Add options for parsing test files (#942)

* Add options for parsing test files

This change allows adding parsing parameters more easily; e.g. a parameter is needed for setting the default calling convention for functions parsed as a part of the `run` test feature.

* Set default calling convention that of the host for `test run` file tests

Previously `test run` used the parser's hard-coded CallConv::Fast as the default calling convention but with this change any test being `run` will use the default calling convention of the machine running the test. `test run` will now throw an error if the calling convention of the function does not match the host's.

cranelift/filetests/src/runone.rs

@@ -8,8 +8,8 @@ use cranelift_codegen::print_errors::pretty_verifier_error;
 use cranelift_codegen::settings::Flags;
 use cranelift_codegen::timing;
 use cranelift_codegen::verify_function;
-use cranelift_reader::parse_test;
 use cranelift_reader::IsaSpec;
+use cranelift_reader::{parse_test, ParseOptions};
 use log::info;
 use std::borrow::Cow;
 use std::fs;
@@ -33,8 +33,13 @@ pub fn run(path: &Path, passes: Option<&[String]>, target: Option<&str>) -> Test
     info!("---\nFile: {}", path.to_string_lossy());
     let started = time::Instant::now();
     let buffer = read_to_string(path).map_err(|e| e.to_string())?;
+    let options = ParseOptions {
+        target,
+        passes,
+        ..ParseOptions::default()
+    };
 
-    let testfile = match parse_test(&buffer, passes, target) {
+    let testfile = match parse_test(&buffer, options) {
         Ok(testfile) => testfile,
         Err(e) => {
             if e.is_warning {