test: make sure fmt-write-bloat does not vacuously pass

Author: jieyouxu

tests/run-make/fmt-write-bloat/rmake.rs

@@ -12,24 +12,42 @@
 //! present.
 //!
 //! Some CI jobs try to run faster by disabling debug assertions (through setting
-//! `NO_DEBUG_ASSERTIONS=1`). If debug assertions are disabled, then we can check for the absence of
-//! additional `usize` formatting and padding related symbols.
+//! `NO_DEBUG_ASSERTIONS=1`). If std debug assertions are disabled, then we can check for the
+//! absence of additional `usize` formatting and padding related symbols.
 
 //@ ignore-cross-compile
 
-use run_make_support::artifact_names::bin_name;
+use std::path::Path;
+
 use run_make_support::env::std_debug_assertions_enabled;
-use run_make_support::rustc;
 use run_make_support::symbols::object_contains_any_symbol_substring;
+use run_make_support::{is_darwin, rustc};
+
+// Not applicable for `extern "C"` symbol decoration handling.
+fn sym(sym_name: &str) -> String {
+    if is_darwin() {
+        // Symbols are decorated with an underscore prefix on darwin platforms.
+        format!("_{sym_name}")
+    } else {
+        sym_name.to_string()
+    }
+}
 
 fn main() {
-    rustc().input("main.rs").opt().run();
     // panic machinery identifiers, these should not appear in the final binary
     let mut panic_syms = vec!["panic_bounds_check", "Debug"];
     if std_debug_assertions_enabled() {
         // if debug assertions are allowed, we need to allow these,
         // otherwise, add them to the list of symbols to deny.
         panic_syms.extend_from_slice(&["panicking", "panic_fmt", "pad_integral", "Display"]);
     }
-    assert!(!object_contains_any_symbol_substring(bin_name("main"), &panic_syms));
+    let panic_syms = panic_syms.into_iter().map(|name| sym(name)).collect::<Vec<_>>();
+
+    let expect_no_panic_symbols = Path::new("expect_no_panic_symbols");
+    rustc().input("main.rs").output(&expect_no_panic_symbols).opt().run();
+    assert!(!object_contains_any_symbol_substring(&expect_no_panic_symbols, &panic_syms));
+
+    let expect_panic_symbols = Path::new("expect_panic_symbols");
+    rustc().input("main.rs").output(&expect_panic_symbols).run();
+    assert!(object_contains_any_symbol_substring(&expect_panic_symbols, &panic_syms));
 }