Don't require Store in Instance constructor (#810)

* Don't require `Store` in `Instance` constructor

This can be inferred from the `Module` argument. Additionally add a
`store` accessor to an `Instance` in case it's needed to instantiate
another `Module`.

cc #708

* Update more constructors

* Fix a doctest

* Don't ignore store in `wasm_instance_new`

* Run rustfmt

crates/api/examples/gcd.rs

@@ -50,7 +50,7 @@ fn main() -> anyhow::Result<()> {
         .0;
 
     // Instantiate the module.
-    let instance = Instance::new(&store, &module, &[])?;
+    let instance = Instance::new(&module, &[])?;
 
     // Invoke `gcd` export
     let gcd = instance.exports()[gcd_index].func().expect("gcd");

crates/api/examples/hello.rs

@@ -48,8 +48,7 @@ fn main() -> Result<()> {
     // Note that this is where the wasm `start` function, if any, would run.
     println!("Instantiating module...");
     let imports = vec![hello_func.into()];
-    let instance =
-        Instance::new(&store, &module, &imports).context("> Error instantiating module!")?;
+    let instance = Instance::new(&module, &imports).context("> Error instantiating module!")?;
 
     // Next we poke around a bit to extract the `run` function from the module.
     println!("Extracting export...");

crates/api/examples/memory.rs

@@ -90,7 +90,7 @@ fn main() -> Result<(), Error> {
 
     // Instantiate.
     println!("Instantiating module...");
-    let instance = Instance::new(&store, &module, &[]).context("> Error instantiating module!")?;
+    let instance = Instance::new(&module, &[]).context("> Error instantiating module!")?;
 
     // Extract export.
     println!("Extracting export...");

crates/api/examples/multi.rs

@@ -67,8 +67,8 @@ fn main() -> Result<()> {
     // Instantiate.
     println!("Instantiating module...");
     let imports = vec![callback_func.into()];
-    let instance = Instance::new(&store, &module, imports.as_slice())
-        .context("Error instantiating module!")?;
+    let instance =
+        Instance::new(&module, imports.as_slice()).context("Error instantiating module!")?;
 
     // Extract exports.
     println!("Extracting export...");

crates/api/src/callable.rs

@@ -59,7 +59,6 @@ use wasmtime_runtime::Export;
 ///
 /// // Create module instance that imports our function
 /// let instance = wasmtime::Instance::new(
-///     &store,
 ///     &module,
 ///     &[times_two_function.into()]
 /// )?;

crates/api/src/instance.rs

@@ -68,7 +68,8 @@ pub struct Instance {
 }
 
 impl Instance {
-    pub fn new(store: &Store, module: &Module, externs: &[Extern]) -> Result<Instance, Error> {
+    pub fn new(module: &Module, externs: &[Extern]) -> Result<Instance, Error> {
+        let store = module.store();
         let context = store.context().clone();
         let exports = store.global_exports().clone();
         let (mut instance_handle, contexts) = instantiate_in_context(
@@ -100,14 +101,27 @@ impl Instance {
         })
     }
 
-    pub fn exports(&self) -> &[Extern] {
-        &self.exports
+    /// Returns the associated [`Store`] that this `Instance` is compiled into.
+    ///
+    /// This is the [`Store`] that generally serves as a sort of global cache
+    /// for various instance-related things.
+    pub fn store(&self) -> &Store {
+        self.module.store()
     }
 
+    /// Returns the associated [`Module`] that this `Instance` instantiated.
+    ///
+    /// The corresponding [`Module`] here is a static version of this `Instance`
+    /// which can be used to learn information such as naming information about
+    /// various functions.
     pub fn module(&self) -> &Module {
         &self.module
     }
 
