[PATCH] D133006: [clang-tidy] Skip copy assignment operators with nonstandard return types

[Alexander Shaposhnikov via Phabricator via cfe-commits]

alexander-shaposhnikov created this revision.
alexander-shaposhnikov added reviewers: njames93, gribozavr2, aaron.ballman.
alexander-shaposhnikov created this object with visibility "All Users".
Herald added subscribers: carlosgalvezp, xazax.hun.
Herald added a project: All.
alexander-shaposhnikov requested review of this revision.
Herald added a project: clang-tools-extra.
Herald added a subscriber: cfe-commits.

Skip copy assignment operators with nonstandard return types since they cannot 
be defaulted.

Test plan: ninja check-clang-tools


Repository:
  rL LLVM

https://reviews.llvm.org/D133006

Files:
  clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
  clang-tools-extra/docs/ReleaseNotes.rst
  
clang-tools-extra/test/clang-tidy/checkers/modernize/use-equals-default-copy.cpp


Index: 
clang-tools-extra/test/clang-tidy/checkers/modernize/use-equals-default-copy.cpp
===================================================================
--- 
clang-tools-extra/test/clang-tidy/checkers/modernize/use-equals-default-copy.cpp
+++ 
clang-tools-extra/test/clang-tidy/checkers/modernize/use-equals-default-copy.cpp
@@ -444,6 +444,13 @@
   return *this;
 }
 
+// Wrong return type.
+struct WRTConstRef {
+  const WRTConstRef &operator = (const WRTConstRef &) {
+    return *this;
+  }
+};
+
 // Try-catch.
 struct ITC {
   ITC(const ITC &Other)
Index: clang-tools-extra/docs/ReleaseNotes.rst
===================================================================
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -139,7 +139,8 @@
 - Improved `modernize-use-equals-default 
<clang-tidy/checks/modernize/use-equals-default.html>`_ check.
 
   The check now skips unions since in this case a default constructor with 
empty body
-  is not equivalent to the explicitly defaulted one.
+  is not equivalent to the explicitly defaulted one. The check also skips
+  copy assignment operators with nonstandard return types.
 
 Removed checks
 ^^^^^^^^^^^^^^
Index: clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
+++ clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
@@ -8,6 +8,7 @@
 
 #include "UseEqualsDefaultCheck.h"
 #include "../utils/LexerUtils.h"
+#include "../utils/Matchers.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Lexer.h"
@@ -247,7 +248,12 @@
                     // isCopyAssignmentOperator() allows the parameter to be
                     // passed by value, and in this case it cannot be
                     // defaulted.
-                    hasParameter(0, hasType(lValueReferenceType())))
+                    hasParameter(0, hasType(lValueReferenceType())),
+                    // isCopyAssignmentOperator() allows non lvalue reference
+                    // return types, and in this case it cannot be defaulted.
+                    returns(qualType(hasCanonicalType(
+                        allOf(lValueReferenceType(pointee(type())),
+                              unless(matchers::isReferenceToConst()))))))
           .bind(SpecialFunction),
       this);
 }



Index: clang-tools-extra/test/clang-tidy/checkers/modernize/use-equals-default-copy.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/modernize/use-equals-default-copy.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/modernize/use-equals-default-copy.cpp
@@ -444,6 +444,13 @@
   return *this;
 }
 
+// Wrong return type.
+struct WRTConstRef {
+  const WRTConstRef &operator = (const WRTConstRef &) {
+    return *this;
+  }
+};
+
 // Try-catch.
 struct ITC {
   ITC(const ITC &Other)
Index: clang-tools-extra/docs/ReleaseNotes.rst
===================================================================
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -139,7 +139,8 @@
 - Improved `modernize-use-equals-default <clang-tidy/checks/modernize/use-equals-default.html>`_ check.
 
   The check now skips unions since in this case a default constructor with empty body
-  is not equivalent to the explicitly defaulted one.
+  is not equivalent to the explicitly defaulted one. The check also skips
+  copy assignment operators with nonstandard return types.
 
 Removed checks
 ^^^^^^^^^^^^^^
Index: clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
+++ clang-tools-extra/clang-tidy/modernize/UseEqualsDefaultCheck.cpp
@@ -8,6 +8,7 @@
 
 #include "UseEqualsDefaultCheck.h"
 #include "../utils/LexerUtils.h"
+#include "../utils/Matchers.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Lex/Lexer.h"
@@ -247,7 +248,12 @@
                     // isCopyAssignmentOperator() allows the parameter to be
                     // passed by value, and in this case it cannot be
                     // defaulted.
-                    hasParameter(0, hasType(lValueReferenceType())))
+                    hasParameter(0, hasType(lValueReferenceType())),
+                    // isCopyAssignmentOperator() allows non lvalue reference
+                    // return types, and in this case it cannot be defaulted.
+                    returns(qualType(hasCanonicalType(
+                        allOf(lValueReferenceType(pointee(type())),
+                              unless(matchers::isReferenceToConst()))))))
           .bind(SpecialFunction),
       this);
 }

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