From 31cefbdf0364a3d224420365049885051734669b Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Wed, 4 Mar 2020 21:36:41 +0000
Subject: Cache imports correctly

---
 dhall/build.rs                         |  3 ---
 dhall/src/error/mod.rs                 |  4 ++--
 dhall/src/semantics/resolve/env.rs     | 24 ++++++++++++------------
 dhall/src/semantics/resolve/resolve.rs | 14 +++++++-------
 dhall/tests/import/failure/cycle.txt   |  2 +-
 5 files changed, 22 insertions(+), 25 deletions(-)

diff --git a/dhall/build.rs b/dhall/build.rs
index 565c37e..4bd56a3 100644
--- a/dhall/build.rs
+++ b/dhall/build.rs
@@ -324,9 +324,6 @@ fn generate_tests() -> std::io::Result<()> {
                     // Too slow, but also not all features implemented
                     // For now needs support for hashed imports
                     || path == "prelude"
-                    // TODO: remote imports
-                    || path == "CacheImports"
-                    || path == "CacheImportsCanonicalize"
             }),
             input_type: FileType::Text,
             output_type: Some(FileType::Text),
diff --git a/dhall/src/error/mod.rs b/dhall/src/error/mod.rs
index 29dd5ad..6dd8393 100644
--- a/dhall/src/error/mod.rs
+++ b/dhall/src/error/mod.rs
@@ -1,6 +1,6 @@
 use std::io::Error as IOError;
 
-use crate::semantics::resolve::ImportStack;
+use crate::semantics::resolve::{ImportLocation, ImportStack};
 use crate::syntax::{Import, ParseError};
 
 mod builder;
@@ -29,7 +29,7 @@ pub(crate) enum ImportError {
     Missing,
     MissingEnvVar,
     UnexpectedImport(Import<()>),
-    ImportCycle(ImportStack, Import<()>),
+    ImportCycle(ImportStack, ImportLocation),
     Url(url::ParseError),
 }
 
diff --git a/dhall/src/semantics/resolve/env.rs b/dhall/src/semantics/resolve/env.rs
index 43676cc..2342dcc 100644
--- a/dhall/src/semantics/resolve/env.rs
+++ b/dhall/src/semantics/resolve/env.rs
@@ -1,7 +1,7 @@
 use std::collections::HashMap;
 
 use crate::error::{Error, ImportError};
-use crate::semantics::{AlphaVar, Import, TypedHir, VarEnv};
+use crate::semantics::{AlphaVar, ImportLocation, TypedHir, VarEnv};
 use crate::syntax::{Label, V};
 
 /// Environment for resolving names.
@@ -10,8 +10,8 @@ pub(crate) struct NameEnv {
     names: Vec<Label>,
 }
 
-pub(crate) type ImportCache = HashMap<Import, TypedHir>;
-pub(crate) type ImportStack = Vec<Import>;
+pub(crate) type ImportCache = HashMap<ImportLocation, TypedHir>;
+pub(crate) type ImportStack = Vec<ImportLocation>;
 
 /// Environment for resolving imports
 #[derive(Debug, Clone)]
@@ -74,28 +74,28 @@ impl ImportEnv {
 
     pub fn handle_import(
         &mut self,
-        import: Import,
-        mut do_resolve: impl FnMut(&mut Self, &Import) -> Result<TypedHir, Error>,
+        location: ImportLocation,
+        do_resolve: impl FnOnce(&mut Self) -> Result<TypedHir, Error>,
     ) -> Result<TypedHir, Error> {
-        if self.stack.contains(&import) {
+        if self.stack.contains(&location) {
             return Err(
-                ImportError::ImportCycle(self.stack.clone(), import).into()
+                ImportError::ImportCycle(self.stack.clone(), location).into()
             );
         }
-        Ok(match self.cache.get(&import) {
+        Ok(match self.cache.get(&location) {
             Some(expr) => expr.clone(),
             None => {
                 // Push the current import on the stack
-                self.stack.push(import.clone());
+                self.stack.push(location);
 
                 // Resolve the import recursively
-                let expr = do_resolve(self, &import)?;
+                let expr = do_resolve(self)?;
 
                 // Remove import from the stack.
-                self.stack.pop();
+                let location = self.stack.pop().unwrap();
 
                 // Add the import to the cache
-                self.cache.insert(import, expr.clone());
+                self.cache.insert(location, expr.clone());
 
                 expr
             }
diff --git a/dhall/src/semantics/resolve/resolve.rs b/dhall/src/semantics/resolve/resolve.rs
index 782f5f7..d8115f8 100644
--- a/dhall/src/semantics/resolve/resolve.rs
+++ b/dhall/src/semantics/resolve/resolve.rs
@@ -22,7 +22,7 @@ pub(crate) type Import = syntax::Import<()>;
 pub(crate) type TypedHir = (Hir, Type);
 
 /// The location of some data, usually some dhall code.
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub(crate) enum ImportLocation {
     /// Local file
     Local(PathBuf),
@@ -143,9 +143,8 @@ fn make_aslocation_uniontype() -> Expr {
 fn resolve_one_import(
     env: &mut ImportEnv,
     import: &Import,
-    location: &ImportLocation,
+    location: ImportLocation,
 ) -> Result<TypedHir, Error> {
-    let location = location.chain(&import.location)?;
     match import.mode {
         ImportMode::Code => {
             let parsed = match location {
@@ -189,7 +188,7 @@ fn resolve_one_import(
                     ("Local", Some(path.to_string_lossy().into_owned()))
                 }
                 ImportLocation::Remote(url) => {
-                    ("Remote", Some(url.to_string()))
+                    ("Remote", Some(url.into_string()))
                 }
                 ImportLocation::Env(name) => ("Environment", Some(name)),
                 ImportLocation::Missing => ("Missing", None),
@@ -299,11 +298,12 @@ fn resolve_with_env(
     env: &mut ImportEnv,
     parsed: Parsed,
 ) -> Result<Resolved, Error> {
-    let Parsed(expr, root) = parsed;
+    let Parsed(expr, location) = parsed;
     let resolved =
         traverse_resolve_expr(&mut NameEnv::new(), &expr, &mut |import| {
-            env.handle_import(import, |env, import| {
-                resolve_one_import(env, import, &root)
+            let location = location.chain(&import.location)?;
+            env.handle_import(location.clone(), |env| {
+                resolve_one_import(env, &import, location)
             })
         })?;
     Ok(Resolved(resolved))
diff --git a/dhall/tests/import/failure/cycle.txt b/dhall/tests/import/failure/cycle.txt
index 4e9488e..f5a1abf 100644
--- a/dhall/tests/import/failure/cycle.txt
+++ b/dhall/tests/import/failure/cycle.txt
@@ -1 +1 @@
-ImportCycle([Import { mode: Code, location: Local(Parent, FilePath { file_path: ["data", "cycle.dhall"] }), hash: None }, Import { mode: Code, location: Local(Parent, FilePath { file_path: ["failure", "cycle.dhall"] }), hash: None }], Import { mode: Code, location: Local(Parent, FilePath { file_path: ["data", "cycle.dhall"] }), hash: None })
+ImportCycle([Local("./dhall-lang/tests/import/data/cycle.dhall"), Local("./dhall-lang/tests/import/failure/cycle.dhall")], Local("./dhall-lang/tests/import/data/cycle.dhall"))
-- 
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