+    pub fn exports(&self) -> &[Extern] {
+        &self.exports
+    }
+
     pub fn find_export_by_name(&self, name: &str) -> Option<&Extern> {
         let (i, _) = self
             .module

crates/api/src/runtime.rs

@@ -397,6 +397,10 @@ impl Store {
             .get(&type_index)
             .cloned()
     }
+
+    pub(crate) fn ptr_eq(a: &Store, b: &Store) -> bool {
+        Rc::ptr_eq(&a.inner, &b.inner)
+    }
 }
 
 impl Default for Store {

crates/api/src/wasm.rs

@@ -686,7 +686,6 @@ pub unsafe extern "C" fn wasm_instance_new(
     imports: *const *const wasm_extern_t,
     result: *mut *mut wasm_trap_t,
 ) -> *mut wasm_instance_t {
-    let store = &(*store).store.borrow();
     let mut externs: Vec<Extern> = Vec::with_capacity((*module).imports.len());
     for i in 0..(*module).imports.len() {
         let import = *imports.add(i);
@@ -697,8 +696,21 @@ pub unsafe extern "C" fn wasm_instance_new(
             ExternHost::Memory(e) => Extern::Memory(e.borrow().clone()),
         });
     }
+    let store = &(*store).store.borrow();
     let module = &(*module).module.borrow();
-    match Instance::new(store, module, &externs) {
+    // FIXME(WebAssembly/wasm-c-api#126) what else can we do with the `store`
+    // argument?
+    if !Store::ptr_eq(&store, module.store()) {
+        if !result.is_null() {
+            let trap = Trap::new("wasm_store_t must match store in wasm_module_t");
+            let trap = Box::new(wasm_trap_t {
+                trap: HostRef::new(trap),
+            });
+            (*result) = Box::into_raw(trap);
+        }
+        return ptr::null_mut();
+    }
+    match Instance::new(module, &externs) {
         Ok(instance) => {
             let instance = Box::new(wasm_instance_t {
                 instance: HostRef::new(instance),

crates/api/tests/import-indexes.rs

@@ -55,7 +55,7 @@ fn same_import_names_still_distinct() -> anyhow::Result<()> {
         )
         .into(),
     ];
-    let instance = Instance::new(&store, &module, &imports)?;
+    let instance = Instance::new(&module, &imports)?;
 
     let func = instance.find_export_by_name("foo").unwrap().func().unwrap();
     let results = func.call(&[])?;

crates/api/tests/import_calling_export.rs

@@ -47,7 +47,7 @@ fn test_import_calling_export() {
 
     let imports = vec![callback_func.into()];
     let instance =
-        Instance::new(&store, &module, imports.as_slice()).expect("failed to instantiate module");
+        Instance::new(&module, imports.as_slice()).expect("failed to instantiate module");
 
     let exports = instance.exports();
     assert!(!exports.is_empty());

crates/api/tests/traps.rs

@@ -29,7 +29,7 @@ fn test_trap_return() -> Result<(), String> {
     let hello_func = Func::new(&store, hello_type, Rc::new(HelloCallback));
 
     let imports = vec![hello_func.into()];
-    let instance = Instance::new(&store, &module, &imports)
+    let instance = Instance::new(&module, &imports)
         .map_err(|e| format!("failed to instantiate module: {:?}", e))?;
     let run_func = instance.exports()[0]
         .func()

crates/fuzzing/src/oracles.rs

@@ -60,7 +60,7 @@ pub fn instantiate(wasm: &[u8], strategy: Strategy) {
     // aren't caught during validation or compilation. For example, an imported
     // table might not have room for an element segment that we want to
     // initialize into it.
-    let _result = Instance::new(&store, &module, &imports);
+    let _result = Instance::new(&module, &imports);
 }
 
 /// Compile the Wasm buffer, and implicitly fail if we have an unexpected
@@ -152,7 +152,7 @@ pub fn make_api_calls(api: crate::generators::api::ApiCalls) {
                 // aren't caught during validation or compilation. For example, an imported
                 // table might not have room for an element segment that we want to
                 // initialize into it.
-                if let Ok(instance) = Instance::new(store.as_ref().unwrap(), &module, &imports) {
+                if let Ok(instance) = Instance::new(&module, &imports) {
                     instances.insert(id, instance);
                 }
             }

crates/misc/py/src/lib.rs

@@ -120,7 +120,7 @@ pub fn instantiate(
         }
     }
 
-    let instance = wasmtime::Instance::new(&store, &module, &imports)
+    let instance = wasmtime::Instance::new(&module, &imports)
         .map_err(|t| PyErr::new::<Exception, _>(format!("instantiated with trap {:?}", t)))?;
 
     let module = Py::new(py, Module { module })?;

crates/misc/rust/macro/src/lib.rs

@@ -75,7 +75,7 @@ fn generate_load(item: &syn::ItemTrait) -> syn::Result<TokenStream> {
                 }
             }
             let instance =
-                Instance::new(&store, &module, &imports).map_err(|t| format_err!("instantiation trap: {:?}", t))?;
+                Instance::new(&module, &imports).map_err(|t| format_err!("instantiation trap: {:?}", t))?;
 
