add dealias for Resolver.

include/AST/Resolver.h

@@ -40,8 +40,14 @@ public:
                 const clang::IdentifierInfo* II,
                 llvm::ArrayRef<clang::TemplateArgument> arguments);
 
-    // replace the template arguments in the type, using the arguments in the frame
-    clang::Decl* substitute(clang::Decl* decl);
+    /// we use `Sema::SubstType` to substitute the template arguments in dependent type.
+    /// but it doesn't substitute the template arguments in alias type.
+    /// i.e. `typename base::type`, when base is `std::vector<T>`, it will ignore the `T`.
+    /// so before actually substituting the type, we need to dealias the type.
+    clang::QualType dealias(clang::QualType type);
+
+    /// replace the template arguments in the type, using the arguments in the frame
+    clang::QualType substitute(clang::QualType type);
 
 private:
     struct Frame {

src/AST/Resolver.cpp

@@ -3,11 +3,10 @@
 namespace clice {
 
 clang::QualType DependentNameResolver::resolve(clang::NamedDecl* ND) {
-    auto decl = substitute(ND);
-    if(auto TAD = llvm::dyn_cast<clang::TypeAliasDecl>(decl)) {
-        return resolve(TAD->getUnderlyingType());
-    } else if(auto TND = llvm::dyn_cast<clang::TypedefNameDecl>(decl)) {
-        return resolve(TND->getUnderlyingType());
+    if(auto TAD = llvm::dyn_cast<clang::TypeAliasDecl>(ND)) {
+        return resolve(substitute(TAD->getUnderlyingType()));
+    } else if(auto TND = llvm::dyn_cast<clang::TypedefNameDecl>(ND)) {
+        return resolve(substitute(TND->getUnderlyingType()));
     } else {
         std::terminate();
     }
@@ -127,7 +126,40 @@ bool DependentNameResolver::lookup(llvm::SmallVector<clang::NamedDecl*>& result,
     return false;
 }
 
-clang::Decl* DependentNameResolver::substitute(clang::Decl* decl) {
+// FIXME: handle more case
+static bool isalias(clang::QualType type) {
+    if(!type->isDependentType()) {
+        return false;
+    }
+
+    if(auto TAT = type->getAs<clang::TypedefType>()) {
+        return true;
+    } else if(auto DNT = type->getAs<clang::TemplateSpecializationType>()) {
+        return false;
+    } else if(auto DNT = type->getAs<clang::DependentNameType>()) {
+        return isalias(clang::QualType(DNT->getQualifier()->getAsType(), 0));
+    } else {
+        std::terminate();
+    }
+}
+
+clang::QualType DependentNameResolver::dealias(clang::QualType type) {
+    if(!isalias(type)) {
+        return type;
+    }
+
+    if(auto TAT = type->getAs<clang::TypedefType>()) {
+        return dealias(TAT->getDecl()->getUnderlyingType());
+    } else if(auto DNT = type->getAs<clang::DependentNameType>()) {
+        auto type = dealias(clang::QualType(DNT->getQualifier()->getAsType(), 0));
+        auto prefix = clang::NestedNameSpecifier::Create(context, nullptr, false, type.getTypePtr());
+        return context.getDependentNameType(DNT->getKeyword(), prefix, DNT->getIdentifier());
+    } else {
+        std::terminate();
+    }
+}
+
+clang::QualType DependentNameResolver::substitute(clang::QualType type) {
     clang::MultiLevelTemplateArgumentList list;
     for(auto begin = frames.rbegin(), end = frames.rend(); begin != end; ++begin) {
         list.addOuterTemplateArguments(begin->decl, begin->arguments, true);
@@ -141,10 +173,7 @@ clang::Decl* DependentNameResolver::substitute(clang::Decl* decl) {
         sema.pushCodeSynthesisContext(context);
     }
 
-    // FIXME: use global TU may result misunderstanding result
-    // create some fake namespace to avoid this
-    auto result = sema.SubstDecl(decl, context.getTranslationUnitDecl(), list);
-
+    auto result = sema.SubstType(dealias(type), list, {}, {});
     frames.clear();
 
     return result;

tests/Resolver.cpp

@@ -97,7 +97,6 @@ template <typename X>
 struct test {
     using result = typename C<X>::type;
 };
-
 )";
     Visitor visitor(code);
     clang::QualType result = visitor.test();
@@ -129,7 +128,6 @@ template <typename X>
 struct test {
     using result = typename A<X>::self::self::self::self::self::type;
 };
-
 )";
     Visitor visitor(code);
     clang::QualType result = visitor.test();
@@ -146,5 +144,41 @@ struct test {
     ASSERT_EQ(T->getDecl()->getName(), "X");
 }
 
+TEST(DependentNameResolver, alias_dependent_name) {
+    const char* code = R"(
+template <typename ...Ts>
+struct type_list {};
+
+template <typename T1>
+struct A {
+    using type = type_list<T1>;
+};
+
+template <typename T2>
+struct B {
+    using base = A<T2>;
+    using type = typename base::type;
+};
+
+template <typename X>
+struct test {
+    using result = typename B<X>::type;
+};
+)";
+    Visitor visitor(code);
+    clang::QualType result = visitor.test();
+    // result->dump();
+    auto TST = result->getAs<clang::TemplateSpecializationType>();
+    ASSERT_TRUE(TST);
+    ASSERT_EQ(TST->getTemplateName().getAsTemplateDecl()->getName(), "type_list");
+
+    auto args = TST->template_arguments();
+    ASSERT_EQ(args.size(), 1);
+
+    auto T = llvm::dyn_cast<clang::TemplateTypeParmType>(args[0].getAsType());
+    ASSERT_TRUE(T);
+    ASSERT_EQ(T->getDecl()->getName(), "X");
+}
+
 }  // namespace