Prevent modernize-use-auto from emitting a warning when 'auto' was already being used.

[angelgarcia]

Summary

This fixes https://llvm.org/bugs/show_bug.cgi?id=25082 .

[alexfh]

test/clang-tidy/modernize-use-auto-new.cpp

100

Please add tests for auto * and const auto *.

[angelgarcia]

Good point. Solved.

[angelgarcia]

Ping

[klimek]

lg

clang-tidy/modernize/UseAutoCheck.cpp

return declStmt(
       .bind(IteratorDeclStmtId);
 }
 
 StatementMatcher makeDeclWithNewMatcher() {
   return declStmt(
              has(varDecl()),
              unless(has(varDecl(anyOf(
                  unless(hasInitializer(ignoringParenImpCasts(cxxNewExpr()))),
+                 // Skip declarations that are already using auto.
+                 anyOf(hasType(autoType()),
+                       hasType(pointerType(pointee(autoType())))),
                  // FIXME: TypeLoc information is not reliable where CV
                  // qualifiers are concerned so these types can't be
                  // handled for now.
                  hasType(pointerType(
                      pointee(hasCanonicalType(hasLocalQualifiers())))),
 
                  // FIXME: Handle function pointers. For now we ignore them
                  // because the replacement replaces the entire type

test/clang-tidy/modernize-use-auto-new.cpp

MyType *ptr2{new MyType};
 
     // Different types should not be transformed.
     int_p e = new int, *f = new int_p;
 
     int_p *g = new int*, *h = new int_p;
     // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: use auto when initializing with new
     // CHECK-FIXES: auto g = new int*, h = new int_p;
   }
+
+  // Don't warn when 'auto' is already being used.
+  auto aut = new MyType();
+  auto *paut = new MyType();
+  const auto *pcaut = new MyType();
 }