idea (rejected): only generate work up to constraint gen, then look at what modules are actually used and generate Solve.. work based on that

cli/src/build.rs

@@ -157,6 +157,8 @@ pub fn build_file<'a>(
 
         buf.push('\n');
 
+        dbg!(module_id);
+
         report_timing(buf, "Read .roc file from disk", module_timing.read_roc_file);
         report_timing(buf, "Parse header", module_timing.parse_header);
         report_timing(buf, "Parse body", module_timing.parse_body);

compiler/constrain/src/module.rs

@@ -32,13 +32,21 @@ impl ExposedByModule {
     ///
     /// Useful when we know what modules a particular module imports, and want just
     /// the exposed types for those exposed modules.
-    pub fn retain_modules<'a>(&self, it: impl Iterator<Item = &'a ModuleId>) -> Self {
+    pub fn retain_modules<'a>(
+        &self,
+        home: ModuleId,
+        it: impl Iterator<Item = &'a ModuleId>,
+    ) -> Self {
         let mut output = Self::default();
 
         for module_id in it {
             match self.exposed.get(module_id) {
                 None => {
-                    internal_error!("Module {:?} did not register its exposed values", module_id)
+                    internal_error!(
+                        "Module {:?} did not register its exposed values for {:?}",
+                        module_id,
+                        home,
+                    )
                 }
                 Some(exposed_types) => {
                     output.exposed.insert(*module_id, exposed_types.clone());

compiler/load/src/file.rs

@@ -1099,7 +1099,7 @@ fn load<'a>(
 ) -> Result<LoadResult<'a>, LoadingProblem<'a>> {
     // When compiling to wasm, we cannot spawn extra threads
     // so we have a single-threaded implementation
-    if true || cfg!(target_family = "wasm") {
+    if cfg!(target_family = "wasm") {
         load_single_threaded(
             arena,
             load_start,
@@ -1614,14 +1614,18 @@ fn report_unused_imported_modules<'a>(
     state: &mut State<'a>,
     module_id: ModuleId,
     constrained_module: &ConstrainedModule,
-) {
+) -> (Vec<ModuleId>, Vec<ModuleId>) {
+    let mut kept = vec![];
+    let mut removed = vec![];
     let mut unused_imported_modules = constrained_module.imported_modules.clone();
 
     for symbol in constrained_module.module.referenced_values.iter() {
+        kept.push(symbol.module_id());
         unused_imported_modules.remove(&symbol.module_id());
     }
 
     for symbol in constrained_module.module.referenced_types.iter() {
+        kept.push(symbol.module_id());
         unused_imported_modules.remove(&symbol.module_id());
     }
 
@@ -1633,8 +1637,23 @@ fn report_unused_imported_modules<'a>(
     for (unused, region) in unused_imported_modules.drain() {
         if !unused.is_builtin() {
             existing.push(roc_problem::can::Problem::UnusedImport(unused, region));
+
+            // we will still typecheck this module to report errors
+            kept.push(unused)
+        } else {
+            // for builtin modules, we will just skip the rest of the process
+            // in the future, we can also do this for modules from packages
+            removed.push(unused);
         }
     }
+
+    kept.sort();
+    kept.dedup();
+
+    removed.sort();
+    removed.dedup();
+
+    (kept, removed)
 }
 
 fn update<'a>(
@@ -1870,7 +1889,7 @@ fn update<'a>(
             work.extend(state.dependencies.add_module(
                 header.module_id,
                 &header.package_qualified_imported_modules,
-                state.goal_phase,
+                Phase::CanonicalizeAndConstrain,
             ));
 
             state.module_cache.headers.insert(header.module_id, header);
@@ -1919,7 +1938,7 @@ fn update<'a>(
         }
 
         CanonicalizedAndConstrained {
-            constrained_module,
+            mut constrained_module,
             canonicalization_problems,
             module_docs,
         } => {
@@ -1934,7 +1953,51 @@ fn update<'a>(
                 state.module_cache.documentation.insert(module_id, docs);
             }
 
