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Merged
merged 3 commits into from
Jul 11, 2025
Merged

Allow platform-dependent snapshot test results #1270

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e09c41f
transpile: snapshot: build to stdout rather than creating+deleting rlib
fw-immunant Jul 10, 2025
9caf93c
transpile: snapshot: allow platform-dependent snapshots
fw-immunant Jul 10, 2025
5044813
transpile: snapshots: add dummy files so insta::glob sees multiple tests
fw-immunant Jul 10, 2025
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59 changes: 26 additions & 33 deletions c2rust-transpile/tests/snapshots.rs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
use std::env::current_dir;
use std::ffi::OsString;
use std::fs;
use std::path::{Path, PathBuf};
use std::path::Path;
use std::process::Command;

use c2rust_transpile::{ReplaceMode, TranspilerConfig};
Expand Down Expand Up @@ -47,22 +46,7 @@ fn config() -> TranspilerConfig {
}
}

fn transpile(c_path: &Path) {
let parent_dir_name = c_path
.parent()
.and_then(|dir| dir.file_name())
.and_then(|file_name| file_name.to_str())
.unwrap_or_default();
// Some things transpile differently on Linux vs. macOS,
// as they use `unsigned long` and `unsigned long long` differently for builtins.
// This makes snapshot tests trickier, as the output will be OS-dependent.
// We only test Linux here, as that should be sufficient for these specific tests,
// and because cross-compiling with transpilation is not super straightforward,
// so generating the macOS snapshots locally on Linux is annoying.
if parent_dir_name == "linux" && !cfg!(target_os = "linux") {
return;
}

fn transpile(platform: Option<&str>, c_path: &Path) {
let status = Command::new("clang")
.args(&["-c", "-o", "/dev/null"])
.arg(c_path)
Expand All @@ -77,28 +61,37 @@ fn transpile(c_path: &Path) {
let rs_path = c_path.with_extension("rs");
let rs = fs::read_to_string(&rs_path).unwrap();
let debug_expr = format!("cat {}", rs_path.display());
insta::assert_snapshot!("transpile", &rs, &debug_expr);

let name = platform
.map(|platform| ["transpile", platform].join("-"))
.unwrap_or("transpile".into());

insta::assert_snapshot!(name, &rs, &debug_expr);

let status = Command::new("rustc")
.args(&["--crate-type", "lib", "--edition", "2021"])
.args(&["--crate-type", "lib", "--edition", "2021", "-o", "-"])
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Ah this is a lot simpler way of doing this. This writes to stout? How does that work vs /dev/null?

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/dev/null would be a more obvious bit-bucket, but rustc attempts to create temporary files in the output directory and can't for /dev.

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What gets printed to stdout with -?

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@fw-immunant fw-immunant Jul 10, 2025 •
edited
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The --emit=link contents, whatever they are. In this case the output is not captured, so it doesn't really matter what it is.

.arg(&rs_path)
.status();
assert!(status.unwrap().success());
let rlib_path = {
let mut file_name = OsString::new();
file_name.push("lib");
file_name.push(rs_path.file_stem().unwrap());
file_name.push(".rlib");
PathBuf::from(file_name)
};
fs::remove_file(&rlib_path).unwrap();
}

#[test]
fn transpile_all() {
// We need to do this as a single glob,
// as `insta` removes the common prefix to all matches files,
// and if we do this as separate globs (for linux-only files),
// they'll overwrite each other.
insta::glob!("snapshots/**/*.c", transpile);
insta::glob!("snapshots/*.c", |x| transpile(None, x));

// Some things transpile differently on Linux vs. macOS,
// as they use `unsigned long` and `unsigned long long` differently for builtins.
// This makes snapshot tests trickier, as the output will be OS-dependent.
// We handle this by adding OS name to the snapshot result filename.
#[allow(unused)]
let platform = "unknown";

