Auto merge of #128147 - lolbinarycat:fmt-write-bloat-rmake, r=<try>

migrate fmt-write-bloat to rmake

try-job: aarch64-apple
try-job: x86_64-gnu-llvm-18
try-job: dist-x86_64-linux

src/tools/run-make-support/src/env.rs

@@ -17,3 +17,10 @@ pub fn env_var_os(name: &str) -> OsString {
         None => panic!("failed to retrieve environment variable {name:?}"),
     }
 }
+
+/// Check if `NO_DEBUG_ASSERTIONS` is set (usually this may be set in CI jobs).
+#[track_caller]
+#[must_use]
+pub fn no_debug_assertions() -> bool {
+    std::env::var_os("NO_DEBUG_ASSERTIONS").is_some()
+}

src/tools/run-make-support/src/lib.rs

@@ -21,6 +21,7 @@ pub mod run;
 pub mod scoped_run;
 pub mod string;
 pub mod targets;
+pub mod symbols;
 
 // Internally we call our fs-related support module as `fs`, but re-export its content as `rfs`
 // to tests to avoid colliding with commonly used `use std::fs;`.

src/tools/run-make-support/src/symbols.rs

@@ -0,0 +1,37 @@
+use object::{self, Object, ObjectSymbol, SymbolIterator};
+use std::fs;
+use std::path::Path;
+
+/// iterate through the symbols in an object file.
+///
+/// uses a callback because SymbolIterator does not own its data
+pub fn with_symbol_iter<P, F, R>(path: P, func: F) -> R
+where
+    P: AsRef<Path>,
+    //I: Iterator + 'a,
+    F: FnOnce(&mut SymbolIterator<'_, '_>) -> R,
+{
+    let raw_bytes = fs::read(path).expect("unable to read file");
+    let f = object::File::parse(raw_bytes.as_slice()).expect("unable to parse file");
+    let mut iter = f.symbols();
+    func(&mut iter)
+}
+
+pub fn any_symbol_contains(path: impl AsRef<Path>, substrings: &[&str]) -> bool {
+    with_symbol_iter(path, |syms| {
+        for sym in syms {
+            for substring in substrings {
+                if sym
+                    .name_bytes()
+                    .unwrap()
+                    .windows(substring.len())
+                    .any(|x| x == substring.as_bytes())
+                {
+                    eprintln!("{:?} contains {}", sym, substring);
+                    return true;
+                }
+            }
+        }
+        false
+    })
+}

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

@@ -0,0 +1,16 @@
+//@ ignore-windows
+//@ ignore-cross-compile
+
+use run_make_support::{env::no_debug_assertions, rustc, symbols::any_symbol_contains};
+
+fn main() {
+    rustc().input("main.rs").run();
+    // panic machinery identifiers, these should not appear in the final binary
+    let mut panic_syms = vec!["panic_bounds_check", "Debug"];
+    if no_debug_assertions() {
+        // 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!(!any_symbol_contains("main", &panic_syms));
+}