Add .Nil member to SymbolUntypedValue.type for nil

Change symbol for `nil` from SymbolBasicValue to SymbolUntypedValue

Enable semantic tokens for identifiers with SymbolBasicValue symbol value.
Previously I disabled it (in #263) because `nil` was included there,
which made it be highlighted as a type.

src/server/analysis.odin

@@ -335,6 +335,8 @@ is_symbol_same_typed :: proc(
 				case:
 					return false
 				}
+			case .Nil:
+				return false
 			}
 		}
 	}
@@ -1292,24 +1294,21 @@ internal_resolve_type_identifier :: proc(
 		ident := new_type(Ident, node.pos, node.end, ast_context.allocator)
 		ident.name = node.name
 
-		symbol: Symbol
+		symbol: Symbol = {
+			type = .Keyword,
+			signature = node.name,
+			name = ident.name,
+			pkg = ast_context.current_package,
+		}
 
 		switch ident.name {
 		case "true", "false":
-			symbol = Symbol {
-				type = .Keyword,
-				signature = node.name,
-				pkg = ast_context.current_package,
-				value = SymbolUntypedValue{type = .Bool},
-			}
+			symbol.value = SymbolUntypedValue{type = .Bool}
+		case "nil":
+			// TODO get the type of nil from the context and remove .Nil from SymbolUntypedValue
+			symbol.value = SymbolUntypedValue{type = .Nil}
 		case:
-			symbol = Symbol {
-				type = .Keyword,
-				signature = node.name,
-				name = ident.name,
-				pkg = ast_context.current_package,
-				value = SymbolBasicValue{ident = ident},
-			}
+			symbol.value = SymbolBasicValue{ident = ident}
 		}
 
 		return symbol, true
@@ -4375,6 +4374,8 @@ get_signature :: proc(
 			return "bool"
 		case .Integer:
 			return "int"
+		case .Nil:
+			return "" // no obvious type for nil
 		}
 	}
 

src/server/hover.odin

@@ -33,6 +33,8 @@ write_hover_content :: proc(
 			symbol.signature = "float"
 		case .Integer:
 			symbol.signature = "int"
+		case .Nil:
+			// no obvious signature for nil
 		}
 	}
 

src/server/semantic_tokens.odin

@@ -600,10 +600,11 @@ visit_ident :: proc(
 	     SymbolFixedArrayValue,
 	     SymbolSliceValue,
 	     SymbolMapValue,
-	     SymbolMultiPointer:
+	     SymbolMultiPointer,
+	     SymbolBasicValue:
 		write_semantic_node(builder, ident, .Type, modifiers)
-	case SymbolBasicValue, SymbolUntypedValue:
-		// handled by static syntax analysis
+	case SymbolUntypedValue:
+		// handled by static syntax highlighting
 	case SymbolGenericValue:
 		// unused
 	case:

src/server/symbol.odin

@@ -94,6 +94,7 @@ SymbolUntypedValue :: struct {
 		Float,
 		String,
 		Bool,
+		Nil,
 	},
 	tok:  tokenizer.Token,
 }