Avoid converting |char* field| to |CheckedPtr<char> field|.

The avoided conversion breaks compilation of string-literal based global
initialization like the example below:

    struct MyStruct {
      int foo;
      CheckedPtr<const char> bar;
    }
    MyStruct g_foo = {
        123,
        // Invokes CheckedPtr<char>'s constructor:
        "string literal"
    };

Bug: 1069567
Change-Id: I897a1fad9222b904ea6f70fd23bc508d253ff97d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2161146
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#768930}

tools/clang/rewrite_raw_ptr_fields/RewriteRawPtrFields.cpp

@@ -83,6 +83,10 @@ AST_MATCHER(clang::ClassTemplateSpecializationDecl, isImplicitSpecialization) {
   return !Node.isExplicitSpecialization();
 }
 
+AST_MATCHER(clang::Type, anyCharType) {
+  return Node.isAnyCharacterType();
+}
+
 class FieldDeclRewriter : public MatchFinder::MatchCallback {
  public:
   explicit FieldDeclRewriter(ReplacementsPrinter* replacements_printer)
@@ -179,8 +183,9 @@ int main(int argc, const char* argv[]) {
   // Supported pointer types =========
   // Given
   //   struct MyStrict {
-  //     int* ptr;
+  //     int* int_ptr;
   //     int i;
+  //     char* char_ptr;
   //     int (*func_ptr)();
   //     int (MyStruct::* member_func_ptr)(char);
   //     StructOrClassWithDeletedOperatorNew* stack_or_gc_ptr;
@@ -191,9 +196,9 @@ int main(int argc, const char* argv[]) {
   auto record_with_deleted_allocation_operator_type_matcher =
       recordType(hasDeclaration(cxxRecordDecl(
           hasMethod(allOf(hasOverloadedOperatorName("new"), isDeleted())))));
-  auto supported_pointer_types_matcher = pointerType(unless(
-      pointee(anyOf(function_pointer_type_matcher,
-                    record_with_deleted_allocation_operator_type_matcher))));
+  auto supported_pointer_types_matcher = pointerType(unless(pointee(anyOf(
+      function_pointer_type_matcher,
+      record_with_deleted_allocation_operator_type_matcher, anyCharType()))));
 
   // Implicit field declarations =========
   // Matches field declarations that do not explicitly appear in the source

tools/clang/rewrite_raw_ptr_fields/tests/various-types-expected.cc

@@ -100,6 +100,21 @@ struct MyStruct {
   typedef SomeClass* SomeClassPtrTypedef;
   // No rewrite expected (for now - in V1 we only rewrite field decls).
   using SomeClassPtrAlias = SomeClass*;
+
+  // Chromium is built with a warning/error that there are no user-defined
+  // constructors invoked when initializing global-scoped values.
+  // CheckedPtr<char> conversion might trigger a global constructor for string
+  // literals:
+  //     struct MyStruct {
+  //       int foo;
+  //       CheckedPtr<const char> bar;
+  //     }
+  //     MyStruct g_foo = {123, "string literal" /* global constr! */};
+  // Because of the above, no rewrite is expected below.
+  char* char_ptr;
+  const char* const_char_ptr;
+  wchar_t* wide_char_ptr;
+  const wchar_t* const_wide_char_ptr;
 };
 
 }  // namespace my_namespace

tools/clang/rewrite_raw_ptr_fields/tests/various-types-original.cc

@@ -98,6 +98,21 @@ struct MyStruct {
   typedef SomeClass* SomeClassPtrTypedef;
   // No rewrite expected (for now - in V1 we only rewrite field decls).
   using SomeClassPtrAlias = SomeClass*;
+
+  // Chromium is built with a warning/error that there are no user-defined
+  // constructors invoked when initializing global-scoped values.
+  // CheckedPtr<char> conversion might trigger a global constructor for string
+  // literals:
+  //     struct MyStruct {
+  //       int foo;
+  //       CheckedPtr<const char> bar;
+  //     }
+  //     MyStruct g_foo = {123, "string literal" /* global constr! */};
+  // Because of the above, no rewrite is expected below.
+  char* char_ptr;
+  const char* const_char_ptr;
+  wchar_t* wide_char_ptr;
+  const wchar_t* const_wide_char_ptr;
 };
 
 }  // namespace my_namespace