t-rasmud]

Summary

Reports incorrect string patterns in the date format specifier.

[NoQ]

Looks awesome!

add_new_check.py

I'm surprised it wasn't executable already, do we want to keep it?

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

13

Looks like everybody's respecting CaPiTaLiZaTiOn, I guess we could too?

clang-tools-extra/clang-tidy/objc/NsdateformatterCheck.cpp

22 ↗

(On Diff #431076)

Please clang-format this down to 80 column limit (https://llvm.org/docs/CodingStandards.html).

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

38–39

Where did these go?

[Eugene.Zelenko]

clang-tools-extra/clang-tidy/objc/NsdateformatterCheck.cpp

12 ↗

(On Diff #431076)

cctype? See modernize-deprecated-headers.

30 ↗

(On Diff #431076)

Range loop? See modernize-loop-convert.

clang-tools-extra/clang-tidy/objc/NsdateformatterCheck.h

29 ↗

(On Diff #431076)

Please add isLanguageVersionSupported.

clang-tools-extra/clang-tidy/objc/ObjCTidyModule.cpp

32

I think all check names are lowercase.

34

Excessive newline.

clang-tools-extra/docs/clang-tidy/checks/objc-NSDateFormatter.rst

5 ↗

(On Diff #431076)

Please separate with newline.

10 ↗

(On Diff #431076)

Please enclose all examples and formats into single back-ticks.

[njames93]

In D126097#3528787, @NoQ wrote:

Looks awesome!

add_new_check.py

I'm surprised it wasn't executable already, do we want to keep it?

It keeps getting reset, likely due to Windows users committing changes. It should be executable but the change shouldn't be made in this patch

clang-tools-extra/clang-tidy/objc/NsdateformatterCheck.cpp

22 ↗

(On Diff #431076)

hasDescendant seems dangerous here. I'm no ObjC expert, but I'm guessing the argument could be a function call, in which case you could match an argument of that nested functionCall that's a StringLiteral.

28 ↗

(On Diff #431076)

I'm pretty sure StringRef has a method that does this for you, contains I think it's called.

clang-tools-extra/clang-tidy/objc/ObjCTidyModule.cpp

19

File names for checks should be in CamelCaseFormat.

32

Yeah, I'd suggest objc-nsdate-formatter

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

38–39

This is a unintended change from the add_new_check script. It should be reverted here tho.

clang-tools-extra/test/clang-tidy/checkers/objc-NSDateFormatter.m

3 ↗

(On Diff #431076)

Again no expert on ObjC, but test files have no system headers so where does this file live?

[LegalizeAdulthood]

Clang-Tidy tests and docs have moved to module subdirectories.

Please rebase this onto main:HEAD and:

• fold your changes into the appropriate subdirs, stripping the module prefix from new files.
• make the target check-clang-extra to validate your tests
• make the target docs-clang-tools-html to validate any docs changes

[t-rasmud]

Addresses review comments from the previously uploaded diff.

[t-rasmud]

Ping

[NoQ]

Uh-oh sorry! I have a couple more questions and then we can probably land.

clang-tools-extra/clang-tidy/objc/NSDateFormatterCheck.cpp

25

Can or should we check the class name as well? It's probably going to be pretty rare that people have a method with the same name, that also accepts the first argument as a string literal, but that literal means something else entirely. However there's little reason not to be more cautious about that.

68–69

I think we want spaces in such cases. I'm not sure, discussion welcome.

[NoQ]

Great, thanks! Unless there are other objections from other reviewers, I think this is good to go.

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

 set(LLVM_LINK_COMPONENTS
   FrontendOpenMP
   Support
   )
 
 add_clang_library(clangTidyObjCModule
   AssertEquals.cpp
   AvoidNSErrorInitCheck.cpp
   DeallocInCategoryCheck.cpp
   ForbiddenSubclassingCheck.cpp
   MissingHashCheck.cpp
   NSInvocationArgumentLifetimeCheck.cpp
+  NSDateFormatterCheck.cpp
   ObjCTidyModule.cpp
   PropertyDeclarationCheck.cpp
   SuperSelfCheck.cpp
 
