transpile: snapshot: allow platform-dependent snapshots

we need to support different output on different platforms due to various
differences that we can't paper over. for example, macOS defines some builtins
with different types than Linux, and macOS libc and glibc have different typedef
setups for fixed-size types, resulting in different type alias preambles.

support these by appending the operating system to the snapshot name for
results that may vary by platform.

Author: fw-immunant

c2rust-transpile/tests/snapshots.rs

@@ -46,22 +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)
@@ -76,7 +61,12 @@ 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", "-o", "-"])
@@ -87,9 +77,21 @@ fn transpile(c_path: &Path) {
 
 #[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));
+    });
 }

c2rust-transpile/tests/snapshots/linux/rotate.c renamed to c2rust-transpile/tests/snapshots/platform-specific/rotate.c

@@ -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,
@@ -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;
 }
+

c2rust-transpile/tests/snapshots/linux/rotate.rs renamed to c2rust-transpile/tests/snapshots/platform-specific/rotate.rs

@@ -0,0 +1,28 @@
+---
+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);
+}
+

c2rust-transpile/tests/snapshots/snapshots__transpile@linux__rotate.c.snap renamed to c2rust-transpile/tests/snapshots/[email protected]

@@ -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
 ---
@@ -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;
 }
+

c2rust-transpile/tests/snapshots/[email protected]

@@ -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
 ---
@@ -24,3 +25,4 @@ pub unsafe extern "C" fn factorial(mut n: std::ffi::c_ushort) -> std::ffi::c_ush
     }
     return result;
 }
+

c2rust-transpile/tests/snapshots/[email protected]

@@ -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
 ---
@@ -22,3 +23,4 @@ pub unsafe extern "C" fn sum(mut count: std::ffi::c_int) -> std::ffi::c_int {
     }
     return x;
 }
+

c2rust-transpile/tests/snapshots/[email protected]

@@ -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
 ---
@@ -30,3 +31,4 @@ pub unsafe extern "C" fn insertion_sort(n: std::ffi::c_int, p: *mut std::ffi::c_
         i;
     }
 }
+

c2rust-transpile/tests/snapshots/[email protected]

@@ -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
 ---
@@ -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);
 }
+