fix: Emit defs/refs for using decls involving templates (#305)

Author: varungandhi-src

indexer/SymbolFormatter.cc

@@ -575,22 +575,34 @@ std::optional<std::string_view> SymbolFormatter::getUsingShadowSymbol(
         std::string_view disambiguator = "";
         // NOTE: First two branches can't be re-ordered as all
         // TemplateTypeParmDecls also TypeDecls
-        if (llvm::dyn_cast<clang::TemplateTypeParmDecl>(canonicalDecl)) {
-          suffix = scip::Descriptor::TypeParameter;
-        } else if (llvm::dyn_cast<clang::TypeDecl>(canonicalDecl)) {
-          suffix = scip::Descriptor::Type;
-        } else if (llvm::dyn_cast<clang::NamespaceDecl>(canonicalDecl)) {
-          suffix = scip::Descriptor::Namespace;
-        } else if (llvm::dyn_cast<clang::EnumConstantDecl>(canonicalDecl)
-                   || llvm::dyn_cast<clang::FieldDecl>(canonicalDecl)) {
-          suffix = scip::Descriptor::Term;
-        } else if (auto *functionDecl =
-                       llvm::dyn_cast<clang::FunctionDecl>(canonicalDecl)) {
-          disambiguator = this->getFunctionDisambiguator(*functionDecl, buf);
-          suffix = scip::Descriptor::Method;
-        } else {
-          return {};
-        }
+        // clang-format off
+        do {
+          if (llvm::dyn_cast<clang::TemplateTypeParmDecl>(canonicalDecl)) {
+            suffix = scip::Descriptor::TypeParameter;
+          } else if (llvm::isa<clang::TypeDecl>(canonicalDecl)
+                    || llvm::isa<clang::ClassTemplateDecl>(canonicalDecl)) {
+            suffix = scip::Descriptor::Type;
+          } else if (llvm::dyn_cast<clang::NamespaceDecl>(canonicalDecl)) {
+            suffix = scip::Descriptor::Namespace;
+          } else if (llvm::isa<clang::EnumConstantDecl>(canonicalDecl)
+                    || llvm::isa<clang::VarDecl>(canonicalDecl)
+                    || llvm::isa<clang::VarTemplateDecl>(canonicalDecl)) {
+            suffix = scip::Descriptor::Term;
+          } else if (auto *functionDecl = llvm::dyn_cast<clang::FunctionDecl>(canonicalDecl)) {
+            disambiguator = this->getFunctionDisambiguator(*functionDecl, buf);
+            suffix = scip::Descriptor::Method;
+          } else if (auto *funcTemplateDecl = llvm::dyn_cast<clang::FunctionTemplateDecl>(canonicalDecl)) {
+            disambiguator = this->getFunctionDisambiguator(*funcTemplateDecl->getTemplatedDecl(), buf);
+            suffix = scip::Descriptor::Method;
+          } else if (auto *usingTemplateDecl = llvm::dyn_cast<clang::TypeAliasTemplateDecl>(canonicalDecl)) {
+            canonicalDecl = usingTemplateDecl->getTemplatedDecl();
+            continue;
+          } else {
+            return {};
+          }
+          break;
+        } while (true);
+        // clang-format on
         auto descriptor = DescriptorBuilder{
             .name = this->formatTemporary(usingShadowDecl),
             .disambiguator = disambiguator,

test/index/aliases/aliases.cc

@@ -80,7 +80,33 @@ namespace z {
 namespace i {
   namespace j {
     void f() {}
+
+    template <typename T>
+    void ft(T) {}
+
+    template <typename T>
+    T zero = 0;
   }
   using j::f;
   void g() { f(); }
-}
+
+  using j::ft;
+  void gt() { ft<int>(0); }
+
+  namespace k {
+    template <typename T>
+    struct S {};
+
+    template <typename T>
+    using SAlias = S<T>;
+  }
+
+  using k::S;
+  using SS = S<int>;
+
+  using j::zero;
+  static int zero_int = zero<int>;
+
+  using k::SAlias;
+  using SAliasInt = SAlias<int>;
+}

test/index/aliases/aliases.snapshot.cc

@@ -142,6 +142,8 @@
 //                                      ^ reference local 4
       using U::identity;
 //          ^ reference [..] z/U#
+//             ^^^^^^^^ reference [..] z/U#identity(ada6a8422704cf8a).
+//             ^^^^^^^^ definition [..] z/V#identity(ada6a8422704cf8a).
     };
 
     template <typename T>
@@ -159,6 +161,7 @@
 //                 ^ definition local 6
 //                             ^ reference [..] z/W#v.
 //                               ^^^^^^^^ reference [..] z/V#identity(9b79fb6aee4c0440).
+//                               ^^^^^^^^ reference [..] z/V#identity(ada6a8422704cf8a).
 //                                        ^ reference local 5
 //                                           ^ reference local 6
     };
@@ -170,6 +173,19 @@
 //            ^ definition [..] i/j/
       void f() {}
 //         ^ definition [..] i/j/f(49f6e7a06ebc5aa8).
+  
+      template <typename T>
+//                       ^ definition local 7
+      void ft(T) {}
+//         ^^ definition [..] i/j/ft(9b289cee16747614).
+//            ^ reference local 7
+  
+      template <typename T>
+//                       ^ definition local 8
+      T zero = 0;
+//    ^ reference local 8
+//      ^^^^ definition [..] i/j/zero.
+//      ^^^^ definition [..] i/j/zero.
     }
     using j::f;
 //        ^ reference [..] i/j/
@@ -178,4 +194,46 @@
     void g() { f(); }
 //       ^ definition [..] i/g(49f6e7a06ebc5aa8).
 //             ^ reference [..] i/f(49f6e7a06ebc5aa8).
+  
+    using j::ft;
+//        ^ reference [..] i/j/
+//           ^^ definition [..] i/ft(9b289cee16747614).
+//           ^^ reference [..] i/j/ft(9b289cee16747614).
+    void gt() { ft<int>(0); }
+//       ^^ definition [..] i/gt(49f6e7a06ebc5aa8).
+//              ^^ reference [..] i/ft(9b289cee16747614).
+  
+    namespace k {
+//            ^ definition [..] i/k/
+      template <typename T>
+//                       ^ definition local 9
+      struct S {};
+//           ^ definition [..] i/k/S#
+  
+      template <typename T>
+//                       ^ definition local 10
+      using SAlias = S<T>;
+//          ^^^^^^ definition [..] i/k/SAlias#
+//                   ^ reference [..] i/k/S#
+//                     ^ reference local 10
+    }
+  
+    using k::S;
+//        ^ reference [..] i/k/
+//           ^ definition [..] i/S#
+    using SS = S<int>;
+//        ^^ definition [..] i/SS#
+  
+    using j::zero;
+//        ^ reference [..] i/j/
+//           ^^^^ definition [..] i/zero.
+    static int zero_int = zero<int>;
+//             ^^^^^^^^ definition [..] i/zero_int.
+//                        ^^^^ reference [..] i/j/zero.
+  
+    using k::SAlias;
+//        ^ reference [..] i/k/
+//           ^^^^^^ definition [..] i/SAlias#
+    using SAliasInt = SAlias<int>;
+//        ^^^^^^^^^ definition [..] i/SAliasInt#
   }