   LINK_LIBS
   clangTidy
   clangTidyUtils
 

clang-tools-extra/clang-tidy/objc/NSDateFormatterCheck.h

+//===--- NSDateFormatterCheck.h - clang-tidy --------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_OBJC_NSDATEFORMATTERCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_OBJC_NSDATEFORMATTERCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang {
+namespace tidy {
+namespace objc {
+
+/// Checks the string pattern used as a date format specifier and reports
+/// warnings if it contains any incorrect sub-pattern.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/objc-NSDateFormatter.html
+class NSDateFormatterCheck : public ClangTidyCheck {
+public:
+  NSDateFormatterCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+    return LangOpts.ObjC;
+  }
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace objc
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_OBJC_NSDATEFORMATTERCHECK_H

clang-tools-extra/clang-tidy/objc/NSDateFormatterCheck.cpp

+//===--- NSDateFormatterCheck.cpp - clang-tidy ----------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "NSDateFormatterCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace objc {
+
+void NSDateFormatterCheck::registerMatchers(MatchFinder *Finder) {
+  // Adding matchers.
+
+  Finder->addMatcher(
+      objcMessageExpr(hasSelector("setDateFormat:"),
+                      hasReceiverType(asString("NSDateFormatter *")),
+                      hasArgument(0, ignoringImpCasts(
+                                         objcStringLiteral().bind("str_lit")))),
+      this);
+}
+
+static char ValidDatePatternChars[] = {
+    'G', 'y', 'Y', 'u', 'U', 'r', 'Q', 'q', 'M', 'L', 'I', 'w', 'W', 'd',
+    'D', 'F', 'g', 'E', 'e', 'c', 'a', 'b', 'B', 'h', 'H', 'K', 'k', 'j',
+    'J', 'C', 'm', 's', 'S', 'A', 'z', 'Z', 'O', 'v', 'V', 'X', 'x'};
+
+// Checks if the string pattern used as a date format specifier is valid.
+// A string pattern is valid if all the letters(a-z, A-Z) in it belong to the
+// set of reserved characters. See:
+// https://www.unicode.org/reports/tr35/tr35.html#Invalid_Patterns
+bool isValidDatePattern(StringRef Pattern) {
+  for (auto &PatternChar : Pattern) {
+    if (isalpha(PatternChar)) {
+      if (std::find(std::begin(ValidDatePatternChars),
+                    std::end(ValidDatePatternChars),
+                    PatternChar) == std::end(ValidDatePatternChars)) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+// Checks if the string pattern used as a date format specifier contains
+// any incorrect pattern and reports it as a warning.
+// See: http://www.unicode.org/reports/tr35/tr35-dates.html#Date_Format_Patterns
+void NSDateFormatterCheck::check(const MatchFinder::MatchResult &Result) {
+  // Callback implementation.
+  const auto *StrExpr = Result.Nodes.getNodeAs<ObjCStringLiteral>("str_lit");
+  const StringLiteral *SL = cast<ObjCStringLiteral>(StrExpr)->getString();
+  StringRef SR = SL->getString();
+
+  if (!isValidDatePattern(SR)) {
+    diag(StrExpr->getExprLoc(), "invalid date format specifier");
+  }
+
+  if (SR.contains('y') && SR.contains('w') && !SR.contains('Y')) {
+    diag(StrExpr->getExprLoc(),
+         "use of calendar year (y) with week of the year (w); "
+         "did you mean to use week-year (Y) instead?");
+  }
+  if (SR.contains('F')) {
+    if (!(SR.contains('e') || SR.contains('E'))) {
+      diag(StrExpr->getExprLoc(),
+           "day of week in month (F) used without day of the week (e or E); "
+           "did you forget e (or E) in the format string?");
+    }
+    if (!SR.contains('M')) {
+      diag(StrExpr->getExprLoc(),
+           "day of week in month (F) used without the month (M); "
+           "did you forget M in the format string?");
+    }
+  }
+  if (SR.contains('W') && !SR.contains('M')) {
+    diag(StrExpr->getExprLoc(), "Week of Month (W) used without the month (M); "
+                                "did you forget M in the format string?");
+  }
+  if (SR.contains('Y') && SR.contains('Q') && !SR.contains('y')) {
+    diag(StrExpr->getExprLoc(),
+         "use of week year (Y) with quarter number (Q); "
+         "did you mean to use calendar year (y) instead?");
+  }
+  if (SR.contains('Y') && SR.contains('M') && !SR.contains('y')) {
+    diag(StrExpr->getExprLoc(),
+         "use of week year (Y) with month (M); "
+         "did you mean to use calendar year (y) instead?");
+  }
+  if (SR.contains('Y') && SR.contains('D') && !SR.contains('y')) {
+    diag(StrExpr->getExprLoc(),
+         "use of week year (Y) with day of the year (D); "
+         "did you mean to use calendar year (y) instead?");
+  }
+  if (SR.contains('Y') && SR.contains('W') && !SR.contains('y')) {
+    diag(StrExpr->getExprLoc(),
+         "use of week year (Y) with week of the month (W); "
+         "did you mean to use calendar year (y) instead?");
+  }
+  if (SR.contains('Y') && SR.contains('F') && !SR.contains('y')) {
+    diag(StrExpr->getExprLoc(),
+         "use of week year (Y) with day of the week in month (F); "
+         "did you mean to use calendar year (y) instead?");
+  }
+}
+
+} // namespace objc
+} // namespace tidy
+} // namespace clang

