Diagnostics
Diagnostics
Every DUInnnn diagnostic: what it means, how it happens, how to fix it.
Every message DreamGUI gives about a .dui carries a code, DUInnnn, and is printed as File.dui(line,col): error DUI3001: …: the file, the line and the column (both counted from 1), the severity, the code, and one sentence that names the offending text -- Settings.dui(12,5): error DUI3001: 'Title' is already the id of the node on line 4, for example. When a Blueprint compiles, they appear in its compiler results. The code is the stable half: one code per cause, the same cause reached from two places keeps one code, and tests assert the code rather than the wording, so the wording stays free to improve; a retired code stays retired and is never given to anything else. The first digit says which stage refused: 1 the lexer (characters that are not a token), 2 the parser (tokens that do not form the grammar), 3 meaning (grammatical, but the tree does not hold together -- a duplicate id, an unknown type), 4 values (a value that does not fit the property it is written on), 5 building the tree (reflection refused the write, or the object to write does not exist), 6 compiling into the Blueprint (the .dui could not be attached to its Blueprint), 7 writing back (the designer could not put an edit into the text).
Severity is decided where a diagnostic is raised, not by its range. Most codes are errors, and an error fails the compile -- a file that does not parse leaves the Blueprint's previous hierarchy where it was rather than blanking it. A few are warnings -- DUI3008, DUI3013, DUI3023, DUI5007, DUI6003 -- where the file compiles and something is still worth a look. The VS Code extension reports the same codes with the same wording: what one file settles on its own (the lexer, brackets, duplicate names and so on) it checks as you type, and the rest reaches its Problems panel through DUI/.dui-diagnostics.json after the Unreal editor compiles; the compiler stays the authority.
The seven families
| Stage | Meaning | Codes | |
|---|---|---|---|
| DUI1xxx | Lexer | A character sequence that is not a token. | 7 |
| DUI2xxx | Parser | Tokens that do not form the grammar. | 20 |
| DUI3xxx | Meaning | Grammatical, but the tree does not hold together: a duplicate id, an unknown type. | 23 |
| DUI4xxx | Values | A value that does not fit the property it is written on. | 8 |
| DUI5xxx | Building the tree | Reflection refused the write, or the target object does not exist. | 22 |
| DUI6xxx | Compiling | The .dui could not be attached to its Blueprint. | 14 |
| DUI7xxx | Write-back | The designer's edit could not be put into the text. | 5 |
Every code
| Code | Name | Severity | Meaning |
|---|---|---|---|
| DUI1001 | UnexpectedCharacter | error | A character that cannot begin any token. |
| DUI1002 | UnterminatedString | error | A string that reaches the end of its line without its closing quote. |
| DUI1003 | UnterminatedComment | error | A /* that never reaches */. |
| DUI1004 | MalformedNumber | error | A number that cannot be read: two decimal points, a trailing dot, a unit glued on (24px). |
| DUI1005 | MalformedHexColor | error | A colour whose digit count is not 3, 4, 6 or 8. |
| DUI1006 | IdentifierTooLong | error | A name longer than an FName holds. |
| DUI1007 | AssetPathTooLong | error | An asset path longer than an FName holds. |
| DUI2001 | UnexpectedToken | error | A token where the grammar wants something else; the message names both. |
| DUI2002 | UnclosedBlock | error | A { with no matching }. |
| DUI2003 | UnclosedTuple | error | A ( with no matching ). |
| DUI2004 | MissingNodeId | error | A node with neither an id nor a block, or an unnamed node with (was: …). |
| DUI2005 | MissingPropertyValue | error | A property with no = or arrow, or nothing after it. |
| DUI2006 | MalformedRoot | error | No root node in a file compiled into a class, or more than one. |
| DUI2007 | MalformedClassDeclaration | error | class twice, with an empty path, or inside a node. |
| DUI2008 | MalformedWasClause | error | (was: …) holding something other than one id. |
| DUI2009 | MalformedKeyOverride | error | @key(…) holding something other than one string, or after a value that is not a string. |
| DUI2010 | MalformedLoopHeader | error | A for / each header that is not <keyword> Var in Source or Source(). |
