Add constraint inference

checker/specification/specification.md

@@ -4599,10 +4599,10 @@ proxy1 satisfies { c: "d" };
 ```ts
 function makeObservable(obj, cb: (kind: string, prop: string, value: any) => void) {
 	return new Proxy(obj, {
-		get(on, prop: string, _rec) {
+		get(on: { [a: string]: any }, prop: string, _rec) {
 			cb("get", prop, on[prop])
 		},
-		set(on, prop: string, _value, _rec) {
+		set(on: { [a: string]: any }, prop: string, _value, _rec) {
 			cb("set", prop, on[prop])
 		},
 	})

checker/specification/staging.md

@@ -1,3 +1,45 @@
 Currently implementing:
 
 > This file is for work-in-progress and can help separating features that are being implemented to regressions
+
+### Constraint inference
+
+> Aka backwards inference
+
+#### From argument
+
+```ts
+function cos(a) {
+    return Math.cos(a)
+}
+
+cos satisfies (a: number) => number;
+cos(2);
+cos("hi")
+```
+
+- Argument of type "hi" is not assignable to parameter of type number
+
+#### Property access
+
+```ts
+function printName(a) {
+    return a.name
+}
+
+printName satisfies string;
+```
+
+- Expected string, found (a: { name: any }) => any
+
+#### Function call
+
+```ts
+function printName(a) {
+    return a(1, 2)
+}
+
+printName satisfies string;
+```
+
+- Expected string, found (a: (a: 1, b: 2) => any) => any

checker/src/context/environment.rs

@@ -1098,6 +1098,7 @@ impl<'a> Environment<'a> {
 					others: SubTypingOptions::default(),
 					// TODO don't think there is much case in constraining it here
 					object_constraints: None,
+					constraint_inference_requests: Some(Vec::new()),
 				};
 
 				let result =

checker/src/context/mod.rs

@@ -171,6 +171,8 @@ pub struct Context<T: ContextType> {
 	pub possibly_mutated_objects: HashMap<TypeId, TypeId>,
 	pub possibly_mutated_variables: HashSet<VariableId>,
 
+	pub constraint_inference_requests: crate::Map<TypeId, TypeId>,
+
 	// pub (crate) info: info,
 	pub info: LocalInformation,
 }
@@ -565,6 +567,7 @@ impl<T: ContextType> Context<T> {
 			info: Default::default(),
 			possibly_mutated_objects: Default::default(),
 			possibly_mutated_variables: Default::default(),
+			constraint_inference_requests: Default::default(),
 		}
 	}
 
@@ -608,6 +611,7 @@ impl<T: ContextType> Context<T> {
 			mut info,
 			possibly_mutated_objects,
 			possibly_mutated_variables,
+			constraint_inference_requests,
 		} = new_environment;
 
 		// if let Some(self_state) = self.context_type.get_state_mut() {
@@ -621,6 +625,8 @@ impl<T: ContextType> Context<T> {
 		self.possibly_mutated_objects.extend(possibly_mutated_objects);
 		self.possibly_mutated_variables.extend(possibly_mutated_variables);
 
+		self.constraint_inference_requests.extend(constraint_inference_requests);
+
 		// TODO
 		// self.tasks_to_run.extend(tasks_to_run.into_iter());
 

checker/src/context/root.rs

@@ -116,6 +116,7 @@ impl RootContext {
 			info,
 			possibly_mutated_objects: Default::default(),
 			possibly_mutated_variables: Default::default(),
+			constraint_inference_requests: Default::default(),
 		}
 	}
 

checker/src/events/application.rs

@@ -606,6 +606,7 @@ pub(crate) fn apply_events(
 										contributions: None,
 										object_constraints: None,
 										others: crate::subtyping::SubTypingOptions::default(),
+										constraint_inference_requests: None,
 									};
 
 									let result = type_is_subtype(

checker/src/features/functions.rs

@@ -833,6 +833,7 @@ where
 		// 	function.get_name()
 		// );
 
+		// Marked here as mutating things here
 		let info = function_environment.info;
 		let variable_names = function_environment.variable_names;
 
@@ -849,6 +850,7 @@ where
 						others: crate::subtyping::SubTypingOptions::default(),
 						// TODO don't think there is much case in constraining it here
 						object_constraints: None,
+						constraint_inference_requests: None,
 					};
 
 					let result = crate::subtyping::type_is_subtype(
@@ -891,22 +893,23 @@ where
 			TypeId::UNDEFINED_TYPE
 		};
 
+		// Constraint inference here
 		{
 			// let mut _back_requests = HashMap::<(), ()>::new();
-			// for (on, to) in requests {
-			// 	let type_to_alter = checking_data.types.get_type_by_id(on);
-			// 	if let Type::RootPolyType(
-			// 		PolyNature::Parameter { .. } | PolyNature::FreeVariable { .. },
-			// 	) = type_to_alter
-			// 	{
-			// 		checking_data.types.set_inferred_constraint(on, to);
-			// 	} else if let Type::Constructor(constructor) = type_to_alter {
-			// 		crate::utilities::notify!("TODO constructor {:?}", constructor);
-			// 	} else {
-			// 		crate::utilities::notify!("TODO {:?}", type_to_alter);
-			// 	}
-			// 	crate::utilities::notify!("TODO temp, setting inferred constraint. No nesting");
-			// }
+			for (on, to) in function_environment.constraint_inference_requests {
+				let type_to_alter = checking_data.types.get_type_by_id(on);
+				if let Type::RootPolyType(
+					PolyNature::Parameter { .. } | PolyNature::FreeVariable { .. },
