From 3e576dd19465b264e9f93e71d0ffe19c7b782130 Mon Sep 17 00:00:00 2001
From: Lucian Popescu <lucian.popescu@tecnico.ulisboa.pt>
Date: Sat, 19 Sep 2026 22:07:54 +0100
Subject: [PATCH] Translate variable template declarations

---
 cpp2rust/converter/converter.cpp     |  7 +++++++
 cpp2rust/converter/converter.h       |  1 +
 cpp2rust/converter/converter_lib.cpp |  4 ++++
 tests/unit/out/refcount/templates.rs | 16 +++++++++++++++-
 tests/unit/out/unsafe/templates.rs   | 14 +++++++++++++-
 tests/unit/templates.cpp             |  7 +++++++
 6 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/cpp2rust/converter/converter.cpp b/cpp2rust/converter/converter.cpp
index cf33029e6..8d27b141b 100644
--- a/cpp2rust/converter/converter.cpp
+++ b/cpp2rust/converter/converter.cpp
@@ -490,6 +490,13 @@ bool Converter::VisitFunctionTemplateDecl(clang::FunctionTemplateDecl *decl) {
   return false;
 }
 
+bool Converter::VisitVarTemplateDecl(clang::VarTemplateDecl *decl) {
+  for (auto *var_decl : decl->specializations()) {
+    VisitVarDecl(var_decl);
+  }
+  return false;
+}
+
 void Converter::ConvertVaListVarDecl(clang::VarDecl *decl) {
   if (clang::isa<clang::ParmVarDecl>(decl)) {
     // va_list parameter (decayed to __va_list_tag *)
diff --git a/cpp2rust/converter/converter.h b/cpp2rust/converter/converter.h
index 9387ee749..b87feedaa 100644
--- a/cpp2rust/converter/converter.h
+++ b/cpp2rust/converter/converter.h
@@ -98,6 +98,7 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {
   void EmitHoistedDecls(clang::CompoundStmt *body);
 
   virtual bool VisitFunctionTemplateDecl(clang::FunctionTemplateDecl *decl);
+  bool VisitVarTemplateDecl(clang::VarTemplateDecl *decl);
 
   virtual bool VisitVarDecl(clang::VarDecl *decl);
   virtual bool LazyStaticInit() const { return true; }
diff --git a/cpp2rust/converter/converter_lib.cpp b/cpp2rust/converter/converter_lib.cpp
index 0dbb2fd11..08d572d8d 100644
--- a/cpp2rust/converter/converter_lib.cpp
+++ b/cpp2rust/converter/converter_lib.cpp
@@ -574,6 +574,10 @@ static std::string GetParamSignature(const clang::Decl *decl) {
 