clang-tools-extra/clang-tidy/objc/ObjCTidyModule.cpp

 //===--- ObjCTidyModule.cpp - clang-tidy --------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "../ClangTidy.h"
 #include "../ClangTidyModule.h"
 #include "../ClangTidyModuleRegistry.h"
 #include "AssertEquals.h"
 #include "AvoidNSErrorInitCheck.h"
 #include "DeallocInCategoryCheck.h"
 #include "ForbiddenSubclassingCheck.h"
 #include "MissingHashCheck.h"
+#include "NSDateFormatterCheck.h"
 #include "NSInvocationArgumentLifetimeCheck.h"
 #include "PropertyDeclarationCheck.h"
 #include "SuperSelfCheck.h"
 
 using namespace clang::ast_matchers;
 
 namespace clang {
 namespace tidy {
 namespace objc {
 
 class ObjCModule : public ClangTidyModule {
 public:
   void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
     CheckFactories.registerCheck<AvoidNSErrorInitCheck>(
         "objc-avoid-nserror-init");
     CheckFactories.registerCheck<AssertEquals>("objc-assert-equals");
 
     CheckFactories.registerCheck<DeallocInCategoryCheck>(
         "objc-dealloc-in-category");
     CheckFactories.registerCheck<ForbiddenSubclassingCheck>(
         "objc-forbidden-subclassing");
     CheckFactories.registerCheck<MissingHashCheck>(
         "objc-missing-hash");
+    CheckFactories.registerCheck<NSDateFormatterCheck>("objc-nsdate-formatter");
     CheckFactories.registerCheck<NSInvocationArgumentLifetimeCheck>(
         "objc-nsinvocation-argument-lifetime");
     CheckFactories.registerCheck<PropertyDeclarationCheck>(
         "objc-property-declaration");
     CheckFactories.registerCheck<SuperSelfCheck>(
         "objc-super-self");
   }
 };

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

.. toctree::
    openmp/*
    performance/*
    portability/*
    readability/*
    zircon/*
 
 .. csv-table::
    :header: "Name", "Offers fixes"
 
