From 9916cf22ac559501eeb360f98b47333948013667 Mon Sep 17 00:00:00 2001
From: John Bytheway <jbytheway@gmail.com>
Date: Mon, 4 May 2020 20:49:51 -0400
Subject: [PATCH] Expand localized sorting to cover pair, tuple

Warn about comparison or sorting of pairs or tuples where one of the
elements is a string.
---
 .../UseLocalizedSortingCheck.cpp              | 48 +++++++++++++++++--
 .../test/use-localized-sorting.cpp            | 41 ++++++++++++++++
 2 files changed, 85 insertions(+), 4 deletions(-)

diff --git a/tools/clang-tidy-plugin/UseLocalizedSortingCheck.cpp b/tools/clang-tidy-plugin/UseLocalizedSortingCheck.cpp
index e72a15d672cbc..1bdaff7b534d8 100644
--- a/tools/clang-tidy-plugin/UseLocalizedSortingCheck.cpp
+++ b/tools/clang-tidy-plugin/UseLocalizedSortingCheck.cpp
@@ -33,14 +33,54 @@ namespace tidy
 namespace cata
 {
 
-inline bool IsString( QualType T )
+static bool IsStringish( QualType T );
+
+static bool IsStringish( const TemplateArgument &Arg )
+{
+    switch( Arg.getKind() ) {
+        case TemplateArgument::Type:
+            if( IsStringish( Arg.getAsType() ) ) {
+                return true;
+            }
+            break;
+        case TemplateArgument::Pack:
+            for( const TemplateArgument &PackArg : Arg.getPackAsArray() ) {
+                if( IsStringish( PackArg ) ) {
+                    return true;
+                }
+            }
+            break;
+        default:
+            break;
+    }
+    return false;
+}
+
+static bool IsStringish( QualType T )
 {
     const TagDecl *TTag = T.getTypePtr()->getAsTagDecl();
     if( !TTag ) {
         return false;
     }
     StringRef Name = TTag->getName();
-    return Name == "basic_string";
+    if( Name == "basic_string" ) {
+        return true;
+    }
+    if( Name == "pair" || Name == "tuple" ) {
+        const ClassTemplateSpecializationDecl *SpecDecl =
+            dyn_cast<ClassTemplateSpecializationDecl>( TTag );
+        if( !SpecDecl ) {
+            fprintf( stderr, "Not a spec: %s\n", TTag->getKindName().str().c_str() );
+            return false;
+        }
+        const TemplateArgumentList &Args = SpecDecl->getTemplateArgs();
+        for( const TemplateArgument &Arg : Args.asArray() ) {
+            if( IsStringish( Arg ) ) {
+                return true;
+            }
+        }
+    }
+    return false;
 }
 
 void UseLocalizedSortingCheck::registerMatchers( MatchFinder *Finder )
@@ -81,7 +121,7 @@ static void CheckOpCall( UseLocalizedSortingCheck &Check, const MatchFinder::Mat
         return;
     }
 
-    if( !IsString( *Arg0Type ) ) {
+    if( !IsStringish( *Arg0Type ) ) {
         return;
     }
 
@@ -123,7 +163,7 @@ static void CheckSortCall( UseLocalizedSortingCheck &Check, const MatchFinder::M
         ValueType = *BoundValueType;
     }
 
-    if( !IsString( ValueType ) ) {
+    if( !IsStringish( ValueType ) ) {
         return;
     }
 
diff --git a/tools/clang-tidy-plugin/test/use-localized-sorting.cpp b/tools/clang-tidy-plugin/test/use-localized-sorting.cpp
index 1ecea6e77c218..5914548437b96 100644
--- a/tools/clang-tidy-plugin/test/use-localized-sorting.cpp
+++ b/tools/clang-tidy-plugin/test/use-localized-sorting.cpp
@@ -24,6 +24,18 @@ bool operator<( const std::basic_string<CharT, Traits, Alloc> &lhs,
 template<class RandomIt>
 void sort( RandomIt first, RandomIt last );
 
+template<class T1, class T2>
+struct pair;
+
+template< class T1, class T2 >
+bool operator<( const std::pair<T1, T2> &lhs, const std::pair<T1, T2> &rhs );
+
+template< class... Types >
+class tuple;
+
+template<class... TTypes, class... UTypes>
+bool operator<( const tuple<TTypes...> &lhs,
+                const tuple<UTypes...> &rhs );
 }
 
 template<class T>
@@ -48,6 +60,35 @@ bool f1( const NonString &l, const NonString &r )
     return l < r;
 }
 
+bool f2( const std::pair<int, std::string> &l, const std::pair<int, std::string> &r )
+{
+    return l < r;
+    // CHECK-MESSAGES: warning: Raw comparison of 'const std::pair<int, std::string>' (aka 'const pair<int, basic_string<char> >'). For UI purposes please use localized_compare from translations.h. [cata-use-localized-sorting]
+}
+
+bool f3( const std::pair<int, NonString> &l, const std::pair<int, NonString> &r )
+{
+    return l < r;
+}
+
+bool f4( const std::tuple<int, std::string> &l, const std::tuple<int, std::string> &r )
+{
+    return l < r;
+    // CHECK-MESSAGES: warning: Raw comparison of 'const std::tuple<int, std::string>' (aka 'const tuple<int, basic_string<char> >').  For UI purposes please use localized_compare from translations.h. [cata-use-localized-sorting]
+}
+
+bool f5( const std::tuple<int, NonString> &l, const std::tuple<int, NonString> &r )
+{
+    return l < r;
+}
+
+bool f4( const std::tuple<std::tuple<std::string>> &l,
+         const std::tuple<std::tuple<std::string>> &r )
+{
+    return l < r;
+    // CHECK-MESSAGES: warning: Raw comparison of 'const std::tuple<std::tuple<std::string> >' (aka 'const tuple<tuple<basic_string<char> > >'). For UI purposes please use localized_compare from translations.h. [cata-use-localized-sorting]
+}
+
 bool sort0( const std::string *start, const std::string *end )
 {
     std::sort( start, end );