#[cfg(target_os = "linux")]
let platform = "linux";
#[cfg(target_os = "macos")]
let platform = "macos";

insta::with_settings!({snapshot_suffix => platform}, {
insta::glob!("snapshots/platform-specific/*.c", |x| transpile(Some(platform), x));
});
}
2 changes: 2 additions & 0 deletions c2rust-transpile/tests/snapshots/platform-specific/dummy.c
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
/* empty file until we have multiple tests; if we glob only one test, insta
omits the `@file.c` suffix from snapshots */
9 changes: 9 additions & 0 deletions c2rust-transpile/tests/snapshots/platform-specific/dummy.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
#![allow(
dead_code,
mutable_transmutes,
non_camel_case_types,
non_snake_case,
non_upper_case_globals,
unused_assignments,
unused_mut
)]
0 ...-transpile/tests/snapshots/linux/rotate.c → ...ests/snapshots/platform-specific/rotate.c
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File renamed without changes.
0 ...transpile/tests/snapshots/linux/rotate.rs → ...sts/snapshots/platform-specific/rotate.rs
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File renamed without changes.
16 changes: 16 additions & 0 deletions c2rust-transpile/tests/snapshots/[email protected]
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Original file line number Diff line number Diff line change
@@ -0,0 +1,16 @@
---
source: c2rust-transpile/tests/snapshots.rs
assertion_line: 69
expression: cat tests/snapshots/platform-specific/dummy.rs
input_file: c2rust-transpile/tests/snapshots/platform-specific/dummy.c
---
#![allow(
dead_code,
mutable_transmutes,
non_camel_case_types,
non_snake_case,
non_upper_case_globals,
unused_assignments,
unused_mut
)]

6 changes: 4 additions & 2 deletions ...snapshots__transpile@linux__rotate.c.snap → .../[email protected]
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Original file line number Diff line number Diff line change
@@ -1,7 +1,8 @@
---
source: c2rust-transpile/tests/snapshots.rs
expression: cat tests/snapshots/linux/rotate.rs
input_file: c2rust-transpile/tests/snapshots/linux/rotate.c
assertion_line: 67
expression: cat tests/snapshots/platform-specific/rotate.rs
input_file: c2rust-transpile/tests/snapshots/platform-specific/rotate.c
---
#![allow(
dead_code,
Expand All @@ -28,3 +29,4 @@ pub unsafe extern "C" fn rotate_right_64(
.rotate_right(4 as std::ffi::c_int as std::ffi::c_ulong as u32)
as std::ffi::c_ulonglong;
}

16 changes: 16 additions & 0 deletions c2rust-transpile/tests/snapshots/[email protected]
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Original file line number Diff line number Diff line change
@@ -0,0 +1,16 @@
---
source: c2rust-transpile/tests/snapshots.rs
assertion_line: 69
expression: cat tests/snapshots/platform-specific/dummy.rs
input_file: c2rust-transpile/tests/snapshots/platform-specific/dummy.c
---
#![allow(
dead_code,
mutable_transmutes,
non_camel_case_types,
non_snake_case,
non_upper_case_globals,
unused_assignments,
unused_mut
)]

28 changes: 28 additions & 0 deletions c2rust-transpile/tests/snapshots/[email protected]
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Original file line number Diff line number Diff line change
@@ -0,0 +1,28 @@
---
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How do we generate the macOS snapshots on Linux easily?

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There's no way to do so from Linux without a macOS VM; we need to compile against Apple's proprietary (though nominally open-source) headers. If we want to support macOS, this is the price we pay.

