Fix another case where loop-convert wasn't handling correctly data members.

[angelgarcia]

Summary

If the container expression was obtained from the point where "size" (which usually is a const method) is invoked, then the topmost node in this expression may be an implicit cast to const.

When the container is a data member, the check was trying to obtain the member expression directly and was failing in the case mentioned above. This is solved by ignoring implicit casts.

[angelgarcia]

Update the method comment.

[klimek]

lg

clang-tidy/modernize/LoopConvertCheck.cpp

if (SourceMgr.getFileID(Range.getBegin()) !=
       SourceMgr.getFileID(Range.getEnd())) {
     return StringRef(); // Empty string.
   }
 
   return Lexer::getSourceText(CharSourceRange(Range, true), SourceMgr,
                               LangOpts);
 }
 
-/// \brief If the given expression is actually a DeclRefExpr, find and return
-/// the underlying ValueDecl; otherwise, return NULL.
+/// \brief If the given expression is actually a DeclRefExpr or a MemberExpr,
+/// find and return the underlying ValueDecl; otherwise, return NULL.
 static const ValueDecl *getReferencedVariable(const Expr *E) {
   if (const DeclRefExpr *DRE = getDeclRef(E))
     return dyn_cast<VarDecl>(DRE->getDecl());
-  if (const auto *Mem = dyn_cast<MemberExpr>(E))
+  if (const auto *Mem = dyn_cast<MemberExpr>(E->IgnoreParenImpCasts()))
     return dyn_cast<FieldDecl>(Mem->getMemberDecl());
   return nullptr;
 }
 
 /// \brief Returns true when the given expression is a member expression
 /// whose base is `this` (implicitly or not).
 static bool isDirectMemberExpr(const Expr *E) {
   if (const auto *Member = dyn_cast<MemberExpr>(E->IgnoreParenImpCasts()))

test/clang-tidy/modernize-loop-convert-extra.cpp

void refs_and_vals() {
   for (int I = 0, E = Dep.size(); I != E; ++I) {
     int Idx = Other.at(I);
   }
 }
 
 struct MemberNaming {
   const static int N = 10;
   int Ints[N], Ints_[N];
+  dependent<int> DInts;
   void loops() {
     for (int I = 0; I < N; ++I) {
       printf("%d\n", Ints[I]);
     }
     // CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use range-based for loop instead
     // CHECK-FIXES: for (int Int : Ints)
     // CHECK-FIXES-NEXT: printf("%d\n", Int);
 
     for (int I = 0; I < N; ++I) {
       printf("%d\n", Ints_[I]);
     }
     // CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use range-based for loop instead
     // CHECK-FIXES: for (int Int : Ints_)
     // CHECK-FIXES-NEXT: printf("%d\n", Int);
+
+    for (int I = 0; I < DInts.size(); ++I) {
+      printf("%d\n", DInts[I]);
+    }
+    // CHECK-MESSAGES: :[[@LINE-3]]:5: warning: use range-based for loop instead
+    // CHECK-FIXES: for (int DInt : DInts)
+    // CHECK-FIXES-NEXT: printf("%d\n", DInt);
   }
+
+  void outOfLine();
 };
+void MemberNaming::outOfLine() {
+  for (int I = 0; I < N; ++I) {
+    printf("%d\n", Ints[I]);
+  }
+  // CHECK-MESSAGES: :[[@LINE-3]]:3: warning: use range-based for loop instead
+  // CHECK-FIXES: for (int Int : Ints)
+  // CHECK-FIXES-NEXT: printf("%d\n", Int);
+
+  for (int I = 0; I < N; ++I) {
+    printf("%d\n", Ints_[I]);
+  }
+  // CHECK-MESSAGES: :[[@LINE-3]]:3: warning: use range-based for loop instead
+  // CHECK-FIXES: for (int Int : Ints_)
+  // CHECK-FIXES-NEXT: printf("%d\n", Int);
+}
 
 } // namespace NamingAlias
 
 namespace NamingConlict {
 
 #define MAX(a, b) (a > b) ? a : b
 #define DEF 5