All Diagnostics

Complete reference of every diagnostic code. For an introduction to how diagnostics work and how to configure them, see the Diagnostics guide.

Warning severity

Code	Description
deprecated	Usage of @deprecated symbols
discard-returns	Ignoring @nodiscard return values
type-mismatch	Argument type vs @param mismatch (including generic type arguments, e.g. Container<number> vs Container<boolean>)
return-mismatch	Return type vs @return mismatch
field-type-mismatch	Field assignment vs @field type mismatch
assign-type-mismatch	Reassignment vs @type mismatch
generic-constraint-mismatch	Generic argument doesn't satisfy class or keyof constraint
param-constraint-mismatch	Method called when the receiver's @requires type-param constraint isn't satisfied
missing-parameter	Missing required function arguments
redundant-parameter	Extra function arguments
missing-return-value	Return with fewer values than @return
redundant-return-value	Return with more values than @return
grouped-return-mismatch	Return values don't match any tuple-union @return case
missing-return	Function missing return statement
undefined-global	Reference to unresolved global name
undefined-field	Accessing nonexistent field on @class
need-check-nil	Field/method access on possibly-nil value (off by default)
nil-index	Bracket-indexing a table with a possibly-nil key (off by default)
nil-table-key	Table key type annotation includes nil (table<string?, V>)
access-private	Accessing @field private from outside
access-protected	Accessing @field protected from outside hierarchy (also _-prefixed fields when implicit_protected_prefix is enabled)
duplicate-index	Duplicate keys in table constructors
redundant-value	Extra values in assignments
unbalanced-assignments	More variables than values in assignments, including when a function call returns fewer values than variables assigned
missing-fields	Missing required fields when constructing @class tables
undefined-doc-class	Undefined class name in @class Foo: Parent
undefined-doc-name	Undefined type name in annotations
undefined-doc-param	@param name not matching function parameters
duplicate-doc-param	Duplicate @param annotations
duplicate-doc-field	Duplicate @field annotations
duplicate-doc-alias	Duplicate @alias declarations
doc-field-no-class	@field on a non-@class table
doc-func-no-function	Function-level annotation (@param, @return, etc.) not attached to a function definition
circle-doc-class	Circular @class inheritance chains
malformed-annotation	Unknown or incomplete ---@ annotations
multi-return-projection	returns<F> discards extra return values from F
builds-field-not-self	@builds-field method uses @return ClassName instead of @return self
unknown-diag-code	Unknown code in @diagnostic directives
duplicate-constructor	Multiple @constructor on a single class
constructor-return	@constructor with return other than @return self
count-down-loop	For-loop step direction doesn't match start/end
wrong-flavor-api	API not available in all declared flavors
redundant-class-generic	Method redeclares class-level @generic
cannot-call	Calling a value whose type is not callable
invalid-op	Operator applied to incompatible types (e.g. + on strings instead of ..) (off by default)
create-global	Implicit global creation
invalid-class-parent	Inheriting from a non-table type (number, string, literals, etc.)
mixed-enum-values	@enum with mixed number/string values or unsupported value types

Hint severity

Code	Description
return-self-class-name	Method uses @return ClassName instead of @return self
unused-local	Unreferenced local variables
unused-function	Unused function definitions (off by default)
unused-vararg	Function declares ... but never uses it (off by default)
redefined-local	Same-scope local variable redefinition
shadowed-local	Local variable shadows an outer-scope variable
inject-field	Setting undeclared fields on @class tables
duplicate-set-field	Setting an already-set field on @class tables
unreachable-code	Code after return
code-after-break	Code after break
incomplete-signature-doc	Partial @param/@return annotations (off by default)
empty-block	Empty control flow body
redundant-return	Bare return at end of function
trailing-space	Line ends with whitespace
not-precedence	not x <cmp> y is (not x) <cmp> y
redundant-or	or where left side is always truthy (RHS is dead code) (off by default)
redundant-and	and where left side is always falsy (RHS is dead code) or always truthy (operator is a no-op) (off by default)
redundant-condition	if/elseif/while condition is provably constant (off by default)
implicit-nil-return	Bare return in function with optional @return (off by default)
unknown-param-type	Parameter type can't be inferred (off by default)
unknown-return-type	Return value has no resolvable type (off by default)
unknown-local-type	Local assignment has unknown type (off by default)
unknown-field-type	Field assignment has unknown type (off by default)

redundant-condition

Flags if/elseif/while/repeat...until conditions that are provably always true or always false. Detected patterns:

• Always-truthy/falsy type — the condition's resolved type is guaranteed truthy (e.g. table, number) or guaranteed falsy (nil).
• Negation of a constant — not expr where expr is itself always truthy or always falsy (e.g. if not tbl where tbl is a table).
• Type-incompatible equality — ==/~= between values whose types can never match at runtime (e.g. num == "hello", nonNilVar == nil).
• Literal-union miss — x == "c" where x is typed as "a"|"b" and "c" is not a member.
• Two-literal comparison — both sides are concrete literals (e.g. 1 == 2, "a" == "a", 3 < 2).
• Self-comparison — x < x or x > x (always false; NaN-safe). <=/>=/==/~= self-comparisons are excluded because NaN breaks them.
• Redundant type() guard — type(x) == "number" where x is already known to be a number (always true) or can never be a number (always false).

Loop idioms (while true, repeat...until false) are not flagged. Conditions referencing variables reassigned inside loops are suppressed to avoid false positives.

unused-function

Flags function definitions that are never referenced anywhere in the workspace. Covers both top-level global functions and methods defined on tables (e.g. function NS.Method()).

What counts as "used":

• Called directly via call_resolutions (handles deep type inference, self-calls, etc.)
• Referenced as a value (e.g. passed as a callback, stored in a variable) — detected via field-access token resolution with inheritance

What is skipped (not flagged):

• Functions whose name starts with _ (convention for intentionally unused)
• Functions defined in library files (directories marked with library in .wowluarc.json)
• Interface methods — if 2+ distinct tables define the same method name, the method is assumed to be a framework callback pattern (duck-typing dispatch)
• Inherited methods — if a parent class's field is referenced, child overrides are also considered used

Cross-file behavior:

This diagnostic requires a multi-file workspace scan. It compares definitions from all files against references from all files. In single-file mode (e.g. evaluate), only per-file unused functions are detected.

TOC file diagnostics

These diagnostics apply to .toc files only. See the TOC Files guide for details.

Code	Severity	Description
toc-missing-interface	Warning	Required ## Interface: field is missing
toc-duplicate-header	Warning	Same header key appears more than once
toc-unknown-header	Hint	Header not in the known catalog and not X-*
toc-invalid-interface	Error	Interface value is not a valid numeric version
toc-nonexistent-file	Warning	Referenced file does not exist on disk
toc-invalid-value	Warning	Value doesn't match expected format

LuaLS compatibility aliases

Alias	Maps to
invisible	access-private, access-protected
param-type-mismatch	type-mismatch
return-type-mismatch	return-mismatch