From 97610ec59bbb8e4a0db74a713113fae77121c091 Mon Sep 17 00:00:00 2001
From: Dimitar Dobrev <dpldobrev@protonmail.com>
Date: Fri, 29 Oct 2021 21:46:43 +0300
Subject: [PATCH] Rename templates only used through aliases

Signed-off-by: Dimitar Dobrev <dpldobrev@protonmail.com>
---
 src/Generator/Passes/StripUnusedSystemTypesPass.cs | 14 +++++++++++---
 src/Generator/Passes/TrimSpecializationsPass.cs    |  2 +-
 tests/NamespacesDerived/NamespacesDerived.Tests.cs |  2 ++
 tests/NamespacesDerived/NamespacesDerived.h        |  5 ++++-
 4 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/src/Generator/Passes/StripUnusedSystemTypesPass.cs b/src/Generator/Passes/StripUnusedSystemTypesPass.cs
index 9422f43832..4d111cb7fb 100644
--- a/src/Generator/Passes/StripUnusedSystemTypesPass.cs
+++ b/src/Generator/Passes/StripUnusedSystemTypesPass.cs
@@ -59,8 +59,16 @@ private bool TryMarkType(Type desugared)
             var templateType = desugared as TemplateSpecializationType;
             if (templateType != null)
             {
-                MarkAsUsed(templateType.Template);
-                MarkAsUsed(templateType.Template.TemplatedDecl);
+                var template = templateType.Template;
+                if (template.TemplatedDecl is TypeAlias typeAlias &&
+                    typeAlias.Type.Desugar() is TemplateSpecializationType specializationType)
+                {
+                    MarkAsUsed(template);
+                    MarkAsUsed(template.TemplatedDecl);
+                    template = specializationType.Template;
+                }
+                MarkAsUsed(template);
+                MarkAsUsed(template.TemplatedDecl);
                 return true;
             }
 
@@ -90,6 +98,6 @@ private void RemoveUnusedStdTypes(DeclarationContext context)
             }
         }
 
-        private HashSet<Declaration> usedStdTypes = new HashSet<Declaration>();
+        private readonly HashSet<Declaration> usedStdTypes = new HashSet<Declaration>();
     }
 }
diff --git a/src/Generator/Passes/TrimSpecializationsPass.cs b/src/Generator/Passes/TrimSpecializationsPass.cs
index 3c0df01920..22f718392d 100644
--- a/src/Generator/Passes/TrimSpecializationsPass.cs
+++ b/src/Generator/Passes/TrimSpecializationsPass.cs
@@ -158,7 +158,7 @@ private static void TryMoveExternalSpecializations(Class template)
                                let module = arg.Type.Type.GetModule()
                                where module != null
                                select module).ToList().TopologicalSort(m => m.Dependencies);
-                if (modules.Any())
+                if (modules.Count > 0)
                 {
                     var module = modules.Last();
                     module.ExternalClassTemplateSpecializations.Add(specialization);
diff --git a/tests/NamespacesDerived/NamespacesDerived.Tests.cs b/tests/NamespacesDerived/NamespacesDerived.Tests.cs
index b2a3d4c8de..f6dfe0973d 100644
--- a/tests/NamespacesDerived/NamespacesDerived.Tests.cs
+++ b/tests/NamespacesDerived/NamespacesDerived.Tests.cs
@@ -15,6 +15,8 @@ public void TestCodeGeneration()
         using (new DerivedFromSecondaryBaseInDependency()) { }
         using (var der2 = new Derived2())
         using (der2.LocalTypedefSpecialization) { }
+        Std.Vector.__Internalc__N_std_S_vector__i___S_CustomAllocator__i i;
+        i.GetHashCode();
     }
 
     [Test]
diff --git a/tests/NamespacesDerived/NamespacesDerived.h b/tests/NamespacesDerived/NamespacesDerived.h
index 5d14ebe2bb..9615a0e989 100644
--- a/tests/NamespacesDerived/NamespacesDerived.h
+++ b/tests/NamespacesDerived/NamespacesDerived.h
@@ -109,10 +109,13 @@ class DLL_API Ignored
     std::basic_string<char, std::char_traits<char>, CustomAllocator<char>> customAllocatedString;
 };
 
+template<class T, class Alloc = CustomAllocator<T>>
+using vector = ::std::vector<T, Alloc>;
+
 class DLL_API StdFields
 {
 private:
-    std::vector<unsigned int, CustomAllocator<unsigned int>> customAllocatedVector;
+   vector<unsigned int, CustomAllocator<unsigned int>> customAllocatedVector;
 };
 
 DLL_API bool operator<<(const Base& b, const char* str);