             Ok(#name { instance, data })
         }

crates/test-programs/tests/wasm_tests/runtime.rs

@@ -61,7 +61,7 @@ pub fn instantiate(data: &[u8], bin_name: &str, workspace: Option<&Path>) -> any
         })
         .collect::<Result<Vec<_>, _>>()?;
 
-    let instance = Instance::new(&store, &module, &imports).context(format!(
+    let instance = Instance::new(&module, &imports).context(format!(
         "error while instantiating Wasm module '{}'",
         bin_name,
     ))?;

crates/test-programs/wasi-tests/Cargo.lock

@@ -17,7 +17,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "wasi-tests"
-version = "0.7.0"
+version = "0.9.0"
 dependencies = [
  "libc 0.2.66 (registry+https://github.com/rust-lang/crates.io-index)",
  "more-asserts 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",

crates/wast/src/wast.rs

@@ -99,7 +99,7 @@ impl WastContext {
                 .clone();
             imports.push(export);
         }
-        let instance = match Instance::new(&self.store, &module, &imports) {
+        let instance = match Instance::new(&module, &imports) {
             Ok(i) => i,
             Err(e) => return e.downcast::<Trap>().map(Outcome::Trap),
         };

src/commands/run.rs

@@ -259,7 +259,7 @@ impl RunCommand {
             })
             .collect::<Result<Vec<_>, _>>()?;
 
-        let instance = Instance::new(store, &module, &imports)
+        let instance = Instance::new(&module, &imports)
             .context(format!("failed to instantiate {:?}", path))?;
 
         Ok((instance, module, data))

tests/custom_signal_handler.rs

@@ -108,7 +108,7 @@ mod tests {
         let store = Store::new(&engine);
         let data = wat::parse_str(WAT1)?;
         let module = Module::new(&store, &data)?;
-        let instance = Instance::new(&store, &module, &[])?;
+        let instance = Instance::new(&module, &[])?;
 
         let (base, length) = set_up_memory(&instance);
         instance.set_signal_handler(move |signum, siginfo, _| {
@@ -165,7 +165,7 @@ mod tests {
 
         // Set up multiple instances
 
-        let instance1 = Instance::new(&store, &module, &[])?;
+        let instance1 = Instance::new(&module, &[])?;
         let instance1_handler_triggered = Rc::new(AtomicBool::new(false));
 
         {
@@ -192,7 +192,7 @@ mod tests {
             });
         }
 
-        let instance2 = Instance::new(&store, &module, &[]).expect("failed to instantiate module");
+        let instance2 = Instance::new(&module, &[]).expect("failed to instantiate module");
         let instance2_handler_triggered = Rc::new(AtomicBool::new(false));
 
         {
@@ -261,7 +261,7 @@ mod tests {
         // instance1 which defines 'read'
         let data1 = wat::parse_str(WAT1)?;
         let module1 = Module::new(&store, &data1)?;
-        let instance1 = Instance::new(&store, &module1, &[])?;
+        let instance1 = Instance::new(&module1, &[])?;
         let (base1, length1) = set_up_memory(&instance1);
         instance1.set_signal_handler(move |signum, siginfo, _| {
             println!("instance1");
@@ -275,7 +275,7 @@ mod tests {
         // instance2 wich calls 'instance1.read'
         let data2 = wat::parse_str(WAT2)?;
         let module2 = Module::new(&store, &data2)?;
-        let instance2 = Instance::new(&store, &module2, &[instance1_read])?;
+        let instance2 = Instance::new(&module2, &[instance1_read])?;
         // since 'instance2.run' calls 'instance1.read' we need to set up the signal handler to handle
         // SIGSEGV originating from within the memory of instance1
         instance2.set_signal_handler(move |signum, siginfo, _| {