Ignore direct init VarDecl and add some tests

Author: flovent

clang-tools-extra/clang-tidy/modernize/UseStructuredBindingCheck.cpp

@@ -184,6 +184,10 @@ AST_MATCHER(CXXRecordDecl, isPairType) {
   });
 }
 
+AST_MATCHER(VarDecl, isDirectInitialization) {
+  return Node.getInitStyle() != VarDecl::InitializationStyle::CInit;
+}
+
 } // namespace
 
 static auto getVarInitWithMemberMatcher(
@@ -267,7 +271,7 @@ void UseStructuredBindingCheck::registerMatchers(MatchFinder *Finder) {
       declStmt(
           unless(isInMarco()),
           hasSingleDecl(
-              varDecl(UnlessShouldBeIgnored,
+              varDecl(UnlessShouldBeIgnored, unless(isDirectInitialization()),
                       hasType(qualType(anyOf(PairType, lValueReferenceType(
                                                            pointee(PairType))))
                                   .bind(PairVarTypeName)),

clang-tools-extra/test/clang-tidy/checkers/modernize/Inputs/use-structured-binding/fake_std_pair_tuple.h

@@ -3,6 +3,9 @@ namespace std {
   struct pair {
     T1 first;
     T2 second;
+
+    pair() = default;
+    pair(T1 first, T2 second) : first(first), second(second) {}
   };
 
   template<typename... Args>

clang-tools-extra/test/clang-tidy/checkers/modernize/use-structured-binding.cpp

@@ -600,3 +600,23 @@ void StaticFieldPairTests() {
     int y = P.second;
   }
 }
+
+void IgnoreDirectInit() {
+  {
+    std::pair<int, int> P{1, 1};
+    int x = P.first;
+    int y = P.second; 
+  }
+
+  {
+    std::pair<int, int> P(1, 1);
+    int x = P.first;
+    int y = P.second;
+  }
+
+  {
+    std::pair<int, int> P;
+    int x = P.first;
+    int y = P.second;
+  }
+}