[clang-tidy/checks] Update objc-property-declaration check to allow arbitrary acronyms and initialisms 🔧

Summary:
§1 Description

This changes the objc-property-declaration check to allow arbitrary acronyms and initialisms instead of using whitelisted acronyms. In Objective-C it is relatively common to use project prefixes in property names for the purposes of disambiguation. For example, the CIColor¹ and CGColor² properties on UIColor both represent symbol prefixes being used in proeprty names outside of Apple's accepted acronyms³. The union of Apple's accepted acronyms and all symbol prefixes that might be used for disambiguation in property declarations effectively allows for any arbitrary sequence of capital alphanumeric characters to be acceptable in property declarations. This change updates the check accordingly.

The test variants with custom configurations are deleted as part of this change because their configurations no longer impact behavior. The acronym configurations are currently preserved for backwards compatibility of check configuration.

[1] https://developer.apple.com/documentation/uikit/uicolor/1621951-cicolor?language=objc
[2] https://developer.apple.com/documentation/uikit/uicolor/1621954-cgcolor?language=objc
[3] https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/CodingGuidelines/Articles/APIAbbreviations.html#//apple_ref/doc/uid/20001285-BCIHCGAE

§2 Test Notes

Changes verified by:
• Running clang-tidy unit tests.
• Used check_clang_tidy.py to verify expected output of processing objc-property-declaration.m

Reviewers: benhamilton, Wizard

Reviewed By: benhamilton

Subscribers: jfb, cfe-commits

Differential Revision: https://reviews.llvm.org/D51832

6 files changed, 29 insertions, 179 deletions

diff --git a/clang-tools-extra/clang-tidy/objc/PropertyDeclarationCheck.cpp b/clang-tools-extra/clang-tidy/objc/PropertyDeclarationCheck.cpp
index b772a5e6a0a..94b82f00f6a 100644
--- a/clang-tools-extra/clang-tidy/objc/PropertyDeclarationCheck.cpp
+++ b/clang-tools-extra/clang-tidy/objc/PropertyDeclarationCheck.cpp
@@ -29,104 +29,12 @@ namespace {
 // For CategoryProperty especially in categories of system class,
 // to avoid naming conflict, the suggested naming style is
 // 'abc_lowerCamelCase' (adding lowercase prefix followed by '_').
+// Regardless of the style, all acronyms and initialisms should be capitalized.
 enum NamingStyle {
   StandardProperty = 1,
   CategoryProperty = 2,
 };
 
-/// The acronyms are aggregated from multiple sources including
-/// https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/CodingGuidelines/Articles/APIAbbreviations.html#//apple_ref/doc/uid/20001285-BCIHCGAE
-///
-/// Keep this list sorted.
-constexpr llvm::StringLiteral DefaultSpecialAcronyms[] = {
-    "[2-9]G",
-    "ACL",
-    "API",
-    "APN",
-    "APNS",
-    "AR",
-    "ARGB",
-    "ASCII",
-    "AV",
-    "BGRA",
-    "CA",
-    "CDN",
-    "CF",
-    "CG",
-    "CI",
-    "CRC",
-    "CV",
-    "CMYK",
-    "DNS",
-    "FPS",
-    "FTP",
-    "GIF",
-    "GL",
-    "GPS",
-    "GUID",
-    "HD",
-    "HDR",
-    "HMAC",
-    "HTML",
-    "HTTP",
-    "HTTPS",
-    "HUD",
-    "ID",
-    "JPG",
-    "JS",
-    "JSON",
-    "LAN",
-    "LZW",
-    "LTR",
-    "MAC",
-    "MD",
-    "MDNS",
-    "MIDI",
-    "NS",
-    "OS",
-    "P2P",
-    "PDF",
-    "PIN",
-    "PNG",
-    "POI",
-    "PSTN",
-    "PTR",
-    "QA",
-    "QOS",
-    "RGB",
-    "RGBA",
-    "RGBX",
-    "RIPEMD",
-    "ROM",
-    "RPC",
-    "RTF",
-    "RTL",
-    "SC",
-    "SDK",
-    "SHA",
-    "SQL",
-    "SSO",
-    "TCP",
-    "TIFF",
-    "TOS",
-    "TTS",
-    "UI",
-    "URI",
-    "URL",
-    "UUID",
-    "VC",
-    "VO",
-    "VOIP",
-    "VPN",
-    "VR",
-    "W",
-    "WAN",
-    "X",
-    "XML",
-    "Y",
-    "Z",
-};
-
 /// For now we will only fix 'CamelCase' or 'abc_CamelCase' property to
 /// 'camelCase' or 'abc_camelCase'. For other cases the users need to
 /// come up with a proper name by their own.
@@ -150,26 +58,26 @@ FixItHint generateFixItHint(const ObjCPropertyDecl *Decl, NamingStyle Style) {
   return FixItHint();
 }
 
