[lldb] Fix lookup of types in anonymous namespaces with -gsimple-template-names (#123054)

Anonymous namespaces are supposed to be optional when looking up types.
This was not working in combination with -gsimple-template-names,
because the way it was constructing the complete (with template args)
name scope (i.e., by generating thescope as a string and then reparsing
it) did not preserve the information about the scope kinds.

Essentially what the code wants here is to call `GetTypeLookupContext`
(that's the function used to get the context in the "regular" code
path), but to embelish each name with the template arguments (if they
don't have them already). This PR implements exactly that by adding an
argument to control which kind of names are we interested in. This
should also make the lookup faster as it avoids parsing of the long
string, but I haven't attempted to benchmark that.

I believe this function can also be used in some other places where
we're manually appending template names, but I'm leaving that for
another patch.

Author: labath

lldb/source/Plugins/SymbolFile/DWARF/DWARFDIE.cpp

@@ -19,6 +19,8 @@
 #include "llvm/ADT/iterator.h"
 #include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/DebugInfo/DWARF/DWARFAddressRange.h"
+#include "llvm/DebugInfo/DWARF/DWARFTypePrinter.h"
+#include "llvm/Support/raw_ostream.h"
 
 using namespace lldb_private;
 using namespace lldb_private::dwarf;
@@ -376,7 +378,8 @@ lldb_private::Type *DWARFDIE::ResolveTypeUID(const DWARFDIE &die) const {
   return nullptr;
 }
 
-static CompilerContext GetContextEntry(DWARFDIE die) {
+static CompilerContext GetContextEntry(DWARFDIE die,
+                                       bool derive_template_names) {
   auto ctx = [die](CompilerContextKind kind) {
     return CompilerContext(kind, ConstString(die.GetName()));
   };
@@ -386,11 +389,6 @@ static CompilerContext GetContextEntry(DWARFDIE die) {
     return ctx(CompilerContextKind::Module);
   case DW_TAG_namespace:
     return ctx(CompilerContextKind::Namespace);
-  case DW_TAG_class_type:
-  case DW_TAG_structure_type:
-    return ctx(CompilerContextKind::ClassOrStruct);
-  case DW_TAG_union_type:
-    return ctx(CompilerContextKind::Union);
   case DW_TAG_enumeration_type:
     return ctx(CompilerContextKind::Enum);
   case DW_TAG_subprogram:
@@ -401,12 +399,28 @@ static CompilerContext GetContextEntry(DWARFDIE die) {
     return ctx(CompilerContextKind::Typedef);
   case DW_TAG_base_type:
     return ctx(CompilerContextKind::Builtin);
+  case DW_TAG_class_type:
+  case DW_TAG_structure_type:
+  case DW_TAG_union_type: {
+    CompilerContextKind kind = die.Tag() == DW_TAG_union_type
+                                   ? CompilerContextKind::Union
+                                   : CompilerContextKind::ClassOrStruct;
+    llvm::StringRef name = die.GetName();
+    if (!derive_template_names || name.contains('<'))
+      return CompilerContext(kind, ConstString(name));
+
+    std::string name_storage = name.str();
+    llvm::raw_string_ostream os(name_storage);
+    llvm::DWARFTypePrinter<DWARFDIE>(os).appendAndTerminateTemplateParameters(
+        die);
+    return CompilerContext(kind, ConstString(os.str()));
+  }
   default:
     llvm_unreachable("Check tag type in the caller!");
   }
 }
 
-static void GetDeclContextImpl(DWARFDIE die,
+static void GetDeclContextImpl(DWARFDIE die, bool derive_template_names,
                                llvm::SmallSet<lldb::user_id_t, 4> &seen,
                                std::vector<CompilerContext> &context) {
   // Stop if we hit a cycle.
@@ -428,7 +442,7 @@ static void GetDeclContextImpl(DWARFDIE die,
     case DW_TAG_subprogram:
     case DW_TAG_variable:
     case DW_TAG_typedef:
-      context.push_back(GetContextEntry(die));
+      context.push_back(GetContextEntry(die, derive_template_names));
       break;
     default:
       break;
@@ -438,15 +452,16 @@ static void GetDeclContextImpl(DWARFDIE die,
   }
 }
 
-std::vector<CompilerContext> DWARFDIE::GetDeclContext() const {
+std::vector<CompilerContext>
+DWARFDIE::GetDeclContext(bool derive_template_names) const {
   llvm::SmallSet<lldb::user_id_t, 4> seen;
   std::vector<CompilerContext> context;
-  GetDeclContextImpl(*this, seen, context);
+  GetDeclContextImpl(*this, derive_template_names, seen, context);
   std::reverse(context.begin(), context.end());
   return context;
 }
 
-static void GetTypeLookupContextImpl(DWARFDIE die,
+static void GetTypeLookupContextImpl(DWARFDIE die, bool derive_template_names,
                                      llvm::SmallSet<lldb::user_id_t, 4> &seen,
                                      std::vector<CompilerContext> &context) {
   // Stop if we hit a cycle.
@@ -461,7 +476,7 @@ static void GetTypeLookupContextImpl(DWARFDIE die,
     case DW_TAG_variable:
     case DW_TAG_typedef:
     case DW_TAG_base_type:
-      context.push_back(GetContextEntry(die));
+      context.push_back(GetContextEntry(die, derive_template_names));
       break;
 
