[lldb] Reduce duplication in two of DWARFDIE context functions (#122712)

This doesn't make much of a difference now, but it makes it easier to
add -gsimple-template-names support to these functions (the idea is to
add an argument to say whether you want the name as spelled in the debug
info, or the one embellished with template arguments -- we have use
cases for both).

Author: labath

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

@@ -376,6 +376,36 @@ lldb_private::Type *DWARFDIE::ResolveTypeUID(const DWARFDIE &die) const {
   return nullptr;
 }
 
+static CompilerContext GetContextEntry(DWARFDIE die) {
+  auto ctx = [die](CompilerContextKind kind) {
+    return CompilerContext(kind, ConstString(die.GetName()));
+  };
+
+  switch (die.Tag()) {
+  case DW_TAG_module:
+    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:
+    return ctx(CompilerContextKind::Function);
+  case DW_TAG_variable:
+    return ctx(CompilerContextKind::Variable);
+  case DW_TAG_typedef:
+    return ctx(CompilerContextKind::Typedef);
+  case DW_TAG_base_type:
+    return ctx(CompilerContextKind::Builtin);
+  default:
+    llvm_unreachable("Check tag type in the caller!");
+  }
+}
+
 static void GetDeclContextImpl(DWARFDIE die,
                                llvm::SmallSet<lldb::user_id_t, 4> &seen,
                                std::vector<CompilerContext> &context) {
@@ -388,34 +418,17 @@ static void GetDeclContextImpl(DWARFDIE die,
     }
 
     // Add this DIE's contribution at the end of the chain.
-    auto push_ctx = [&](CompilerContextKind kind, llvm::StringRef name) {
-      context.push_back({kind, ConstString(name)});
-    };
     switch (die.Tag()) {
     case DW_TAG_module:
-      push_ctx(CompilerContextKind::Module, die.GetName());
-      break;
     case DW_TAG_namespace:
-      push_ctx(CompilerContextKind::Namespace, die.GetName());
-      break;
     case DW_TAG_class_type:
     case DW_TAG_structure_type:
-      push_ctx(CompilerContextKind::ClassOrStruct, die.GetName());
-      break;
     case DW_TAG_union_type:
-      push_ctx(CompilerContextKind::Union, die.GetName());
-      break;
     case DW_TAG_enumeration_type:
-      push_ctx(CompilerContextKind::Enum, die.GetName());
-      break;
     case DW_TAG_subprogram:
-      push_ctx(CompilerContextKind::Function, die.GetName());
-      break;
     case DW_TAG_variable:
-      push_ctx(CompilerContextKind::Variable, die.GetName());
-      break;
     case DW_TAG_typedef:
-      push_ctx(CompilerContextKind::Typedef, die.GetName());
+      context.push_back(GetContextEntry(die));
       break;
     default:
       break;
@@ -439,32 +452,18 @@ static void GetTypeLookupContextImpl(DWARFDIE die,
   // Stop if we hit a cycle.
   while (die && seen.insert(die.GetID()).second) {
     // Add this DIE's contribution at the end of the chain.
-    auto push_ctx = [&](CompilerContextKind kind, llvm::StringRef name) {
-      context.push_back({kind, ConstString(name)});
-    };
     switch (die.Tag()) {
     case DW_TAG_namespace:
-      push_ctx(CompilerContextKind::Namespace, die.GetName());
-      break;
     case DW_TAG_class_type:
     case DW_TAG_structure_type:
-      push_ctx(CompilerContextKind::ClassOrStruct, die.GetName());
-      break;
     case DW_TAG_union_type:
-      push_ctx(CompilerContextKind::Union, die.GetName());
-      break;
     case DW_TAG_enumeration_type:
-      push_ctx(CompilerContextKind::Enum, die.GetName());
-      break;
     case DW_TAG_variable:
-      push_ctx(CompilerContextKind::Variable, die.GetName());
-      break;
     case DW_TAG_typedef:
-      push_ctx(CompilerContextKind::Typedef, die.GetName());
-      break;
     case DW_TAG_base_type:
-      push_ctx(CompilerContextKind::Builtin, die.GetName());
+      context.push_back(GetContextEntry(die));
       break;
+
     // If any of the tags below appear in the parent chain, stop the decl
     // context and return. Prior to these being in here, if a type existed in a
     // namespace "a" like "a::my_struct", but we also have a function in that