-std::string AcronymsGroupRegex(llvm::ArrayRef<std::string> EscapedAcronyms) {
-  return "(" +
-         llvm::join(EscapedAcronyms.begin(), EscapedAcronyms.end(), "s?|") +
-         "s?)";
-}
-
-std::string validPropertyNameRegex(llvm::ArrayRef<std::string> EscapedAcronyms,
-                                   bool UsedInMatcher) {
+std::string validPropertyNameRegex(bool UsedInMatcher) {
   // Allow any of these names:
   // foo
   // fooBar
   // url
   // urlString
+  // ID
+  // IDs
   // URL
   // URLString
   // bundleID
+  // CIColor
+  //
+  // Disallow names of this form:
+  // LongString
+  //
+  // aRbITRaRyCapS is allowed to avoid generating false positives for names
+  // like isVitaminBSupplement, CProgrammingLanguage, and isBeforeM.
   std::string StartMatcher = UsedInMatcher ? "::" : "^";
-  std::string AcronymsMatcher = AcronymsGroupRegex(EscapedAcronyms);
-  return StartMatcher + "(" + AcronymsMatcher + "[A-Z]?)?[a-z]+[a-z0-9]*(" +
-         AcronymsMatcher + "|([A-Z][a-z0-9]+)|A|I)*$";
+  return StartMatcher + "([a-z]|[A-Z][A-Z0-9])[a-z0-9A-Z]*$";
 }
 
 bool hasCategoryPropertyPrefix(llvm::StringRef PropertyName) {
@@ -177,8 +85,7 @@ bool hasCategoryPropertyPrefix(llvm::StringRef PropertyName) {
   return RegexExp.match(PropertyName);
 }
 
-bool prefixedPropertyNameValid(llvm::StringRef PropertyName,
-                               llvm::ArrayRef<std::string> Acronyms) {
+bool prefixedPropertyNameValid(llvm::StringRef PropertyName) {
   size_t Start = PropertyName.find_first_of('_');
   assert(Start != llvm::StringRef::npos && Start + 1 < PropertyName.size());
   auto Prefix = PropertyName.substr(0, Start);
@@ -186,7 +93,7 @@ bool prefixedPropertyNameValid(llvm::StringRef PropertyName,
     return false;
   }
   auto RegexExp =
-      llvm::Regex(llvm::StringRef(validPropertyNameRegex(Acronyms, false)));
+      llvm::Regex(llvm::StringRef(validPropertyNameRegex(false)));
   return RegexExp.match(PropertyName.substr(Start + 1));
 }
 }  // namespace
@@ -203,26 +110,11 @@ void PropertyDeclarationCheck::registerMatchers(MatchFinder *Finder) {
   // this check should only be applied to ObjC sources.
   if (!getLangOpts().ObjC) return;
 
-  if (IncludeDefaultAcronyms) {
-    EscapedAcronyms.reserve(llvm::array_lengthof(DefaultSpecialAcronyms) +
-                            SpecialAcronyms.size());
-    // No need to regex-escape the default acronyms.
-    EscapedAcronyms.insert(EscapedAcronyms.end(),
-                           std::begin(DefaultSpecialAcronyms),
-                           std::end(DefaultSpecialAcronyms));
-  } else {
-    EscapedAcronyms.reserve(SpecialAcronyms.size());
-  }
-  // In case someone defines a prefix which includes a regex
-  // special character, regex-escape all the user-defined prefixes.
-  std::transform(SpecialAcronyms.begin(), SpecialAcronyms.end(),
-                 std::back_inserter(EscapedAcronyms),
-                 [](const std::string &s) { return llvm::Regex::escape(s); });
   Finder->addMatcher(
       objcPropertyDecl(
           // the property name should be in Lower Camel Case like
           // 'lowerCamelCase'
-          unless(matchesName(validPropertyNameRegex(EscapedAcronyms, true))))
+          unless(matchesName(validPropertyNameRegex(true))))
           .bind("property"),
       this);
 }
@@ -234,14 +126,9 @@ void PropertyDeclarationCheck::check(const MatchFinder::MatchResult &Result) {
   auto *DeclContext = MatchedDecl->getDeclContext();
   auto *CategoryDecl = llvm::dyn_cast<ObjCCategoryDecl>(DeclContext);
 