We could improve the workflow by having snapshot .new files produced as an artifact from our macOS CI pipeline.

source: c2rust-transpile/tests/snapshots.rs
assertion_line: 67
expression: cat tests/snapshots/platform-specific/rotate.rs
input_file: c2rust-transpile/tests/snapshots/platform-specific/rotate.c
---
#![allow(
dead_code,
mutable_transmutes,
non_camel_case_types,
non_snake_case,
non_upper_case_globals,
unused_assignments,
unused_mut
)]
#[no_mangle]
pub unsafe extern "C" fn rotate_left_64(
mut x: std::ffi::c_ulonglong,
) -> std::ffi::c_ulonglong {
return x.rotate_left(4 as std::ffi::c_int as std::ffi::c_ulonglong as u32);
}
#[no_mangle]
pub unsafe extern "C" fn rotate_right_64(
mut x: std::ffi::c_ulonglong,
) -> std::ffi::c_ulonglong {
return x.rotate_right(4 as std::ffi::c_int as std::ffi::c_ulonglong as u32);
}

2 changes: 2 additions & 0 deletions c2rust-transpile/tests/snapshots/[email protected]
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
---
source: c2rust-transpile/tests/snapshots.rs
assertion_line: 67
expression: cat tests/snapshots/atomics.rs
input_file: c2rust-transpile/tests/snapshots/atomics.c
---
Expand Down Expand Up @@ -44,3 +45,4 @@ pub unsafe extern "C" fn c11_atomics(mut x: std::ffi::c_int) -> std::ffi::c_int
fresh1.1;
return x;
}

2 changes: 2 additions & 0 deletions c2rust-transpile/tests/snapshots/[email protected]
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
---
source: c2rust-transpile/tests/snapshots.rs
assertion_line: 67
expression: cat tests/snapshots/factorial.rs
input_file: c2rust-transpile/tests/snapshots/factorial.c
---
Expand All @@ -24,3 +25,4 @@ pub unsafe extern "C" fn factorial(mut n: std::ffi::c_ushort) -> std::ffi::c_ush
}
return result;
}

2 changes: 2 additions & 0 deletions c2rust-transpile/tests/snapshots/[email protected]
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
---
source: c2rust-transpile/tests/snapshots.rs
assertion_line: 67
expression: cat tests/snapshots/gotos.rs
input_file: c2rust-transpile/tests/snapshots/gotos.c
---
Expand All @@ -22,3 +23,4 @@ pub unsafe extern "C" fn sum(mut count: std::ffi::c_int) -> std::ffi::c_int {
}
return x;
}

2 changes: 2 additions & 0 deletions c2rust-transpile/tests/snapshots/[email protected]
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
---
source: c2rust-transpile/tests/snapshots.rs
assertion_line: 67
expression: cat tests/snapshots/insertion.rs
input_file: c2rust-transpile/tests/snapshots/insertion.c
---
Expand Down Expand Up @@ -30,3 +31,4 @@ pub unsafe extern "C" fn insertion_sort(n: std::ffi::c_int, p: *mut std::ffi::c_
i;
}
}

2 changes: 2 additions & 0 deletions c2rust-transpile/tests/snapshots/[email protected]
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
---
source: c2rust-transpile/tests/snapshots.rs
assertion_line: 67
expression: cat tests/snapshots/rotate.rs
input_file: c2rust-transpile/tests/snapshots/rotate.c
---
Expand Down Expand Up @@ -40,3 +41,4 @@ pub unsafe extern "C" fn rotate_right_16(
pub unsafe extern "C" fn rotate_right_32(mut x: std::ffi::c_uint) -> std::ffi::c_uint {
return x.rotate_right(3 as std::ffi::c_int as std::ffi::c_uint as u32);
}

2 changes: 2 additions & 0 deletions c2rust-transpile/tests/snapshots/[email protected]
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
---
source: c2rust-transpile/tests/snapshots.rs
assertion_line: 67
expression: cat tests/snapshots/spin.rs
input_file: c2rust-transpile/tests/snapshots/spin.c
---
Expand All @@ -16,3 +17,4 @@ input_file: c2rust-transpile/tests/snapshots/spin.c
pub unsafe extern "C" fn spin() {
::core::hint::spin_loop();
}