    `abseil-cleanup-ctad <abseil/cleanup-ctad.html>`_, "Yes"
    `abseil-duration-addition <abseil/duration-addition.html>`_, "Yes"
    `abseil-duration-comparison <abseil/duration-comparison.html>`_, "Yes"
    `abseil-duration-conversion-cast <abseil/duration-conversion-cast.html>`_, "Yes"
    `abseil-duration-division <abseil/duration-division.html>`_, "Yes"
    `abseil-duration-factory-float <abseil/duration-factory-float.html>`_, "Yes"
    `abseil-duration-factory-scale <abseil/duration-factory-scale.html>`_, "Yes"
    `abseil-duration-subtraction <abseil/duration-subtraction.html>`_, "Yes"
    `abseil-duration-unnecessary-conversion <abseil/duration-unnecessary-conversion.html>`_, "Yes"
.. csv-table::
    `llvm-namespace-comment <llvm/namespace-comment.html>`_,
    `llvm-prefer-isa-or-dyn-cast-in-conditionals <llvm/prefer-isa-or-dyn-cast-in-conditionals.html>`_, "Yes"
    `llvm-prefer-register-over-unsigned <llvm/prefer-register-over-unsigned.html>`_, "Yes"
    `llvm-twine-local <llvm/twine-local.html>`_, "Yes"
    `llvmlibc-callee-namespace <llvmlibc/callee-namespace.html>`_,
    `llvmlibc-implementation-in-namespace <llvmlibc/implementation-in-namespace.html>`_,
    `llvmlibc-restrict-system-libc-headers <llvmlibc/restrict-system-libc-headers.html>`_, "Yes"
    `misc-confusable-identifiers <misc/confusable-identifiers.html>`_,
-   `misc-const-correctness <misc/const-correctness.html>`_, "Yes"
    `misc-definitions-in-headers <misc/definitions-in-headers.html>`_, "Yes"
    `misc-misleading-bidirectional <misc/misleading-bidirectional.html>`_,
    `misc-misleading-identifier <misc/misleading-identifier.html>`_,
    `misc-misplaced-const <misc/misplaced-const.html>`_,
    `misc-new-delete-overloads <misc/new-delete-overloads.html>`_,
    `misc-no-recursion <misc/no-recursion.html>`_,
    `misc-non-copyable-objects <misc/non-copyable-objects.html>`_,
    `misc-non-private-member-variables-in-classes <misc/non-private-member-variables-in-classes.html>`_,
.. csv-table::
    `modernize-use-using <modernize/use-using.html>`_, "Yes"
    `mpi-buffer-deref <mpi/buffer-deref.html>`_, "Yes"
    `mpi-type-mismatch <mpi/type-mismatch.html>`_, "Yes"
    `objc-assert-equals <objc/assert-equals.html>`_, "Yes"
    `objc-avoid-nserror-init <objc/avoid-nserror-init.html>`_,
    `objc-dealloc-in-category <objc/dealloc-in-category.html>`_,
    `objc-forbidden-subclassing <objc/forbidden-subclassing.html>`_,
    `objc-missing-hash <objc/missing-hash.html>`_,
+   `objc-nsdate-formatter <objc/nsdate-formatter.html>`_,
    `objc-nsinvocation-argument-lifetime <objc/nsinvocation-argument-lifetime.html>`_, "Yes"
    `objc-property-declaration <objc/property-declaration.html>`_, "Yes"
    `objc-super-self <objc/super-self.html>`_, "Yes"
    `openmp-exception-escape <openmp/exception-escape.html>`_,
    `openmp-use-default-none <openmp/use-default-none.html>`_,
    `performance-faster-string-find <performance/faster-string-find.html>`_, "Yes"
    `performance-for-range-copy <performance/for-range-copy.html>`_, "Yes"
    `performance-implicit-conversion-in-loop <performance/implicit-conversion-in-loop.html>`_,

clang-tools-extra/docs/clang-tidy/checks/objc/nsdate-formatter.rst

+.. title:: clang-tidy - objc-nsdate-formatter
+
+objc-nsdate-formatter
+=====================
+
+When ``NSDateFormatter`` is used to convert an ``NSDate`` type to a ``String`` type, the user
+can specify a custom format string. Certain format specifiers are undesirable
