[clang-tidy] Fix handling of members in readability-redundant-member-init (#93217)

Compare class type instead of just assuming
that called constructor belong to same class.

Fixes #91605

clang-tools-extra/clang-tidy/readability/RedundantMemberInitCheck.cpp

@@ -41,25 +41,35 @@ void RedundantMemberInitCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
 
 void RedundantMemberInitCheck::registerMatchers(MatchFinder *Finder) {
   auto ConstructorMatcher =
-      cxxConstructExpr(argumentCountIs(0),
-                       hasDeclaration(cxxConstructorDecl(ofClass(cxxRecordDecl(
-                           unless(isTriviallyDefaultConstructible()))))))
+      cxxConstructExpr(
+          argumentCountIs(0),
+          hasDeclaration(cxxConstructorDecl(
+              ofClass(cxxRecordDecl(unless(isTriviallyDefaultConstructible()))
+                          .bind("class")))))
           .bind("construct");
 
+  auto HasUnionAsParent = hasParent(recordDecl(isUnion()));
+
+  auto HasTypeEqualToConstructorClass = hasType(qualType(
+      hasCanonicalType(qualType(hasDeclaration(equalsBoundNode("class"))))));
+
   Finder->addMatcher(
       cxxConstructorDecl(
           unless(isDelegatingConstructor()), ofClass(unless(isUnion())),
           forEachConstructorInitializer(
-              cxxCtorInitializer(withInitializer(ConstructorMatcher),
-                                 unless(forField(fieldDecl(
-                                     anyOf(hasType(isConstQualified()),
-                                           hasParent(recordDecl(isUnion())))))))
+              cxxCtorInitializer(
+                  withInitializer(ConstructorMatcher),
+                  anyOf(isBaseInitializer(),
+                        forField(fieldDecl(unless(hasType(isConstQualified())),
+                                           unless(HasUnionAsParent),
+                                           HasTypeEqualToConstructorClass))))
                   .bind("init")))
           .bind("constructor"),
       this);
 
   Finder->addMatcher(fieldDecl(hasInClassInitializer(ConstructorMatcher),
-                               unless(hasParent(recordDecl(isUnion()))))
+                               HasTypeEqualToConstructorClass,
+                               unless(HasUnionAsParent))
                          .bind("field"),
                      this);
 }

clang-tools-extra/docs/ReleaseNotes.rst

@@ -403,6 +403,11 @@ Changes in existing checks
   <clang-tidy/checks/readability/redundant-inline-specifier>` check to properly
   emit warnings for static data member with an in-class initializer.
 
+- Improved :doc:`readability-redundant-member-init
+  <clang-tidy/checks/readability/redundant-member-init>` check to avoid
+  false-positives when type of the member does not match the type of the
+  initializer.
+
 - Improved :doc:`readability-static-accessed-through-instance
   <clang-tidy/checks/readability/static-accessed-through-instance>` check to
   support calls to overloaded operators as base expression and provide fixes to

clang-tools-extra/test/clang-tidy/checkers/readability/redundant-member-init.cpp

@@ -302,3 +302,19 @@ struct D7 {
 
 D7<int> d7i;
 D7<S> d7s;
+
+struct SS {
+  SS() = default;
+  SS(S s) : s(s) {}
+
+  S s;
+};
+
+struct D8 {
+  SS ss = S();
+};
+
+struct D9 {
+  D9() : ss(S()) {}
+  SS ss;
+};