     // If any of the tags below appear in the parent chain, stop the decl
@@ -484,10 +499,11 @@ static void GetTypeLookupContextImpl(DWARFDIE die,
   }
 }
 
-std::vector<CompilerContext> DWARFDIE::GetTypeLookupContext() const {
+std::vector<CompilerContext>
+DWARFDIE::GetTypeLookupContext(bool derive_template_names) const {
   llvm::SmallSet<lldb::user_id_t, 4> seen;
   std::vector<CompilerContext> context;
-  GetTypeLookupContextImpl(*this, seen, context);
+  GetTypeLookupContextImpl(*this, derive_template_names, seen, context);
   std::reverse(context.begin(), context.end());
   return context;
 }

lldb/source/Plugins/SymbolFile/DWARF/DWARFDIE.h

@@ -73,7 +73,15 @@ class DWARFDIE : public DWARFBaseDIE {
   /// Return this DIE's decl context as it is needed to look up types
   /// in Clang modules. This context will include any modules or functions that
   /// the type is declared in so an exact module match can be efficiently made.
-  std::vector<CompilerContext> GetDeclContext() const;
+  ///
+  /// \param[in] derive_template_names
+  ///   If true, augments the returned names with template arguments derived
+  ///   from the child DIEs, if the names don't contained template arguments
+  ///   already. If false, the returned context will contain the names exactly
+  ///   as they are spelled in the debug info, regardless of whether that
+  ///   includes template arguments or not.
+  std::vector<CompilerContext>
+  GetDeclContext(bool derive_template_names = false) const;
 
   /// Get a context to a type so it can be looked up.
   ///
@@ -85,7 +93,15 @@ class DWARFDIE : public DWARFBaseDIE {
   /// appropriate time, like either the translation unit or at a function
   /// context. This is designed to allow users to efficiently look for types
   /// using a full or partial CompilerContext array.
-  std::vector<CompilerContext> GetTypeLookupContext() const;
+  ///
+  /// \param[in] derive_template_names
+  ///   If true, augments the returned names with template arguments derived
+  ///   from the child DIEs, if the names don't contained template arguments
+  ///   already. If false, the returned context will contain the names exactly
+  ///   as they are spelled in the debug info, regardless of whether that
+  ///   includes template arguments or not.
+  std::vector<CompilerContext>
+  GetTypeLookupContext(bool derive_template_names = false) const;
 
   DWARFDeclContext GetDWARFDeclContext() const;
 

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp

@@ -10,10 +10,8 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/DebugInfo/DWARF/DWARFAddressRange.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugLoc.h"
-#include "llvm/DebugInfo/DWARF/DWARFTypePrinter.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/FileUtilities.h"
-#include "llvm/Support/Format.h"
 #include "llvm/Support/FormatAdapters.h"
 #include "llvm/Support/Threading.h"
 
@@ -2740,18 +2738,11 @@ void SymbolFileDWARF::FindTypes(const TypeQuery &query, TypeResults &results) {
       // Copy our match's context and update the basename we are looking for
       // so we can use this only to compare the context correctly.
       m_index->GetTypesWithQuery(query_simple, [&](DWARFDIE die) {
-        // Check the language, but only if we have a language filter.
-        if (query.HasLanguage()) {
-          if (!query.LanguageMatches(GetLanguageFamily(*die.GetCU())))
-            return true; // Keep iterating over index types, language mismatch.
-        }
-
-        std::string qualified_name;
-        llvm::raw_string_ostream os(qualified_name);
-        llvm::DWARFTypePrinter<DWARFDIE> type_printer(os);
-        type_printer.appendQualifiedName(die);
-        TypeQuery die_query(qualified_name, e_exact_match);
-        if (query.ContextMatches(die_query.GetContextRef()))
+        std::vector<CompilerContext> qualified_context =
+            query.GetModuleSearch()
+                ? die.GetDeclContext(/*derive_template_names=*/true)
+                : die.GetTypeLookupContext(/*derive_template_names=*/true);
+        if (query.ContextMatches(qualified_context))
           if (Type *matching_type = ResolveType(die, true, true))
             results.InsertUnique(matching_type->shared_from_this());
         return !results.Done(query); // Keep iterating if we aren't done.

lldb/test/API/lang/cpp/nested-template/TestNestedTemplate.py

@@ -17,6 +17,16 @@ def do_test(self, debug_flags):
             DATA_TYPES_DISPLAYED_CORRECTLY,
             substrs=["1 match found"],
         )
+        self.expect(
+            "image lookup -A -t 'NS::Struct<int>'",
+            DATA_TYPES_DISPLAYED_CORRECTLY,
+            substrs=["1 match found"],
+        )
+        self.expect(
+            "image lookup -A -t 'NS::Union<int>'",
+            DATA_TYPES_DISPLAYED_CORRECTLY,
+            substrs=["1 match found"],
+        )
 
     @skipIf(compiler=no_match("clang"))
     @skipIf(compiler_version=["<", "15.0"])

lldb/test/API/lang/cpp/nested-template/main.cpp

@@ -5,6 +5,15 @@ struct Outer {
   struct Inner {};
 };
 
+namespace NS {
+namespace {
+template <typename T> struct Struct {};
+template <typename T> struct Union {};
+} // namespace
+} // namespace NS
+
 int main() {
   Outer::Inner<int> oi;
+  NS::Struct<int> ns_struct;
+  NS::Union<int> ns_union;
 }