+despite being legal. See http://www.unicode.org/reports/tr35/tr35-dates.html#Date_Format_Patterns for all legal date patterns.
+
+This checker reports as warnings the following string patterns in a date format specifier:
+
+#. yyyy + ww : Calendar year specified with week of a week year (unless YYYY is also specified).
+  
+   * | **Example 1:** Input Date: `29 December 2014` ; Format String: `yyyy-ww`; 
+     | Output string: `2014-01` (Wrong because it’s not the first week of 2014)
+    
+   * | **Example 2:** Input Date: `29 December 2014` ; Format String: `dd-MM-yyyy (ww-YYYY)`; 
+     | Output string: `29-12-2014 (01-2015)` (This is correct)
+    
+#. F without ee/EE : Numeric day of week in a month without actual day.
+    
+   * | **Example:** Input Date: `29 December 2014` ; Format String: `F-MM`; 
+     | Output string: `5-12` (Wrong because it reads as *5th ___ of Dec* in English)
+    
+#. F without MM : Numeric day of week in a month without month.
+   
+   * | **Example:** Input Date: `29 December 2014` ; Format String: `F-EE`
+     | Output string: `5-Mon` (Wrong because it reads as *5th Mon of ___* in English)
+    
+#. WW without MM : Week of the month without the month.
+   
+   * | **Example:** Input Date: `29 December 2014` ; Format String: `WW-yyyy`
+     | Output string: `05-2014` (Wrong because it reads as *5th Week of ___* in English)
+    
+#. YYYY + QQ : Week year specified with quarter of normal year (unless yyyy is also specified).
+   
+   * | **Example 1:** Input Date: `29 December 2014` ; Format String: `YYYY-QQ`
+     | Output string: `2015-04` (Wrong because it’s not the 4th quarter of 2015)
+    
+   * | **Example 2:** Input Date: `29 December 2014` ; Format String: `ww-YYYY (QQ-yyyy)`
+     | Output string: `01-2015 (04-2014)` (This is correct)
+    
+#. YYYY + MM :  Week year specified with Month of a calendar year (unless yyyy is also specified).
+    
+   * | **Example 1:** Input Date: `29 December 2014` ; Format String: `YYYY-MM`
+     | Output string: `2015-12` (Wrong because it’s not the 12th month of 2015)
+    
+   * | **Example 2:** Input Date: `29 December 2014` ; Format String: `ww-YYYY (MM-yyyy)`
+     | Output string: `01-2015 (12-2014)` (This is correct)
+    
+#. YYYY + DD : Week year with day of a calendar year (unless yyyy is also specified).
+    
+   * | **Example 1:** Input Date: `29 December 2014` ; Format String: `YYYY-DD`
+     | Output string: `2015-363` (Wrong because it’s not the 363rd day of 2015)
+    
+   * | **Example 2:** Input Date: `29 December 2014` ; Format String: `ww-YYYY (DD-yyyy)`
+     | Output string: `01-2015 (363-2014)` (This is correct)
+    
+#. YYYY + WW : Week year with week of a calendar year (unless yyyy is also specified).
+    
+   * | **Example 1:** Input Date: `29 December 2014` ; Format String: `YYYY-WW`
+     | Output string: `2015-05` (Wrong because it’s not the 5th week of 2015)
+    
+   * | **Example 2:** Input Date: `29 December 2014` ; Format String: `ww-YYYY (WW-MM-yyyy)`
+     | Output string: `01-2015 (05-12-2014)` (This is correct)
+    
+#. YYYY + F : Week year with day of week in a calendar month (unless yyyy is also specified).
+    
+   * | **Example 1:** Input Date: `29 December 2014` ; Format String: `YYYY-ww-F-EE`
+     | Output string: `2015-01-5-Mon` (Wrong because it’s not the 5th Monday of January in 2015)
+    
+   * | **Example 2:** Input Date: `29 December 2014` ; Format String: `ww-YYYY (F-EE-MM-yyyy)`
+     | Output string: `01-2015 (5-Mon-12-2014)` (This is correct)