+				) = type_to_alter
+				{
+					checking_data.types.set_inferred_constraint(on, to);
+				} else if let Type::Constructor(constructor) = type_to_alter {
+					crate::utilities::notify!("TODO constructor {:?}", constructor);
+				} else {
+					crate::utilities::notify!("TODO {:?}", type_to_alter);
+				}
+				crate::utilities::notify!("TODO temp, setting inferred constraint. No nesting");
+			}
 		}
 
 		// TODO this fixes prototypes and properties being lost during printing and subtyping of the return type

checker/src/features/mod.rs

@@ -561,6 +561,7 @@ pub mod tsc {
 			contributions: Default::default(),
 			others: subtyping::SubTypingOptions { allow_errors: false },
 			object_constraints: None,
+			constraint_inference_requests: None,
 		};
 
 		let result = subtyping::type_is_subtype(

checker/src/synthesis/functions.rs

@@ -764,6 +764,7 @@ pub(super) fn build_overloaded_function(
 						contributions: None,
 						object_constraints: None,
 						others: Default::default(),
+						constraint_inference_requests: None,
 					},
 					environment,
 					types,
@@ -805,6 +806,7 @@ pub(super) fn build_overloaded_function(
 					contributions: None,
 					object_constraints: None,
 					others: Default::default(),
+					constraint_inference_requests: None,
 				},
 				environment,
 				types,

checker/src/synthesis/type_annotations.rs

@@ -175,60 +175,67 @@ pub fn synthesise_type_annotation<T: crate::ReadFromFS>(
 											&mut checking_data.types,
 										)
 									} else {
-										synthesise_type_annotation(
+										let argument = synthesise_type_annotation(
 											argument_type_annotation,
 											environment,
 											checking_data,
-										)
-									};
-
-									{
-										use crate::types::subtyping;
-
-										let mut state = subtyping::State {
-											already_checked: Default::default(),
-											mode: Default::default(),
-											contributions: Default::default(),
-											others: subtyping::SubTypingOptions {
-												allow_errors: true,
-											},
-											object_constraints: None,
-										};
-
-										let result = subtyping::type_is_subtype(
-											parameter_restriction,
-											argument,
-											&mut state,
-											environment,
-											&checking_data.types,
 										);
 
-										if let subtyping::SubTypeResult::IsNotSubType(_matches) =
-											result
 										{
-											let error =
-												TypeCheckError::GenericArgumentDoesNotMeetRestriction {
-													parameter_restriction:
-														TypeStringRepresentation::from_type_id(
-															parameter_restriction,
+											use crate::types::subtyping;
+
+											let mut state = subtyping::State {
+												already_checked: Default::default(),
+												mode: Default::default(),
+												contributions: Default::default(),
+												others: subtyping::SubTypingOptions {
+													allow_errors: true,
+												},
+												object_constraints: None,
+												constraint_inference_requests: None,
+											};
+
+											let result = subtyping::type_is_subtype(
+												parameter_restriction,
+												argument,
+												&mut state,
+												environment,
+												&checking_data.types,
+											);
+
+											if let subtyping::SubTypeResult::IsNotSubType(
+												_matches,
+											) = result
+											{
+												let error =
+													TypeCheckError::GenericArgumentDoesNotMeetRestriction {
+														parameter_restriction:
+															TypeStringRepresentation::from_type_id(
+																parameter_restriction,
+																environment,
+																&checking_data.types,
+																checking_data.options.debug_types,
+															),
+														argument: TypeStringRepresentation::from_type_id(
+															argument,
 															environment,
 															&checking_data.types,
 															checking_data.options.debug_types,
 														),
-													argument: TypeStringRepresentation::from_type_id(
-														argument,
-														environment,
-														&checking_data.types,
-														checking_data.options.debug_types,
-													),
-													position: argument_type_annotation
-														.get_position()
-														.with_source(environment.get_source()),
-												};
-
-											checking_data.diagnostics_container.add_error(error);
+														position: argument_type_annotation
+															.get_position()
+															.with_source(environment.get_source()),
+													};
+
+												checking_data
+													.diagnostics_container
+													.add_error(error);
+											}
 										}
-									}
+
+										argument
+									};
+
 									let position = argument_type_annotation
 										.get_position()
 										.with_source(environment.get_source());