Check signature compatibility in declare_function (fixes #427)

cranelift/tests/moduletests.rs

@@ -0,0 +1,22 @@
+extern crate cranelift_codegen;
+extern crate cranelift_module;
+extern crate cranelift_simplejit;
+
+use cranelift_codegen::settings::*;
+use cranelift_codegen::ir::*;
+use cranelift_module::*;
+use cranelift_simplejit::*;
+
+#[test]
+fn error_on_incompatible_sig_in_declare_function() {
+    let mut module: Module<SimpleJITBackend> = Module::new(SimpleJITBuilder::new());
+    let mut sig = Signature {
+        params: vec![AbiParam::new(types::I64)],
+        returns: vec![],
+        call_conv: CallConv::SystemV,
+        argument_bytes: None,
+    };
+    module.declare_function("abc", Linkage::Local, &sig).unwrap();
+    sig.params[0] = AbiParam::new(types::I32);
+    module.declare_function("abc", Linkage::Local, &sig).err().unwrap(); // Make sure this is an error
+}