[clang-tidy] Fix an assertion failure in `modernize-use-nullptr` check.

[alexfh]

Looks good! Thank you for coming up with the reduced test.

[hokein]

Correct test code format.

clang-tools-extra/trunk/clang-tidy/modernize/UseNullptrCheck.cpp

while (true) {
           return false;
 
         StringRef Name =
             Lexer::getImmediateMacroName(OldArgLoc, SM, Context.getLangOpts());
         return std::find(NullMacros.begin(), NullMacros.end(), Name) !=
                NullMacros.end();
       }
 
-      MacroLoc = SM.getImmediateExpansionRange(ArgLoc).first;
+      MacroLoc = SM.getExpansionRange(ArgLoc).first;
 
       ArgLoc = Expansion.getSpellingLoc().getLocWithOffset(LocInfo.second);
       if (ArgLoc.isFileID())
         return true;
 
       // If spelling location resides in the same FileID as macro expansion
       // location, it means there is no inner macro.
       FileID MacroFID = SM.getFileID(MacroLoc);

clang-tools-extra/trunk/test/clang-tidy/modernize-use-nullptr.cpp

 #define ENTRY(X) {X}
   struct A {
     int *Ptr;
   } a[2] = {ENTRY(0), {0}};
   // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: use nullptr
   // CHECK-MESSAGES: :[[@LINE-2]]:24: warning: use nullptr
   // CHECK-FIXES: a[2] = {ENTRY(nullptr), {nullptr}};
 #undef ENTRY
+
+#define assert1(expr) (expr) ? 0 : 1
+#define assert2 assert1
+  int *p;
+  assert2(p == 0);
+  // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use nullptr
+  // CHECK-FIXES: assert2(p == nullptr);
+  assert2(p == NULL);
+  // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: use nullptr
+  // CHECK-FIXES: assert2(p == nullptr);
+#undef assert2
+#undef assert1
 }
 
 // One of the ancestor of the cast is a NestedNameSpecifierLoc.
 class NoDef;
 char function(NoDef *p);
 #define F(x) (sizeof(function(x)) == 1)
 template<class T, T t>
 class C {};
 C<bool, F(0)> c;
 // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: use nullptr
 // CHECK-FIXES: C<bool, F(nullptr)> c;
 #undef F