-  auto SingleAcronymRegex =
-      llvm::Regex("^([a-zA-Z]+_)?" + AcronymsGroupRegex(EscapedAcronyms) + "$");
-  if (SingleAcronymRegex.match(MatchedDecl->getName())) {
-    return;
-  }
   if (CategoryDecl != nullptr &&
       hasCategoryPropertyPrefix(MatchedDecl->getName())) {
-    if (!prefixedPropertyNameValid(MatchedDecl->getName(), EscapedAcronyms) ||
+    if (!prefixedPropertyNameValid(MatchedDecl->getName()) ||
         CategoryDecl->IsClassExtension()) {
       NamingStyle Style = CategoryDecl->IsClassExtension() ? StandardProperty
                                                            : CategoryProperty;
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 19079686059..cec9645fe65 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -231,6 +231,10 @@ Improvements to clang-tidy
   - floating point - integer narrowing conversions,
   - constants with narrowing conversions (even in ternary operator).
 
+- The :doc:`objc-property-declaration
+  <clang-tidy/checks/objc-property-declaration>` check now ignores the
+  `Acronyms` and `IncludeDefaultAcronyms` options.
+
 Improvements to include-fixer
 -----------------------------
 
diff --git a/clang-tools-extra/docs/clang-tidy/checks/objc-property-declaration.rst b/clang-tools-extra/docs/clang-tidy/checks/objc-property-declaration.rst
index b372ccd1d0a..49df5102096 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/objc-property-declaration.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/objc-property-declaration.rst
@@ -47,23 +47,8 @@ Options
 
 .. option:: Acronyms
 
-   Semicolon-separated list of custom acronyms that can be used as a prefix
-   or a suffix of property names.
-
-   By default, appends to the list of default acronyms (
-   ``IncludeDefaultAcronyms`` set to ``1``).
-   If ``IncludeDefaultAcronyms`` is set to ``0``, instead replaces the
-   default list of acronyms.
+   This option is deprecated and ignored.
 