clang-tools-extra/test/clang-tidy/checkers/objc/nsdate-formatter.m

+// RUN: %check_clang_tidy %s objc-nsdate-formatter %t
+@interface NSObject
++ (instancetype)alloc;
+- (instancetype)init;
+@end
+
+@interface TestClass : NSObject
++ (void)testMethod1;
++ (void)testMethod2;
++ (void)testMethod3;
++ (void)testAnotherClass;
+@end
+
+@interface NSString : NSObject
+@end
+
+void NSLog(NSString *format, ...);
+
+@interface NSDate : NSObject
+@end
+
+@interface NSDateFormatter : NSObject
+@property(copy) NSString *dateFormat;
+- (NSString *)stringFromDate:(NSDate *)date;
+@end
+
+@interface AnotherClass : NSObject
+@property(copy) NSString *dateFormat;
+@end
+
+@interface NSDateComponents : NSObject
+@property long year;
+@property long month;
+@property long day;
+@end
+
+@interface NSCalendar : NSObject
+@property(class, readonly, copy) NSCalendar *currentCalendar;
+- (nullable NSDate *)dateFromComponents:(NSDateComponents *)Comps;
+@end
+
+@implementation TestClass
++ (void)testMethod1 {
+  // Reproducing incorrect behavior from Radar
+  NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
+  [formatter setDateFormat:@"YYYY_MM_dd_HH_mm_ss_SSS_ZZZ"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSDateComponents *comps = [[NSDateComponents alloc] init];
+  [comps setDay:29];
+  [comps setMonth:12];
+  [comps setYear:2014];
+  NSDate *date_radar = [[NSCalendar currentCalendar] dateFromComponents:comps];
+  NSLog(@"YYYY_MM_dd_HH_mm_ss_SSS_ZZZ %@", [formatter stringFromDate:date_radar]);
+
+  // Radar correct behavior
+  [formatter setDateFormat:@"yyyy_MM_dd_HH_mm_ss_SSS_ZZZ"];
+  NSLog(@"yyyy_MM_dd_HH_mm_ss_SSS_ZZZ %@", [formatter stringFromDate:date_radar]);
+
+  // Radar correct behavior - week year
+  [formatter setDateFormat:@"YYYY_ww_dd_HH_mm_ss_SSS_ZZZ"];
+  NSLog(@"YYYY_ww_dd_HH_mm_ss_SSS_ZZZ %@", [formatter stringFromDate:date_radar]);
+
+  // Radar incorrect behavior
+  [formatter setDateFormat:@"yyyy_ww_dd_HH_mm_ss_SSS_ZZZ"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of calendar year (y) with week of the year (w); did you mean to use week-year (Y) instead? [objc-nsdate-formatter]
+  NSLog(@"yyyy_ww_dd_HH_mm_ss_SSS_ZZZ %@", [formatter stringFromDate:date_radar]);
+
+  NSLog(@"==========================================");
+  // Correct
+  [formatter setDateFormat:@"yyyy_MM"];
+  NSLog(@"yyyy_MM %@", [formatter stringFromDate:date_radar]);
+
+  // Correct
+  [formatter setDateFormat:@"yyyy_dd"];
+  NSLog(@"yyyy_dd %@", [formatter stringFromDate:date_radar]);
+
+  // Correct
+  [formatter setDateFormat:@"yyyy_DD"];
+  NSLog(@"yyyy_DD %@", [formatter stringFromDate:date_radar]);
+
+  // Incorrect
+  [formatter setDateFormat:@"yyyy_ww"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of calendar year (y) with week of the year (w); did you mean to use week-year (Y) instead? [objc-nsdate-formatter]
+  NSLog(@"yyyy_ww %@", [formatter stringFromDate:date_radar]);
+
+  // Incorrect
+  [formatter setDateFormat:@"yyyy_WW"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: Week of Month (W) used without the month (M); did you forget M in the format string? [objc-nsdate-formatter]
+  NSLog(@"yyyy_WW %@", [formatter stringFromDate:date_radar]);
+
+  NSLog(@"==========================================");
+  // Correct
+  [formatter setDateFormat:@"yyyy_MM_dd"];
+  NSLog(@"yyyy_MM_dd %@", [formatter stringFromDate:date_radar]);
+
+  // Potentially Incorrect
+  [formatter setDateFormat:@"yyyy_MM_DD"];
+  NSLog(@"yyyy_MM_DD %@", [formatter stringFromDate:date_radar]);
+
+  // Incorrect
+  [formatter setDateFormat:@"yyyy_MM_ww"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of calendar year (y) with week of the year (w); did you mean to use week-year (Y) instead? [objc-nsdate-formatter]
+  NSLog(@"yyyy_MM_ww %@", [formatter stringFromDate:date_radar]);
+
+  NSLog(@"=======WEEK YEAR==========");
+  // Incorrect
+  [formatter setDateFormat:@"YYYY_MM"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_MM %@", [formatter stringFromDate:date_radar]);
+
+  // Correct
+  [formatter setDateFormat:@"YYYY_ww"];
+  NSLog(@"YYYY_ww %@", [formatter stringFromDate:date_radar]);
+
+  // Incorrect
+  [formatter setDateFormat:@"YYYY_WW"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: Week of Month (W) used without the month (M); did you forget M in the format string? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-2]]:28: warning: use of week year (Y) with week of the month (W); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_WW %@", [formatter stringFromDate:date_radar]);
+
+  // Correct
+  [formatter setDateFormat:@"YYYY_dd"];
+  NSLog(@"YYYY_dd %@", [formatter stringFromDate:date_radar]);
+
+  // Incorrect
+  [formatter setDateFormat:@"YYYY_DD"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with day of the year (D); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_DD %@", [formatter stringFromDate:date_radar]);
+
+  NSLog(@"==========================================");
+  // Potentially Incorrect
