From b99630e432614d06b380afb15c466665065eaa0a Mon Sep 17 00:00:00 2001
From: Nathan James <n.james93@hotmail.co.uk>
Date: Wed, 29 Jul 2020 15:35:28 +0100
Subject: [PATCH] [clang-tidy] Fix RedundantStringCStrCheck with r values

The previous fix for this, https://reviews.llvm.org/D76761, Passed test cases but failed in the real world as std::string has a non trivial destructor so creates a CXXBindTemporaryExpr.

This handles that shortfall and updates the test case std::basic_string implementation to use a non trivial destructor to reflect real world behaviour.

Reviewed By: gribozavr2

Differential Revision: https://reviews.llvm.org/D84831
---
 .../readability/RedundantStringCStrCheck.cpp       | 14 ++++++++------
 .../checkers/readability-redundant-string-cstr.cpp |  2 ++
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/readability/RedundantStringCStrCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantStringCStrCheck.cpp
index bea02a6ba111b..1f371eed2db80 100644
--- a/clang-tools-extra/clang-tidy/readability/RedundantStringCStrCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/RedundantStringCStrCheck.cpp
@@ -92,16 +92,18 @@ void RedundantStringCStrCheck::registerMatchers(
                         callee(memberExpr().bind("member")),
                         callee(cxxMethodDecl(hasAnyName("c_str", "data"))))
           .bind("call");
-
+  const auto HasRValueTempParent =
+      hasParent(materializeTemporaryExpr(unless(isBoundToLValue())));
   // Detect redundant 'c_str()' calls through a string constructor.
   // If CxxConstructExpr is the part of some CallExpr we need to
   // check that matched ParamDecl of the ancestor CallExpr is not rvalue.
   Finder->addMatcher(
-      traverse(ast_type_traits::TK_AsIs,
-               cxxConstructExpr(StringConstructorExpr,
-                                hasArgument(0, StringCStrCallExpr),
-                                unless(hasParent(materializeTemporaryExpr(
-                                    unless(isBoundToLValue())))))),
+      traverse(
+          ast_type_traits::TK_AsIs,
+          cxxConstructExpr(
+              StringConstructorExpr, hasArgument(0, StringCStrCallExpr),
+              unless(anyOf(HasRValueTempParent, hasParent(cxxBindTemporaryExpr(
+                                                    HasRValueTempParent)))))),
       this);
 
   // Detect: 's == str.c_str()'  ->  's == str'
diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability-redundant-string-cstr.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability-redundant-string-cstr.cpp
index 2561b81805bda..e1df8cccc10b3 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/readability-redundant-string-cstr.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/readability-redundant-string-cstr.cpp
@@ -15,6 +15,8 @@ struct basic_string {
   basic_string();
   basic_string(const C *p, const A &a = A());
 
+  ~basic_string();
+
   const C *c_str() const;
   const C *data() const;