| DUI2011 | MalformedBindingExpression | error | The right side of <-, <-> or an emit's arguments that do not parse. |
| DUI2012 | ImportFailed | error | A use that could not be honoured: no such file, unreadable, does not parse, or a cycle. |
| DUI2013 | NestingTooDeep | error | Blocks or parentheses nested deeper than 256. |
| DUI2014 | MalformedTimeline | error | A timeline block or line that is not the grammar. |
| DUI2015 | MalformedUseDeclaration | error | use … as without a name, a keyword as the name, or a class path without as. |
| DUI2016 | MalformedPropsBlock | error | A props line that is not Type Name or Type Name = value, or props inside a node. |
| DUI2017 | MalformedEventsBlock | error | An events entry that is not Name or Name(Type Param, …), or events inside a node. |
| DUI2018 | MalformedConditional | error | An if without its condition or block, an else with no if, or a branch holding something other than widgets. |
| DUI2019 | MalformedSlotDeclaration | error | A slot with default twice, or a block that both declares and fills. |
| DUI2020 | MalformedRows | error | A rows table that does not read: a column list that is not names, a column twice, a row with the wrong number of values. |
| DUI3001 | DuplicateNodeId | error | Two nodes share an id. |
| DUI3002 | InvalidNodeId | error | An id that is not an identifier, starts with a digit, or is a keyword. |
| DUI3003 | UnknownNodeType | error | A type that is no tag, container, alias, registered widget or path. |
| DUI3004 | UnknownStyle | error | : Name naming no style this file sees. |
| DUI3005 | DuplicateStyle | error | Two styles of one name in one file. |
| DUI3006 | UnknownBehaviourClass | error | + Name naming nothing a widget can carry. |
| DUI3007 | DuplicateSlotName_Retired | error | Retired; two slots of one name are DUI3001. |
| DUI3008 | ShadowedLoopVariable | warning | A loop variable that hides an enclosing loop's (a warning). |
| DUI3009 | ParentRefusedChild | error | A parent that will not take this child: a full content widget, a named slot filled twice. |
| DUI3010 | RenameOldIdStillInUse | error | (was: X) while X is still an id in the file. |
| DUI3011 | DuplicateWasId | error | Two nodes claim (was: X). |
| DUI3012 | SelfRename | error | (was: X) on the node called X. |
| DUI3013 | RenameGraphReferenceAmbiguous | warning | The old id is also another member's name, so graph references are not moved (a warning). |
| DUI3014 | DuplicateResource | error | Two resource entries of one name. |
| DUI3015 | StyleCycle | error | A style that inherits itself through its bases. |
| DUI3016 | DuplicateTimeline | error | Two timelines of one name. |
| DUI3017 | DuplicateComponentAlias | error | Two use … as lines give one name. |
| DUI3018 | AliasShadowsBuiltIn | error | A use … as name that is a tag or a container. |
| DUI3019 | DuplicateProp | error | Two props lines declare one name. |
| DUI3020 | DuplicateEvent | error | Two events entries of one name, or one parameter twice. |
| DUI3021 | UnknownNamespace | error | ns.Name whose ns no use … as ns declares. |
| DUI3022 | MultipleDefaultSlots | error | More than one slot … default in one file. |
| DUI3023 | DuplicateRowKey | warning | Warning. Two rows of a rows table whose first values make the same id; the second's id then moves with the order. |
| DUI4001 | UnknownProperty | error | No property of that name; the nearest one is suggested. |
| DUI4002 | UnknownPropertyPathSegment | error | A dotted path whose head resolves and whose tail does not. |
| DUI4003 | ValueTypeMismatch | error | A value whose shape cannot be the property's type. |
| DUI4004 | TupleArityMismatch | error | A tuple with the wrong number of elements. |
| DUI4005 | UnknownEnumValue | error | A word the property's enum does not declare. |
| DUI4006 | PropertyNotWritable | error | A property text cannot write: transient, deprecated, part of the object graph, a delegate. |
| DUI4007 | UnknownResource | error | @Name naming no resource entry. |
| DUI4008 | ResourceTypeMismatch | error | A resource whose value is not its declared type, or a non-Asset resource used as a node type. |
| DUI5001 | AssetNotFound | error | An asset or class path that does not load. |
