[clang-tidy] Don't generate fixes for invalid new expr location in modernize-make-unique.

[ilya-biryukov]

Should we fix the endloc bug instead? Or is that too hard?

[hokein]

In D42363#983641, @ilya-biryukov wrote:

Should we fix the endloc bug instead? Or is that too hard?

Yeah, we should fix the clang bug (root cause). But I think this patch still makes sense -- as we usually ignore invalid cases in clang-tidy checks.

[ilya-biryukov]

In D42363#983769, @hokein wrote:

Yeah, we should fix the clang bug (root cause). But I think this patch still makes sense -- as we usually ignore invalid cases in clang-tidy checks.

Sure, thanks for clarifying. LGTM.
It's a bit unfortunate that the test will break when we fix an actual bug in clang. But it's just something to watch out for, still nice to have a test after the bug is fixed.

clang-tidy/modernize/MakeSmartPtrCheck.cpp

 }
 
 bool MakeSmartPtrCheck::replaceNew(DiagnosticBuilder &Diag,
                                    const CXXNewExpr *New,
                                    SourceManager& SM) {
   SourceLocation NewStart = New->getSourceRange().getBegin();
   SourceLocation NewEnd = New->getSourceRange().getEnd();
 
+  // Skip when the source location of the new expression is invalid.
+  if (NewStart.isInvalid() || NewEnd.isInvalid())
+    return false;
+
   std::string ArraySizeExpr;
   if (const auto* ArraySize = New->getArraySize()) {
     ArraySizeExpr = Lexer::getSourceText(CharSourceRange::getTokenRange(
                                              ArraySize->getSourceRange()),
                                          SM, getLangOpts())
                         .str();
   }
 

test/clang-tidy/modernize-make-unique.cpp

void template_fun(T* t) {
   std::unique_ptr<T> t2 = std::unique_ptr<T>(new T);
   t2.reset(new T);
 }
 
 void invoke_template() {
   Foo* foo;
   template_fun(foo);
 }
+
+void no_fix_for_invalid_new_loc() {
+  // FIXME: Although the code is valid, the end location of `new struct Base` is
+  // invalid. Correct it once https://bugs.llvm.org/show_bug.cgi?id=35952 is
+  // fixed.
+  auto T = std::unique_ptr<Base>(new struct Base);
+  // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: use std::make_unique instead
+  // CHECK-FIXES: auto T = std::unique_ptr<Base>(new struct Base);
+}