 .. option:: IncludeDefaultAcronyms
 
-   Integer value (defaults to ``1``) to control whether the default
-   acronyms are included in the list of acronyms.
-
-   If set to ``1``, the value in ``Acronyms`` is appended to the
-   default list of acronyms:
-
-   ``[2-9]G;ACL;API;APN;APNS;AR;ARGB;ASCII;AV;BGRA;CA;CDN;CF;CG;CI;CRC;CV;CMYK;DNS;FPS;FTP;GIF;GL;GPS;GUID;HD;HDR;HMAC;HTML;HTTP;HTTPS;HUD;ID;JPG;JS;JSON;LAN;LZW;LTR;MAC;MD;MDNS;MIDI;NS;OS;P2P;PDF;PIN;PNG;POI;PSTN;PTR;QA;QOS;RGB;RGBA;RGBX;RIPEMD;ROM;RPC;RTF;RTL;SC;SDK;SHA;SQL;SSO;TCP;TIFF;TOS;TTS;UI;URI;URL;UUID;VC;VO;VOIP;VPN;VR;W;WAN;X;XML;Y;Z``.
-
-   If set to ``0``, the value in ``Acronyms`` replaces the default list
-   of acronyms.
+   This option is deprecated and ignored.
diff --git a/clang-tools-extra/test/clang-tidy/objc-property-declaration-additional.m b/clang-tools-extra/test/clang-tidy/objc-property-declaration-additional.m
deleted file mode 100644
index bf836fa1869..00000000000
--- a/clang-tools-extra/test/clang-tidy/objc-property-declaration-additional.m
+++ /dev/null
@@ -1,15 +0,0 @@
-// RUN: %check_clang_tidy %s objc-property-declaration %t \
-// RUN: -config='{CheckOptions: \
-// RUN:  [{key: objc-property-declaration.Acronyms, value: "ABC;TGIF"}]}' \
-// RUN: --
-@class NSString;
-
-@interface Foo
-@property(assign, nonatomic) int AbcNotRealPrefix;
-// CHECK-MESSAGES: :[[@LINE-1]]:34: warning: property name 'AbcNotRealPrefix' not using lowerCamelCase style or not prefixed in a category, according to the Apple Coding Guidelines [objc-property-declaration]
-// CHECK-FIXES: @property(assign, nonatomic) int abcNotRealPrefix;
-@property(assign, nonatomic) int ABCCustomPrefix;
-@property(strong, nonatomic) NSString *ABC_custom_prefix;
-// CHECK-MESSAGES: :[[@LINE-1]]:40: warning: property name 'ABC_custom_prefix' not using lowerCamelCase style or not prefixed in a category, according to the Apple Coding Guidelines [objc-property-declaration]
-@property(assign, nonatomic) int GIFShouldIncludeStandardAcronym;
-@end
diff --git a/clang-tools-extra/test/clang-tidy/objc-property-declaration-custom.m b/clang-tools-extra/test/clang-tidy/objc-property-declaration-custom.m
deleted file mode 100644
index 68374ec0e8f..00000000000
--- a/clang-tools-extra/test/clang-tidy/objc-property-declaration-custom.m
+++ /dev/null
@@ -1,18 +0,0 @@
-// RUN: %check_clang_tidy %s objc-property-declaration %t \
-// RUN: -config='{CheckOptions: \
-// RUN:  [{key: objc-property-declaration.Acronyms, value: "ABC;TGIF"}, \
-// RUN:   {key: objc-property-declaration.IncludeDefaultAcronyms, value: 0}]}' \
-// RUN: --
-@class NSString;
-
-@interface Foo
-@property(assign, nonatomic) int AbcNotRealPrefix;
-// CHECK-MESSAGES: :[[@LINE-1]]:34: warning: property name 'AbcNotRealPrefix' not using lowerCamelCase style or not prefixed in a category, according to the Apple Coding Guidelines [objc-property-declaration]
-// CHECK-FIXES: @property(assign, nonatomic) int abcNotRealPrefix;
-@property(assign, nonatomic) int ABCCustomPrefix;
-@property(strong, nonatomic) NSString *ABC_custom_prefix;
-// CHECK-MESSAGES: :[[@LINE-1]]:40: warning: property name 'ABC_custom_prefix' not using lowerCamelCase style or not prefixed in a category, according to the Apple Coding Guidelines [objc-property-declaration]
-@property(assign, nonatomic) int GIFIgnoreStandardAcronym;
-// CHECK-MESSAGES: :[[@LINE-1]]:34: warning: property name 'GIFIgnoreStandardAcronym' not using lowerCamelCase style or not prefixed in a category, according to the Apple Coding Guidelines [objc-property-declaration]
-@property(strong, nonatomic) NSString *TGIF;
-@end
diff --git a/clang-tools-extra/test/clang-tidy/objc-property-declaration.m b/clang-tools-extra/test/clang-tidy/objc-property-declaration.m
index 26e2f9a5281..07a06205302 100644
--- a/clang-tools-extra/test/clang-tidy/objc-property-declaration.m
+++ b/clang-tools-extra/test/clang-tidy/objc-property-declaration.m
@@ -1,8 +1,12 @@
 // RUN: %check_clang_tidy %s objc-property-declaration %t
+@class CIColor;
+@class NSArray;
 @class NSData;
 @class NSString;
 @class UIViewController;
 
+typedef void *CGColorRef;
+
 @interface Foo
 @property(assign, nonatomic) int NotCamelCase;
 // CHECK-MESSAGES: :[[@LINE-1]]:34: warning: property name 'NotCamelCase' not using lowerCamelCase style or not prefixed in a category, according to the Apple Coding Guidelines [objc-property-declaration]
@@ -23,6 +27,9 @@
 @property(assign, nonatomic) int enableGLAcceleration;
 @property(assign, nonatomic) int ID;
 @property(assign, nonatomic) int hasADog;
+@property(nonatomic, readonly) CGColorRef CGColor;
+@property(nonatomic, readonly) CIColor *CIColor;
+@property(nonatomic, copy) NSArray *IDs;
 @end
 
 @interface Foo (Bar)