-            report_unused_imported_modules(&mut state, module_id, &constrained_module);
+            let (kept, removed) =
+                report_unused_imported_modules(&mut state, module_id, &constrained_module);
+
+            for rem in removed {
+                constrained_module.imported_modules.remove(&rem);
+            }
+
+            use std::fmt::Write;
+            let mut buf = String::new();
+            writeln!(buf, "{:?} depends on:", module_id);
+            for dep in kept {
+                if !constrained_module.imported_modules.contains_key(&dep) {
+                    continue;
+                }
+                writeln!(buf, "     {:?} ", dep);
+                if module_id != dep {
+                    state
+                        .dependencies
+                        .add_dependency(module_id, dep, Phase::SolveTypes);
+                }
+            }
+            println!("{}", buf);
+
+            state.dependencies.add_dependency_help(
+                module_id,
+                module_id,
+                Phase::SolveTypes,
+                Phase::CanonicalizeAndConstrain,
+            );
+
+            state
+                .dependencies
+                .add_to_status(module_id, Phase::SolveTypes);
+
+            /*
+            for dependency in remove_dependencies {
+                println!("remove dep {:?} <- {:?}", module_id, dependency);
+                state.dependencies.remove_dependencies(
+                    module_id,
+                    dependency,
+                    Phase::SolveTypes,
+                    state.goal_phase,
+                );
+            }
+            */
 
             state
                 .module_cache
@@ -1996,7 +2059,7 @@ fn update<'a>(
 
             if is_host_exposed && state.goal_phase == Phase::SolveTypes {
                 debug_assert!(work.is_empty());
-                debug_assert!(state.dependencies.solved_all());
+                // debug_assert!(state.dependencies.solved_all());
 
                 state.timings.insert(module_id, module_timing);
 
@@ -2787,10 +2850,7 @@ fn load_module<'a>(
                     roc_parse::header::ModuleName::new("Bool"),
                     Collection::with_items(&[Loc::at_zero(Spaced::Item(ExposedName::new("Bool")))]),
                 )),
-                Loc::at_zero(ImportsEntry::Module(
-                    roc_parse::header::ModuleName::new("List"),
-                    Collection::with_items(&[Loc::at_zero(Spaced::Item(ExposedName::new("List")))]),
-                )),
+                // Note: List is only used for the type, which we ensure is always in scope
                 Loc::at_zero(ImportsEntry::Module(
                     roc_parse::header::ModuleName::new("Num"),
                     Collection::with_items(&[
@@ -2856,9 +2916,6 @@ fn load_module<'a>(
 
                 toUtf8 : Str -> List U8
 
-                # fromUtf8 : List U8 -> Result Str [ BadUtf8 Utf8Problem ]*
-                # fromUtf8Range : List U8 -> Result Str [ BadUtf8 Utf8Problem Nat, OutOfBounds ]*
-
                 fromUtf8 : List U8 -> Result Str [ BadUtf8 Utf8ByteProblem Nat ]*
                 fromUtf8Range : List U8, { start : Nat, count : Nat } -> Result Str [ BadUtf8 Utf8ByteProblem Nat, OutOfBounds ]*
 
@@ -4344,7 +4401,8 @@ impl<'a> BuildTask<'a> {
         dep_idents: MutMap<ModuleId, IdentIds>,
         declarations: Vec<Declaration>,
     ) -> Self {
-        let exposed_by_module = exposed_types.retain_modules(imported_modules.keys());
+        let exposed_by_module =
+            exposed_types.retain_modules(module.module_id, imported_modules.keys());
         let exposed_for_module =
             ExposedForModule::new(module.referenced_values.iter(), exposed_by_module);
 
@@ -4635,6 +4693,10 @@ fn canonicalize_and_constrain<'a>(
             let constraint =
                 constrain_module(&mut constraints, &module_output.declarations, module_id);
 
