From 96355da34edf51cc813400115984050bd7c50630 Mon Sep 17 00:00:00 2001
From: Phil Nash <github@philnash.me>
Date: Tue, 21 May 2019 00:04:19 +0100
Subject: [PATCH] StringRef no longer repoints m_start to m_data after c_str()
 on a substring.

This fixes an issue where a self-assignment of a StringRef copy would point into internally (and now dangling) data.
(now self-assignment check is no longer needed)
---
 include/internal/catch_stringref.cpp                  | 9 +++++----
 include/internal/catch_stringref.h                    | 4 ++--
 projects/SelfTest/IntrospectiveTests/String.tests.cpp | 8 +++-----
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/include/internal/catch_stringref.cpp b/include/internal/catch_stringref.cpp
index 9e9095e4..90a320c9 100644
--- a/include/internal/catch_stringref.cpp
+++ b/include/internal/catch_stringref.cpp
@@ -39,9 +39,11 @@ namespace Catch {
     }
 
     auto StringRef::c_str() const -> char const* {
-        if( isSubstring() )
-           const_cast<StringRef*>( this )->takeOwnership();
-        return m_start;
+        if( !isSubstring() )
+            return m_start;
+
+        const_cast<StringRef *>( this )->takeOwnership();
+        return m_data;
     }
     auto StringRef::currentData() const noexcept -> char const* {
         return m_start;
@@ -59,7 +61,6 @@ namespace Catch {
             m_data = new char[m_size+1];
             memcpy( m_data, m_start, m_size );
             m_data[m_size] = '\0';
-            m_start = m_data;
         }
     }
     auto StringRef::substr( size_type start, size_type size ) const noexcept -> StringRef {
diff --git a/include/internal/catch_stringref.h b/include/internal/catch_stringref.h
index 4e41bd47..70f68476 100644
--- a/include/internal/catch_stringref.h
+++ b/include/internal/catch_stringref.h
@@ -71,12 +71,12 @@ namespace Catch {
         }
 
         auto operator = ( StringRef const &other ) noexcept -> StringRef& {
-            if( this != &other ) {
+//            if( this != &other ) {
                 delete[] m_data;
                 m_data = nullptr;
                 m_start = other.m_start;
                 m_size = other.m_size;
-            }
+  //          }
             return *this;
         }
 
diff --git a/projects/SelfTest/IntrospectiveTests/String.tests.cpp b/projects/SelfTest/IntrospectiveTests/String.tests.cpp
index 8bf2ffb3..876d4a09 100644
--- a/projects/SelfTest/IntrospectiveTests/String.tests.cpp
+++ b/projects/SelfTest/IntrospectiveTests/String.tests.cpp
@@ -65,7 +65,6 @@ TEST_CASE( "StringRef", "[Strings][StringRef]" ) {
 
         original.c_str(); // Forces it to take ownership
 
-        REQUIRE( isSubstring( original ) == false );
         REQUIRE( isOwned( original ) );
     }
 
@@ -88,14 +87,13 @@ TEST_CASE( "StringRef", "[Strings][StringRef]" ) {
             REQUIRE( rawChars == s.currentData() ); // same pointer value
             REQUIRE( ss.c_str() != rawChars );
 
-            REQUIRE( isSubstring( ss ) == false );
             REQUIRE( isOwned( ss ) );
 
-            REQUIRE( ss.currentData() != s.currentData() ); // different pointer value
-
             SECTION( "Self-assignment after substring" ) {
                 ss = *&ss; // the *& are there to suppress warnings (see: "Improvements to Clang's diagnostics" in https://rev.ng/gitlab/revng-bar-2019/clang/raw/master/docs/ReleaseNotes.rst)
-                REQUIRE(isOwned(ss) == true);
+                REQUIRE( isOwned(ss) == false );
+                REQUIRE( ss == "hello" );
+                REQUIRE( rawChars == ss.currentData() ); // same pointer value
             }
         }