+  [formatter setDateFormat:@"YYYY_ww_dd"];
+  NSLog(@"YYYY ww dd %@", [formatter stringFromDate:date_radar]);
+
+  // Incorrect
+  [formatter setDateFormat:@"YYYY_ww_DD"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with day of the year (D); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_ww_DD %@", [formatter stringFromDate:date_radar]);
+}
+
++ (void)testMethod2 {
+  NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
+  NSDateComponents *comps = [[NSDateComponents alloc] init];
+  [comps setDay:29];
+  [comps setMonth:12];
+  [comps setYear:2014];
+  NSDate *date_radar = [[NSCalendar currentCalendar] dateFromComponents:comps];
+
+  // Test 1 : incorrect
+  [formatter setDateFormat:@"yyyy_QQ_MM_ww_dd_EE"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of calendar year (y) with week of the year (w); did you mean to use week-year (Y) instead? [objc-nsdate-formatter]
+  NSLog(@"yyyy_QQ_MM_ww_dd_EE %@", [formatter stringFromDate:date_radar]);
+
+  // Test 2 : incorrect
+  [formatter setDateFormat:@"yyyy_QQ_MM_ww_dd_ee"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of calendar year (y) with week of the year (w); did you mean to use week-year (Y) instead? [objc-nsdate-formatter]
+  NSLog(@"yyyy_QQ_MM_ww_dd_ee %@", [formatter stringFromDate:date_radar]);
+
+  // Test 3 : incorrect
+  [formatter setDateFormat:@"yyyy_QQ_MM_ww_DD_EE"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of calendar year (y) with week of the year (w); did you mean to use week-year (Y) instead? [objc-nsdate-formatter]
+  NSLog(@"yyyy_QQ_MM_ww_DD_EE %@", [formatter stringFromDate:date_radar]);
+
+  // Test 4 : incorrect
+  [formatter setDateFormat:@"yyyy_QQ_MM_ww_DD_ee"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of calendar year (y) with week of the year (w); did you mean to use week-year (Y) instead? [objc-nsdate-formatter]
+  NSLog(@"yyyy_QQ_MM_ww_DD_ee %@", [formatter stringFromDate:date_radar]);
+
+  // Test 5 : incorrect
+  [formatter setDateFormat:@"yyyy_QQ_MM_ww_F_EE"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of calendar year (y) with week of the year (w); did you mean to use week-year (Y) instead? [objc-nsdate-formatter]
+  NSLog(@"yyyy_QQ_MM_ww_F_EE %@", [formatter stringFromDate:date_radar]);
+
+  // Test 6 : incorrect
+  [formatter setDateFormat:@"yyyy_QQ_MM_ww_F_ee"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of calendar year (y) with week of the year (w); did you mean to use week-year (Y) instead? [objc-nsdate-formatter]
+  NSLog(@"yyyy_QQ_MM_ww_F_ee %@", [formatter stringFromDate:date_radar]);
+
+  // Test 7 : correct
+  [formatter setDateFormat:@"yyyy_QQ_MM_WW_dd_EE"];
+  NSLog(@"yyyy_QQ_MM_WW_dd_EE %@", [formatter stringFromDate:date_radar]);
+
+  // Test 8 : correct
+  [formatter setDateFormat:@"yyyy_QQ_MM_WW_dd_ee"];
+  NSLog(@"yyyy_QQ_MM_WW_dd_ee %@", [formatter stringFromDate:date_radar]);
+
+  // Test 9 : correct
+  [formatter setDateFormat:@"yyyy_QQ_MM_WW_DD_EE"];
+  NSLog(@"yyyy_QQ_MM_WW_DD_EE %@", [formatter stringFromDate:date_radar]);
+
+  // Test 10 : correct
+  [formatter setDateFormat:@"yyyy_QQ_MM_WW_DD_ee"];
+  NSLog(@"yyyy_QQ_MM_WW_DD_ee %@", [formatter stringFromDate:date_radar]);
+
+  // Test 11 : correct
+  [formatter setDateFormat:@"yyyy_QQ_MM_WW_F_EE"];
+  NSLog(@"yyyy_QQ_MM_WW_F_EE %@", [formatter stringFromDate:date_radar]);
+
+  // Test 12 : correct
+  [formatter setDateFormat:@"yyyy_QQ_MM_WW_F_ee"];
+  NSLog(@"yyyy_QQ_MM_WW_F_ee %@", [formatter stringFromDate:date_radar]);
+
+  // Test 13 : incorrect
+  [formatter setDateFormat:@"YYYY_QQ_MM_ww_dd_EE"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-2]]:28: warning: use of week year (Y) with quarter number (Q); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_QQ_MM_ww_dd_EE %@", [formatter stringFromDate:date_radar]);
+
+  // Test 14 : incorrect
+  [formatter setDateFormat:@"YYYY_QQ_MM_ww_dd_ee"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-2]]:28: warning: use of week year (Y) with quarter number (Q); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_QQ_MM_ww_dd_ee %@", [formatter stringFromDate:date_radar]);
+
+  // Test 15 : incorrect
+  [formatter setDateFormat:@"YYYY_QQ_MM_ww_DD_EE"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with day of the year (D); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-2]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-3]]:28: warning: use of week year (Y) with quarter number (Q); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_QQ_MM_ww_DD_EE %@", [formatter stringFromDate:date_radar]);
+
+  // Test 16 : incorrect
+  [formatter setDateFormat:@"YYYY_QQ_MM_ww_DD_ee"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with day of the year (D); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-2]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-3]]:28: warning: use of week year (Y) with quarter number (Q); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_QQ_MM_ww_DD_ee %@", [formatter stringFromDate:date_radar]);
+
