[clang-tidy] Give readability-redundant-string-init a customizable list of string types to fix

Summary:
This patch adds a feature requested in https://reviews.llvm.org/D69238 to enable `readability-redundant-string-init` to take a list of strings to apply the fix to rather than hard-coding `basic_string`. It adds a `StringNames` option of semicolon-delimited names of string classes to which to apply this fix. Tests ensure this works with test class out::TestString as well as std::string and std::wstring as before. It should be applicable to llvm::StringRef, QString, etc.

Reviewers: MyDeveloperDay, aaron.ballman, hokein, alexfh, JonasToth, gribozavr2

Patch by: poelmanc

Subscribers: gribozavr2, xazax.hun, Eugene.Zelenko, cfe-commits

Tags: #clang-tools-extra, #clang

Differential Revision: https://reviews.llvm.org/D69548

1 files changed, 14 insertions, 1 deletions

diff --git a/clang-tools-extra/docs/clang-tidy/checks/readability-redundant-string-init.rst b/clang-tools-extra/docs/clang-tidy/checks/readability-redundant-string-init.rst
index e4136ea4234..c4556887f89 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/readability-redundant-string-init.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/readability-redundant-string-init.rst
@@ -5,7 +5,8 @@ readability-redundant-string-init
 
 Finds unnecessary string initializations.
 
-Examples:
+Examples
+--------
 
 .. code-block:: c++
 
@@ -17,3 +18,15 @@ Examples:
 
   std::string a;
   std::string b;
+
+Options
+-------
+
+.. option:: StringNames
+
+    Default is `::std::basic_string`.
+
+    Semicolon-delimited list of class names to apply this check to.
+    By default `::std::basic_string` applies to ``std::string`` and
+    ``std::wstring``. Set to e.g. `::std::basic_string;llvm::StringRef;QString`
+    to perform this check on custom classes.