Add negative tests for compact imports (#2408)

Assert that when the feature is disabled the new binary forms are rejected.

Author: alexcrichton

crates/wasmparser/src/readers/core/imports.rs

@@ -93,8 +93,15 @@ impl<'a> FromReader<'a> for Imports<'a> {
         let module = reader.read_string()?;
         let single_item_name = reader.read_string()?;
         let discriminator = reader.peek_bytes(1)?[0];
-        match (single_item_name, discriminator, reader.compact_imports()) {
-            ("", 0x7F, true) => {
+        match (single_item_name, discriminator) {
+            ("", 0x7F) => {
+                if !reader.compact_imports() {
+                    bail!(
+                        reader.original_position(),
+                        "invalid leading byte 0x7F with compact imports \
+                         proposal disabled"
+                    );
+                }
                 // Compact encoding 1: one module name, many item names / types
                 reader.read_bytes(1)?;
                 // FIXME(#188) shouldn't need to skip here
@@ -111,7 +118,14 @@ impl<'a> FromReader<'a> for Imports<'a> {
                     items: SectionLimited::new(items)?,
                 })
             }
-            ("", 0x7E, true) => {
+            ("", 0x7E) => {
+                if !reader.compact_imports() {
+                    bail!(
+                        reader.original_position(),
+                        "invalid leading byte 0x7E with compact imports \
+                         proposal disabled"
+                    );
+                }
                 // Compact encoding 2: one module name / type, many item names
                 reader.read_bytes(1)?;
                 let ty: TypeRef = reader.read()?;

tests/cli/compact-imports/compact-imports-rejected.wast

@@ -0,0 +1,22 @@
+;; RUN: wast --assert default --snapshot tests/snapshots % -f=-compact-imports
+
+(assert_malformed
+  (module
+    (import "test"
+      (item "fi32" (func (result i32)))
+      (item "fi64" (func (result i64)))
+    )
+  )
+  "invalid leading byte 0x7F with compact imports proposal disabled")
+
+(assert_malformed
+  (module
+    (import "test"
+      (item "g1")
+      (item "g20")
+      (item "g300")
+      (item "g4000")
+      (global i32)
+    )
+  )
+  "invalid leading byte 0x7E with compact imports proposal disabled")

tests/snapshots/cli/compact-imports/compact-imports-rejected.wast.json

@@ -0,0 +1,19 @@
+{
+  "source_filename": "tests/cli/compact-imports/compact-imports-rejected.wast",
+  "commands": [
+    {
+      "type": "assert_malformed",
+      "line": 4,
+      "filename": "compact-imports-rejected.0.wasm",
+      "module_type": "binary",
+      "text": "invalid leading byte 0x7F with compact imports proposal disabled"
+    },
+    {
+      "type": "assert_malformed",
+      "line": 13,
+      "filename": "compact-imports-rejected.1.wasm",
+      "module_type": "binary",
+      "text": "invalid leading byte 0x7E with compact imports proposal disabled"
+    }
+  ]
+}