 static std::string GetLexicalSpecializationID(const clang::Decl *decl) {
   std::string id;
+  if (const auto *var =
+          clang::dyn_cast<clang::VarTemplateSpecializationDecl>(decl)) {
+    id += clang::ASTNameGenerator(var->getASTContext()).getName(var);
+  }
   if (const auto *spec =
           clang::dyn_cast<clang::ClassTemplateSpecializationDecl>(
               decl->getLexicalDeclContext());
diff --git a/tests/unit/out/refcount/templates.rs b/tests/unit/out/refcount/templates.rs
index 8c662110d..bda085f1d 100644
--- a/tests/unit/out/refcount/templates.rs
+++ b/tests/unit/out/refcount/templates.rs
@@ -44,6 +44,12 @@ pub fn func_5(x1: f64, x2: i32, x3: f64) -> i32 {
     let x3: Value<f64> = Rc::new(RefCell::new(x3));
     return ((((*x1.borrow()) + ((*x2.borrow()) as f64)) + (*x3.borrow())) as i32);
 }
+thread_local!(
+    pub static half_6: Value<i32> = Rc::new(RefCell::new((1 / 2)));
+);
+thread_local!(
+    pub static half_7: Value<f64> = Rc::new(RefCell::new((1_f64 / 2_f64)));
+);
 pub fn main() {
     __cpp2rust_init_globals();
     std::process::exit(main_0());
@@ -59,6 +65,14 @@ fn main_0() -> i32 {
             + (({ func_5(2.0E+0, (*x.borrow()), (*y.borrow()),) }) as f64))
             == 68_f64)
     );
+    assert!((half_6.with(|rc| rc.borrow().clone()) == 0));
+    assert!((half_7.with(|rc| rc.borrow().clone()) == 5.0E-1));
+    (*half_6.with(Value::clone).borrow_mut()) = 7;
+    assert!((half_6.with(|rc| rc.borrow().clone()) == 7));
+    assert!((half_7.with(|rc| rc.borrow().clone()) == 5.0E-1));
     return 0;
 }
-pub fn __cpp2rust_init_globals() {}
+pub fn __cpp2rust_init_globals() {
+    let _ = half_6.with(|_| ());
+    let _ = half_7.with(|_| ());
+}
diff --git a/tests/unit/out/unsafe/templates.rs b/tests/unit/out/unsafe/templates.rs
index f9300b546..267a70314 100644
--- a/tests/unit/out/unsafe/templates.rs
+++ b/tests/unit/out/unsafe/templates.rs
@@ -24,6 +24,10 @@ pub unsafe fn func_4(mut x1: i32, mut x2: i32, mut x3: i32) -> i32 {
 pub unsafe fn func_5(mut x1: f64, mut x2: i32, mut x3: f64) -> i32 {
     return ((((x1) + (x2 as f64)) + (x3)) as i32);
 }
+pub static mut half_6: std::cell::LazyCell<i32> =
+    std::cell::LazyCell::new(|| unsafe { ((1) / (2)) });
+pub static mut half_7: std::cell::LazyCell<f64> =
+    std::cell::LazyCell::new(|| unsafe { ((1_f64) / (2_f64)) });
 pub fn main() {
     unsafe {
         __cpp2rust_init_globals();
@@ -41,6 +45,14 @@ unsafe fn main_0() -> i32 {
             + ((unsafe { func_5(2.0E+0, x, y,) }) as f64))
             == (68_f64))
     );
+    assert!(((*std::cell::LazyCell::force_mut(&mut *&raw mut half_6)) == (0)));
+    assert!(((*std::cell::LazyCell::force_mut(&mut *&raw mut half_7)) == (5.0E-1)));
+    (*std::cell::LazyCell::force_mut(&mut *&raw mut half_6)) = 7;
+    assert!(((*std::cell::LazyCell::force_mut(&mut *&raw mut half_6)) == (7)));
+    assert!(((*std::cell::LazyCell::force_mut(&mut *&raw mut half_7)) == (5.0E-1)));
     return 0;
 }
-pub unsafe fn __cpp2rust_init_globals() {}
+pub unsafe fn __cpp2rust_init_globals() {
+    std::cell::LazyCell::force(&*&raw const half_6);
+    std::cell::LazyCell::force(&*&raw const half_7);
+}
diff --git a/tests/unit/templates.cpp b/tests/unit/templates.cpp
index c0af5c3c6..e7b238154 100644
--- a/tests/unit/templates.cpp
+++ b/tests/unit/templates.cpp
@@ -8,11 +8,18 @@ template <typename T1, typename T2, typename T3> int func(T1 x1, T2 x2, T3 x3) {
   return x1 + x2 + x3;
 }
 
+template <typename T> T half = T(1) / T(2);
+
 int main() {
   int x = 10;
   double y = x;
   assert(foo(x) + foo(y) + *bar(&x, true) + *bar(&y, true) + func(1, 2, 3) +
              func(2.0, x, y) ==
          68);
+  assert(half<int> == 0);
+  assert(half<double> == 0.5);
+  half<int> = 7;
+  assert(half<int> == 7);
+  assert(half<double> == 0.5);
   return 0;
 }