+  // Test 17 : incorrect
+  [formatter setDateFormat:@"YYYY_QQ_MM_ww_F_EE"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with day of the week in month (F); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-2]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-3]]:28: warning: use of week year (Y) with quarter number (Q); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_QQ_MM_ww_F_EE %@", [formatter stringFromDate:date_radar]);
+
+  // Test 18 : incorrect
+  [formatter setDateFormat:@"YYYY_QQ_MM_ww_F_ee"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with day of the week in month (F); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-2]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-3]]:28: warning: use of week year (Y) with quarter number (Q); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_QQ_MM_ww_F_ee %@", [formatter stringFromDate:date_radar]);
+
+  // Test 19 : incorrect
+  [formatter setDateFormat:@"YYYY_QQ_MM_WW_dd_EE"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-2]]:28: warning: use of week year (Y) with quarter number (Q); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-3]]:28: warning: use of week year (Y) with week of the month (W); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_QQ_MM_WW_dd_EE %@", [formatter stringFromDate:date_radar]);
+
+  // Test 20 : incorrect
+  [formatter setDateFormat:@"YYYY_QQ_MM_WW_dd_ee"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-2]]:28: warning: use of week year (Y) with quarter number (Q); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-3]]:28: warning: use of week year (Y) with week of the month (W); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_QQ_MM_WW_dd_ee %@", [formatter stringFromDate:date_radar]);
+
+  // Test 21 : incorrect
+  [formatter setDateFormat:@"YYYY_QQ_MM_WW_DD_EE"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with day of the year (D); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-2]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-3]]:28: warning: use of week year (Y) with quarter number (Q); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-4]]:28: warning: use of week year (Y) with week of the month (W); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_QQ_MM_WW_DD_EE %@", [formatter stringFromDate:date_radar]);
+
+  // Test 22 : incorrect
+  [formatter setDateFormat:@"YYYY_QQ_MM_WW_DD_ee"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with day of the year (D); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-2]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-3]]:28: warning: use of week year (Y) with quarter number (Q); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-4]]:28: warning: use of week year (Y) with week of the month (W); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_QQ_MM_WW_DD_ee %@", [formatter stringFromDate:date_radar]);
+
+  // Test 23 : incorrect
+  [formatter setDateFormat:@"YYYY_QQ_MM_WW_F_EE"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with day of the week in month (F); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-2]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-3]]:28: warning: use of week year (Y) with quarter number (Q); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-4]]:28: warning: use of week year (Y) with week of the month (W); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_QQ_MM_WW_F_EE %@", [formatter stringFromDate:date_radar]);
+
+  // Test 24 : incorrect
+  [formatter setDateFormat:@"YYYY_QQ_MM_WW_F_ee"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: use of week year (Y) with day of the week in month (F); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-2]]:28: warning: use of week year (Y) with month (M); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-3]]:28: warning: use of week year (Y) with quarter number (Q); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  // CHECK-MESSAGES: :[[@LINE-4]]:28: warning: use of week year (Y) with week of the month (W); did you mean to use calendar year (y) instead? [objc-nsdate-formatter]
+  NSLog(@"YYYY_QQ_MM_WW_F_ee %@", [formatter stringFromDate:date_radar]);
+}
+
++ (void)testMethod3 {
+  NSDateFormatter *Formatter = [[NSDateFormatter alloc] init];
+  NSDateComponents *Comps = [[NSDateComponents alloc] init];
+  [Comps setDay:29];
+  [Comps setMonth:12];
+  [Comps setYear:2014];
+  NSDate *DateRadar = [[NSCalendar currentCalendar] dateFromComponents:Comps];
+
+  // Incorrect : has reserved and invalid chars
+  [Formatter setDateFormat:@"Rashmi"];
+  // CHECK-MESSAGES: :[[@LINE-1]]:28: warning: invalid date format specifier [objc-nsdate-formatter]
+  NSLog(@"Rashmi %@", [Formatter stringFromDate:DateRadar]);
+
+  // Correct
+  [Formatter setDateFormat:@"AMy"];
+  NSLog(@"AMy %@", [Formatter stringFromDate:DateRadar]);
+}
+
++ (void)testAnotherClass {
+    AnotherClass *Formatter = [[AnotherClass alloc] init];
+    [Formatter setDateFormat:@"RandomString"];
+    [Formatter setDateFormat:@"YYYY_QQ_MM_WW_dd_EE"];
+}
+@end