[PATCH] D26138: [clang-tidy] Add modernize-use-equals-delete check

Aaron Ballman via cfe-commits cfe-commits at lists.llvm.org
Mon Oct 31 14:15:52 PDT 2016

aaron.ballman added inline comments.

Comment at: clang-tidy/modernize/UseEqualsDeleteCheck.cpp:29
+            cxxMethodDecl(
+                anyOf(isCopyAssignmentOperator(), isMoveAssignmentOperator())),
+            cxxDestructorDecl()));
How about a conversion operator, like `operator bool()`? You'll sometimes see that one declared privately for similar reasons.

Comment at: clang-tidy/modernize/UseEqualsDeleteCheck.cpp:37
+                       // Ensure that all methods except private special member
+                       // functions are defined
+                       hasParent(cxxRecordDecl(hasMethod(unless(
Missing a full stop at the end of the comment.

Comment at: clang-tidy/modernize/UseEqualsDeleteCheck.cpp:46
+void UseEqualsDeleteCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *SpecialFunction =
+      Result.Nodes.getNodeAs<CXXMethodDecl>("SpecialFunction");
Should rename this to not hide the global `SpecialFunction` object, and use the global `SpecialFunction` object in place of the string literal here. Alternatively, leave this name alone and remove the global variable and just use the string literal; either is fine.

Comment at: clang-tidy/modernize/UseEqualsDeleteCheck.cpp:52
+  diag(SpecialFunction->getLocation(),
+       "use '= delete' to prevent a default special member function")
+      << FixItHint::CreateInsertion(EndLoc, " = delete");
This diagnostic isn't very clear to me -- what does it mean to "prevent" a default special member function?

The fixit for this is also somewhat unsatisfying as this takes a private, not-defined function and turns it into a private, deleted function. That's a very small win, because it only impacts code which could access the special member function in the first place (some compilers give a diagnostic about the special member function being inaccessible even if it's explicitly marked as deleted; clang is not one such compiler). Do we have a way to rewrite the access specifier for the special member function as well (kind of like how we have a way to handle includes we're adding)? I am guessing not yet, but if we do, that would be fantastic to use here.

Note, I don't think this should hold up your patch or the fixit. A small win is still a win. :-)

Comment at: test/clang-tidy/modernize-use-equals-delete.cpp:93
+  NegativeConstructNotImpl(const NegativeConstructNotImpl &);
Phab will not let me delete the unsubmitted comment I had about this, so I am leaving a junk comment instead. Your move, Phabricator.


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