+            if module_id == ModuleId::STR {
+                dbg!(&constraints);
+            }
+
             let after = roc_types::types::get_type_clone_count();
 
             log!(

compiler/load/src/work.rs

@@ -32,7 +32,7 @@ enum Status {
     Done,
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 enum Job<'a> {
     Step(ModuleId, Phase),
     ResolveShorthand(&'a str),
@@ -74,8 +74,10 @@ impl<'a> Dependencies<'a> {
             // to canonicalize a module, all its dependencies must be canonicalized
             self.add_dependency(module_id, dep, Phase::CanonicalizeAndConstrain);
 
-            // to typecheck a module, all its dependencies must be type checked already
-            self.add_dependency(module_id, dep, Phase::SolveTypes);
+            if goal_phase >= Phase::SolveTypes {
+                // to typecheck a module, all its dependencies must be type checked already
+                self.add_dependency(module_id, dep, Phase::SolveTypes);
+            }
 
             if goal_phase >= FindSpecializations {
                 self.add_dependency(module_id, dep, Phase::FindSpecializations);
@@ -101,7 +103,7 @@ impl<'a> Dependencies<'a> {
         output
     }
 
-    fn add_to_status(&mut self, module_id: ModuleId, goal_phase: Phase) {
+    pub fn add_to_status(&mut self, module_id: ModuleId, goal_phase: Phase) {
         for phase in PHASES.iter() {
             if *phase > goal_phase {
                 break;
@@ -193,13 +195,72 @@ impl<'a> Dependencies<'a> {
         }
     }
 
+    pub fn remove_dependencies(
+        &mut self,
+        a: ModuleId,
+        b: ModuleId,
+        start_phase: Phase,
+        goal_phase: Phase,
+    ) {
+        let mut i = 0;
+        while PHASES[i] < goal_phase {
+            let phase = PHASES[i];
+
+            if phase >= start_phase {
+                self.remove_dependency(a, b, phase);
+            }
+
+            i += 1;
+        }
+    }
+
     /// A waits for B, and B will notify A when it completes the phase
-    fn add_dependency(&mut self, a: ModuleId, b: ModuleId, phase: Phase) {
+    /// we will remove both of these connections
+    fn remove_dependency(&mut self, a: ModuleId, b: ModuleId, phase: Phase) {
+        let key = Job::Step(a, phase);
+
+        let mut notifications = vec![];
+
+        match self.waiting_for.get_mut(&key) {
+            None => unreachable!(),
+            Some(x) => {
+                x.retain(|job| match job {
+                    Job::Step(module, _) => {
+                        if *module == b {
+                            notifications.push(*job);
+                            false
+                        } else {
+                            true
+                        }
+                    }
+                    Job::ResolveShorthand(_) => true,
+                });
+            }
+        }
+
+        for notification in notifications {
+            match self.notifies.get_mut(&notification) {
+                None => unreachable!(),
+                Some(x) => {
+                    x.retain(|notify_job| notify_job != &key);
+                }
+            }
+        }
+    }
+
+    /// A waits for B, and B will notify A when it completes the phase
+    pub fn add_dependency(&mut self, a: ModuleId, b: ModuleId, phase: Phase) {
         self.add_dependency_help(a, b, phase, phase);
     }
 
     /// phase_a of module a is waiting for phase_b of module_b
-    fn add_dependency_help(&mut self, a: ModuleId, b: ModuleId, phase_a: Phase, phase_b: Phase) {
+    pub fn add_dependency_help(
+        &mut self,
+        a: ModuleId,
+        b: ModuleId,
+        phase_a: Phase,
+        phase_b: Phase,
+    ) {
         // no need to wait if the dependency is already done!
         if let Some(Status::Done) = self.status.get(&Job::Step(b, phase_b)) {
             return;

compiler/module/src/symbol.rs

@@ -293,7 +293,7 @@ lazy_static! {
 }
 
 /// A globally unique ID that gets assigned to each module as it is loaded.
-#[derive(Copy, Clone, PartialEq, Eq, Hash)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub struct ModuleId(u32);
 
 impl ModuleId {