nunoplopes · Oct 8, 2026 · Oct 7, 2026 · Oct 7, 2026
diff --git a/cpp2rust/converter/converter.h b/cpp2rust/converter/converter.h
@@ -503,6 +503,10 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {
     return true;
   }
 
+  bool TraverseExplicitInstantiationDecl(clang::ExplicitInstantiationDecl *) {
+    return true;
+  }
+
   virtual bool
   VisitCXXStdInitializerListExpr(clang::CXXStdInitializerListExpr *expr);
 

diff --git a/cpp2rust/converter/converter_lib.cpp b/cpp2rust/converter/converter_lib.cpp
@@ -265,7 +265,15 @@ bool IsCodeUnitStringLiteral(const clang::StringLiteral *expr) {
 bool IsUserDefinedDecl(const clang::Decl *decl) {
   const auto &ctx = decl->getASTContext();
   const auto &src_mgr = ctx.getSourceManager();
-  const auto src_loc = decl->getLocation();
+  auto src_loc = decl->getLocation();
+  if (auto *spec =
+          clang::dyn_cast<clang::ClassTemplateSpecializationDecl>(decl);
+      spec && (spec->getSpecializationKind() ==
+                   clang::TSK_ExplicitInstantiationDeclaration ||
+               spec->getSpecializationKind() ==
+                   clang::TSK_ExplicitInstantiationDefinition)) {
+    src_loc = spec->getSpecializedTemplate()->getLocation();
+  }
   return !decl->getBeginLoc().isInvalid() && !decl->isImplicit() &&
          !src_mgr.isInSystemHeader(src_loc) &&
          !src_mgr.isInSystemMacro(src_loc);

diff --git a/tests/unit/class_templates.cpp b/tests/unit/class_templates.cpp
@@ -39,7 +39,20 @@ template <typename T> struct Outer {
   Inner<int> with(int n) const { return Inner<int>{v, n}; }
 };
 
+struct Elem {
+  int i;
+};
+
+template class std::vector<Elem>;
+
+template struct Boxed<short>;
+
 int main() {
+  std::vector<Elem> ev;
+  ev.push_back(Elem{2});
+  assert(ev[0].i == 2);
+  assert(Boxed<short>::twice(2) == 4);
+
   Outer<int> oi{3};
   assert(oi.with(4).sum() == 7);
   Outer<long> ol{5};

diff --git a/tests/unit/out/refcount/class_templates.rs b/tests/unit/out/refcount/class_templates.rs
@@ -28,6 +28,17 @@ pub struct MyContainer_float_ {
     vec_: Value<Vec<f32>>,
 }
 #[derive(Clone, Record, ByteRepr, VaArg, FnPtrArg, Default)]
+#[byte_size(2)]
+pub struct Boxed_short_ {
+    #[offset(0)]
+    pub value: i16,
+}
+impl Boxed_short_ {
+    pub fn twice(mut v: i16) -> i16 {
+        return (((v as i32) + (v as i32)) as i16);
+    }
+}
+#[derive(Clone, Record, ByteRepr, VaArg, FnPtrArg, Default)]
 #[byte_size(4)]
 pub struct Boxed_int_ {
     #[offset(0)]
@@ -85,11 +96,24 @@ pub struct Outer_long_ {
     #[offset(0)]
     pub v: i64,
 }
+#[derive(Clone, Record, ByteRepr, VaArg, FnPtrArg, Default)]
+#[byte_size(4)]
+pub struct Elem {
+    #[offset(0)]
+    pub i: i32,
+}
 pub fn main() {
     __cpp2rust_init_globals();
     std::process::exit(main_0());
 }
 fn main_0() -> i32 {
+    let mut ev: Vec<Elem> = Vec::new();
+    {
+        let __a1 = Elem { i: 2 };
+        ev.push(__a1)
+    };
+    assert!(({ ev[0_usize].i } == 2));
+    assert!(((({ Boxed_short_::twice(2_i16,) }) as i32) == 4));
     let oi: Value<Outer_int_> = Rc::new(RefCell::new(Outer_int_ { v: 3 }));
     assert!(
         (({
@@ -181,6 +205,14 @@ impl Boxed_long_Impl for Ptr<Boxed_long_> {
         return ((*self).with(|__s| __s.value) + other);
     }
 }
+pub trait Boxed_short_Impl {
+    fn plus(&self, other: i16) -> i16;
+}
+impl Boxed_short_Impl for Ptr<Boxed_short_> {
+    fn plus(&self, mut other: i16) -> i16 {
+        return ((((*self).with(|__s| __s.value) as i32) + (other as i32)) as i16);
+    }
+}
 pub trait MyContainer_char_Impl {
     fn empty(&self) -> bool;
     fn size(&self) -> usize;

diff --git a/tests/unit/out/unsafe/class_templates.rs b/tests/unit/out/unsafe/class_templates.rs
@@ -86,6 +86,19 @@ impl MyContainer_float_ {
 }
 #[repr(C)]
 #[derive(Copy, Clone, VaArg, FnPtrArg, Default)]
+pub struct Boxed_short_ {
+    pub value: i16,
+}
+impl Boxed_short_ {
+    pub unsafe fn twice(mut v: i16) -> i16 {
+        return (((v as i32) + (v as i32)) as i16);
+    }
+    pub unsafe fn plus(&self, mut other: i16) -> i16 {
+        return (((self.value as i32) + (other as i32)) as i16);
+    }
+}
+#[repr(C)]
+#[derive(Copy, Clone, VaArg, FnPtrArg, Default)]
 pub struct Boxed_int_ {
     pub value: i32,
 }
@@ -163,13 +176,25 @@ impl Outer_long_ {
         return Outer_long__Inner_int_ { t: self.v, u: n };
     }
 }
+#[repr(C)]
+#[derive(Copy, Clone, VaArg, FnPtrArg, Default)]
+pub struct Elem {
+    pub i: i32,
+}
 pub fn main() {
     unsafe {
         __cpp2rust_init_globals();
         std::process::exit(main_0() as i32);
     }
 }
 unsafe fn main_0() -> i32 {
+    let mut ev: Vec<Elem> = Vec::new();
+    {
+        let __a1 = Elem { i: 2 };
+        ev.push(__a1)
+    };
+    assert!(((ev[(0_usize)].i) == (2)));
+    assert!((((unsafe { Boxed_short_::twice(2_i16,) }) as i32) == (4)));
     let mut oi: Outer_int_ = Outer_int_ { v: 3 };
     assert!(
         ((unsafe { Outer_int__Inner_int_::sum(&(unsafe { Outer_int_::with(&oi, 4,) }),) }) == (7))