From 5805c679437d39b6b8f9b14c628f7480607a484d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johel=20Ernesto=20Guerrero=20Pe=C3=B1a?=
 <johelegp@gmail.com>
Date: Tue, 1 Oct 2024 18:14:38 -0400
Subject: [PATCH] fix(to_cpp1): emit template template parameters

---
 ...ugfix-for-template-template-parameter.cpp2 |  5 +++
 ...bugfix-for-template-template-parameter.cpp | 32 +++++++++++++++++
 ...or-template-template-parameter.cpp2.output |  2 ++
 source/parse.h                                |  2 ++
 source/to_cpp1.h                              | 34 +++++++++++++------
 5 files changed, 65 insertions(+), 10 deletions(-)
 create mode 100644 regression-tests/pure2-bugfix-for-template-template-parameter.cpp2
 create mode 100644 regression-tests/test-results/pure2-bugfix-for-template-template-parameter.cpp
 create mode 100644 regression-tests/test-results/pure2-bugfix-for-template-template-parameter.cpp2.output

diff --git a/regression-tests/pure2-bugfix-for-template-template-parameter.cpp2 b/regression-tests/pure2-bugfix-for-template-template-parameter.cpp2
new file mode 100644
index 000000000..a3c48a174
--- /dev/null
+++ b/regression-tests/pure2-bugfix-for-template-template-parameter.cpp2
@@ -0,0 +1,5 @@
+t: @struct <T: <_, _: _>> type = { }
+
+u: @struct <T, V: _> type = { }
+
+main: () = { _ = :t<u> = (); }
diff --git a/regression-tests/test-results/pure2-bugfix-for-template-template-parameter.cpp b/regression-tests/test-results/pure2-bugfix-for-template-template-parameter.cpp
new file mode 100644
index 000000000..fde9ec26c
--- /dev/null
+++ b/regression-tests/test-results/pure2-bugfix-for-template-template-parameter.cpp
@@ -0,0 +1,32 @@
+
+#define CPP2_IMPORT_STD          Yes
+
+//=== Cpp2 type declarations ====================================================
+
+
+#include "cpp2util.h"
+
+#line 1 "pure2-bugfix-for-template-template-parameter.cpp2"
+template<template <typename UnnamedTypeParam1_1, auto UnnamedTypeParam2_2> class T> class t;
+#line 2 "pure2-bugfix-for-template-template-parameter.cpp2"
+
+template<typename T, auto V> class u;
+
+
+//=== Cpp2 type definitions and function declarations ===========================
+
+#line 1 "pure2-bugfix-for-template-template-parameter.cpp2"
+template<template <typename UnnamedTypeParam1_1, auto UnnamedTypeParam2_2> class T> class t {};
+#line 2 "pure2-bugfix-for-template-template-parameter.cpp2"
+
+template<typename T, auto V> class u {};
+
+auto main() -> int;
+
+//=== Cpp2 function definitions =================================================
+
+#line 1 "pure2-bugfix-for-template-template-parameter.cpp2"
+
+#line 5 "pure2-bugfix-for-template-template-parameter.cpp2"
+auto main() -> int{static_cast<void>(t<u>{}); }
+
diff --git a/regression-tests/test-results/pure2-bugfix-for-template-template-parameter.cpp2.output b/regression-tests/test-results/pure2-bugfix-for-template-template-parameter.cpp2.output
new file mode 100644
index 000000000..d7b69b444
--- /dev/null
+++ b/regression-tests/test-results/pure2-bugfix-for-template-template-parameter.cpp2.output
@@ -0,0 +1,2 @@
+pure2-bugfix-for-template-template-parameter.cpp2... ok (all Cpp2, passes safety checks)
+
diff --git a/source/parse.h b/source/parse.h
index a8ad4bd9e..debb2e37d 100644
--- a/source/parse.h
+++ b/source/parse.h
@@ -3347,6 +3347,8 @@ struct declaration_node
 
     auto is_function_expression () const -> bool
         { return is_function() && !identifier;  }
+    auto is_template() const -> bool
+        { return template_parameters != nullptr; }
 
     auto is_polymorphic() const // has base types or virtual functions
         -> bool
diff --git a/source/to_cpp1.h b/source/to_cpp1.h
index 4a891ad1d..3dd1740b0 100644
--- a/source/to_cpp1.h
+++ b/source/to_cpp1.h
@@ -1255,7 +1255,7 @@ class cppfront
 
         //  Now we'll open the Cpp1 file
         auto cpp1_filename = sourcefile.substr(0, std::ssize(sourcefile) - 1);
-        
+
         //  Use explicit filename override if present,
         //  otherwise strip leading path
         if (!flag_cpp1_filename.empty()) {
@@ -3458,12 +3458,12 @@ class cppfront
                 last_was_prefixed = true;
             }
 
-            //  Handle the other Cpp2 postfix operators that stay postfix in Cpp1 
+            //  Handle the other Cpp2 postfix operators that stay postfix in Cpp1
             //  (currently '...' for expansion, not when used as a range operator)
             else if (
                 is_postfix_operator(i->op->type())
                 && !i->last_expr    // not being used as a range operator
-                ) 
+                )
             {
                 flush_args();
                 suffix.emplace_back( i->op->to_string(), i->op->position());
@@ -3504,7 +3504,7 @@ class cppfront
                     }
 
                     auto print = print_to_string(
-                        *i->id_expr, 
+                        *i->id_expr,
                         false, // not a local name
                         i->op->type() == lexeme::Dot || i->op->type() == lexeme::DotDot // member access
                     );
@@ -4453,8 +4453,8 @@ class cppfront
         {
             assert(n.declaration);
             auto is_param_to_namespace_scope_type =
-                n.declaration->parent_is_type() 
-                && n.declaration->parent_declaration->parent_is_namespace() 
+                n.declaration->parent_is_type()
+                && n.declaration->parent_declaration->parent_is_namespace()
                 ;
 
             auto emit_in_phase_0 =
@@ -4584,6 +4584,20 @@ class cppfront
             return;
         }
 
+        //-----------------------------------------------------------------------
+        //  Handle template parameters
+
+        if (n.declaration->is_template()) {
+            assert( n.declaration->is_template() );
+            printer.print_cpp2("template ", identifier_pos);
+            emit(*n.declaration->template_parameters, is_returns, true);
+            printer.print_cpp2(" class ", identifier_pos);
+
+            emit_template_name();
+            emit_initializer();
+            return;
+        }
+
         //-----------------------------------------------------------------------
         //  Else handle template non-type parameters
 
@@ -5091,7 +5105,7 @@ class cppfront
             || n.is_swap()
             || n.is_destructor()
             || (
-                n.my_decl 
+                n.my_decl
                 && generating_move_from == n.my_decl
                 )
             )
@@ -5105,7 +5119,7 @@ class cppfront
         if (
             n.is_assignment()
             || (
-                n.my_decl 
+                n.my_decl
                 && generating_assignment_from == n.my_decl
                 )
             )
@@ -6995,8 +7009,8 @@ class cppfront
                         return;
                     }
                 }
-                printer.preempt_position_push(n.position()); 
-                emit( *type, {}, print_to_string(*n.identifier) ); 
+                printer.preempt_position_push(n.position());
+                emit( *type, {}, print_to_string(*n.identifier) );
                 printer.preempt_position_pop();
 
                 if (