GHC.Tc.Types.ErrCtxt

In an expression.

In a user-written context.

In a quantified constraint.

When checking an inferred type.

In an inline pragma, or a fixity signature, or a type signature, or... (see Sig).

In a user-written type signature.

In a record update.

In a class method.

In the instance type signature of a class method.

In a pattern type signature.

In a pattern.

In a pattern synonym declaration.

In a pattern matching context, e.g. a equation for a function binding, or a case alternative, ...

In a match in a pattern matching context, either for an expression or for an arrow command.

In a function application.

In a function call.

In the result of a function call.

In the declaration of a type constructor.

In a type or data family instance (or default instance).

In the declaration of a data constructor.

In the result type of a data constructor.

In the equations for a closed type family.

In the expansion of a type synonym.

In a role annotation.

In an arrow command.

In an instance declaration.

In a default declaration.

In the body of a static form.

In a pattern binding.

In a foreign import/export declaration.

In a record field.

In a type.

In a kind.

In an ambiguity check.

In a term-level use of a Name.

When checking the type of the main function.

Warning emitted when inferring use of visible dependent quantification.

In a statement

In patten of the do statement. (c.f. MonadFailErrors)

In an rebindable syntax expression.

In a RULE.

In a subtype check.

In an export.

In an export of a pattern synonym.

In an export of a pattern synonym record field.

In an annotation.

In a specialise pragma.

In a deriving clause.

In a standalone deriving clause.

When typechecking the body of a derived instance.

In an untyped Template Haskell quote.

In a typed Template Haskell quote.

In an untyped Template Haskell splice or quasi-quote.

In a typed Template Haskell splice.

In the result of a typed Template Haskell splice.

In an argument to the Template Haskell reifyInstances function.

While merging Backpack signatures.

While checking that a module implements a Backpack signature.

Don't report redundant constraints

Report redundant constraints The SrcSpan is for the constraints E.g. f :: (Eq a, Ord b) => blah The span is for the (Eq a, Ord b) We need to record the span here because we have long since discarded the HsType in favour of a Type