Thread error message information for requires

compiler/can/src/module.rs

@@ -50,7 +50,7 @@ pub struct ModuleOutput {
     pub problems: Vec<Problem>,
     pub referenced_values: VecSet<Symbol>,
     pub referenced_types: VecSet<Symbol>,
-    pub symbols_from_requires: Vec<(Symbol, Loc<Type>)>,
+    pub symbols_from_requires: Vec<(Loc<Symbol>, Loc<Type>)>,
     pub scope: Scope,
 }
 
@@ -168,7 +168,7 @@ pub fn canonicalize_module_defs<'a>(
     aliases: MutMap<Symbol, Alias>,
     exposed_imports: MutMap<Ident, (Symbol, Region)>,
     exposed_symbols: &VecSet<Symbol>,
-    symbols_from_requires: &[(Symbol, Loc<TypeAnnotation<'a>>)],
+    symbols_from_requires: &[(Loc<Symbol>, Loc<TypeAnnotation<'a>>)],
     var_store: &mut VarStore,
 ) -> Result<ModuleOutput, RuntimeError> {
     let mut can_exposed_imports = MutMap::default();

compiler/constrain/src/module.rs

@@ -3,13 +3,14 @@ use roc_can::abilities::AbilitiesStore;
 use roc_can::constraint::{Constraint, Constraints};
 use roc_can::def::Declaration;
 use roc_can::expected::Expected;
+use roc_can::pattern::Pattern;
 use roc_collections::all::MutMap;
 use roc_error_macros::internal_error;
 use roc_module::symbol::{ModuleId, Symbol};
 use roc_region::all::{Loc, Region};
 use roc_types::solved_types::{FreeVars, SolvedType};
 use roc_types::subs::{VarStore, Variable};
-use roc_types::types::{Category, Type};
+use roc_types::types::{AnnotationSource, Category, Type};
 
 use crate::expr::{constrain_def_make_constraint, constrain_def_pattern, Env};
 
@@ -96,7 +97,7 @@ pub enum ExposedModuleTypes {
 
 pub fn constrain_module(
     constraints: &mut Constraints,
-    symbols_from_requires: Vec<(Symbol, Loc<Type>)>,
+    symbols_from_requires: Vec<(Loc<Symbol>, Loc<Type>)>,
     abilities_store: &AbilitiesStore,
     declarations: &[Declaration],
     home: ModuleId,
@@ -114,14 +115,14 @@ pub fn constrain_module(
 
 fn constrain_symbols_from_requires(
     constraints: &mut Constraints,
-    symbols_from_requires: Vec<(Symbol, Loc<Type>)>,
+    symbols_from_requires: Vec<(Loc<Symbol>, Loc<Type>)>,
     home: ModuleId,
     constraint: Constraint,
 ) -> Constraint {
     symbols_from_requires
         .into_iter()
-        .fold(constraint, |constraint, (symbol, loc_type)| {
+        .fold(constraint, |constraint, (loc_symbol, loc_type)| {
-            if symbol.module_id() == home {
+            if loc_symbol.value.module_id() == home {
                 // 1. Required symbols can only be specified in package modules
                 // 2. Required symbols come from app modules
                 // But, if we are running e.g. `roc check` on a package module, there is no app
@@ -130,7 +131,7 @@ fn constrain_symbols_from_requires(
                 // the types they are annotated with.
                 let rigids = Default::default();
                 let env = Env { home, rigids };
-                let pattern = Loc::at_zero(roc_can::pattern::Pattern::Identifier(symbol));
+                let pattern = Loc::at_zero(roc_can::pattern::Pattern::Identifier(loc_symbol.value));
 
                 let def_pattern_state =
                     constrain_def_pattern(constraints, &env, &pattern, loc_type.value.clone());
@@ -148,10 +149,17 @@ fn constrain_symbols_from_requires(
             } else {
                 // Otherwise, this symbol comes from an app module - we want to check that the type
                 // provided by the app is in fact what the package module requires.
+                let arity = loc_type.value.arity();
                 let provided_eq_requires_constr = constraints.lookup(
-                    symbol,
+                    loc_symbol.value,
-                    // TODO give it a real expectation, so errors can be helpful
+                    Expected::FromAnnotation(
-                    Expected::NoExpectation(loc_type.value),
+                        loc_symbol.map(|&s| Pattern::Identifier(s)),
+                        arity,
+                        AnnotationSource::TypedBody {
+                            region: loc_type.region,
+                        },
+                        loc_type.value,
+                    ),
                     loc_type.region,
                 );
                 constraints.and_constraint([provided_eq_requires_constr, constraint])

compiler/load_internal/src/file.rs

@@ -513,7 +513,7 @@ struct ModuleHeader<'a> {
     exposed_imports: MutMap<Ident, (Symbol, Region)>,
     parse_state: roc_parse::state::State<'a>,
     header_for: HeaderFor<'a>,
-    symbols_from_requires: Vec<(Symbol, Loc<TypeAnnotation<'a>>)>,
+    symbols_from_requires: Vec<(Loc<Symbol>, Loc<TypeAnnotation<'a>>)>,
     module_timing: ModuleTiming,
 }
 
@@ -604,7 +604,7 @@ struct ParsedModule<'a> {
     exposed_imports: MutMap<Ident, (Symbol, Region)>,
     parsed_defs: &'a [Loc<roc_parse::ast::Def<'a>>],
     module_name: ModuleNameEnum<'a>,
-    symbols_from_requires: Vec<(Symbol, Loc<TypeAnnotation<'a>>)>,
+    symbols_from_requires: Vec<(Loc<Symbol>, Loc<TypeAnnotation<'a>>)>,
     header_for: HeaderFor<'a>,
 }
 
@@ -3376,7 +3376,7 @@ fn send_header_two<'a>(
                 debug_assert!(!scope.contains_key(&ident.clone()));
 
                 scope.insert(ident, (symbol, entry.ident.region));
-                symbols_from_requires.push((symbol, entry.ann));
+                symbols_from_requires.push((Loc::at(entry.ident.region, symbol), entry.ann));
             }
 
             for entry in requires_types {