| DUI5002 | NoVisualForProperty | error | A property of a visual the node's type does not create. |
| DUI5003 | NoPanelSlotForProperty | error | A slot line on a node whose parent lays out no panel. |
| DUI5004 | BindingFunctionNotFound | error | A bound function the class does not have, or one that takes parameters. |
| DUI5005 | BindingTargetHasNoSetter | error | A bound property with no setter. |
| DUI5006 | NotAUserWidgetClass | error | A node typed by a class that is not a concrete DreamUI user widget. |
| DUI5007 | LoopNotExpanded | warning | A loop built by a caller with nowhere to record it, and skipped (a warning). |
| DUI5008 | BindingTargetNotSupported | error | A binding on something no binding can name: a slot, a container, a field of a struct. |
| DUI5009 | NothingToBuild | error | The tree had no root; the parser said why. |
| DUI5010 | EventNotFound | error | X -> … where X is not an event of the destination. |
| DUI5011 | BindingExpressionUnsupported | error | An expression the compiler cannot turn into a function. |
| DUI5012 | EachMisplaced | error | An each at the root, nested, without a list view, or without exactly one template. |
| DUI5013 | NodeReferenceNotFound | error | A node id written as a value that names no node in the file. |
| DUI5014 | LoopBodyBindingUnsupported | error | An expression or a <-> inside a loop body. |
| DUI5015 | TimelineTargetNotFound | error | A track path that names no node. |
| DUI5016 | TimelinePropertyNotAnimatable | error | A track property no animation track can drive. |
| DUI5017 | UnknownEaseName | error | An ease name the tween library does not have. |
| DUI5018 | ComponentAliasUnresolved | error | An alias that names no class: no class line and no Blueprint for the file, or a path that loads nothing. |
| DUI5019 | SlotFillOutsideComponent | error | slot Name { … } filling a slot under a node that is not a component instance. |
| DUI5020 | UnknownSlotToFill | error | A fill naming a slot the component does not declare. |
| DUI5021 | ForMisplaced | error | A for at the root, in another loop, in a host with fixed room, or without exactly one template. |
| DUI5022 | SecondLayoutContainer | error | A second layout container on one node. |
| DUI6001 | SourceFileUnreadable | error | The Blueprint's Source File does not exist or cannot be read. |
| DUI6002 | EmptyTree | error | The file parsed and produced no tree. |
| DUI6003 | ClassPathMismatch | warning | The class line names another Blueprint than the one compiling (a warning). |
| DUI6004 | EventHandlerNotFound | error | -> Handler naming a function the class does not have. |
| DUI6005 | EventHandlerSignatureMismatch | error | A handler whose parameters are not the event's. |
| DUI6006 | EachSourceNotFound | error | A loop source the class has neither as a function nor as a variable. |
| DUI6007 | EachSourceNotObjectArray | error | A loop source that is not an array of objects. |
| DUI6008 | PropTypeUnknown | error | A props or events type with no Blueprint pin. |
| DUI6009 | PropNameTaken | error | A props name another member already has with another type, or a widget's id. |
| DUI6010 | EmitUnknownEvent | error | emit Name of an event this file does not declare. |
| DUI6011 | EmitArgumentMismatch | error | emit arguments that are not the event's parameters. |
| DUI6012 | EmitRouteUnsupported | error | An emit where no handler can be generated: in a loop body, or for an event Blueprints cannot carry. |
| DUI6013 | PropDefaultInvalid | error | A props default its type cannot hold. |
| DUI6014 | EventNameTaken | error | An events name another member of the class already answers to. |
| DUI7001 | PatchTargetNotFound | error | A designer edit with no home in the file: an unknown node, a bound property, a slot with no block. |
| DUI7002 | SourceFileChangedUnderEdit | error | The file changed under a pending edit; nothing was written. |
| DUI7003 | PatchValueNotRepresentable | error | A value the language cannot spell (a non-finite number); its line is left alone. |
| DUI7004 | PatchSyntaxNotWritable | error | An edit to something no line spells: a visibility an if decides, a shorthand that cannot be rewritten. |
| DUI7005 | PatchStyleComponentNotWritable | error | An edit to a value a style's + line gives the node; add the line to the node or change the style. |