Auto merge of #143669 - jieyouxu:fmt-write-bloat, r=<try>

[WIP] Make sure `fmt-write-bloat` doesn't vacuously pass on no symbols

Previously, the test only checks for the absence of certain panic symbols, but having no symbols was also a possible albeit vacuous way to satisfy this assertion.

Fix this by checking we at least observe the `main` symbol which is always expected to be present.

Noticed in #142841 (comment).

r? `@ChrisDenton`

try-job: aarch64-apple
try-job: x86_64-apple-1
try-job: x86_64-msvc-1
try-job: i686-msvc-1
try-job: x86_64-mingw-1

Author: rust-bors[bot]

Cargo.lock

@@ -1196,6 +1196,12 @@ dependencies = [
  "once_cell",
 ]
 
+[[package]]
+name = "fallible-iterator"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4443176a9f2c162692bd3d352d745ef9413eec5782a80d8fd6f8a1ac692a07f7"
+
 [[package]]
 name = "fallible-iterator"
 version = "0.3.0"
@@ -1478,7 +1484,7 @@ version = "0.31.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "07e28edb80900c19c28f1072f2e8aeca7fa06b23cd4169cefe1af5aa3260783f"
 dependencies = [
- "fallible-iterator",
+ "fallible-iterator 0.3.0",
  "indexmap",
  "stable_deref_trait",
 ]
@@ -1489,7 +1495,7 @@ version = "0.32.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "93563d740bc9ef04104f9ed6f86f1e3275c2cdafb95664e26584b9ca807a8ffe"
 dependencies = [
- "fallible-iterator",
+ "fallible-iterator 0.3.0",
  "indexmap",
  "stable_deref_trait",
 ]
@@ -2765,6 +2771,17 @@ version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "df94ce210e5bc13cb6651479fa48d14f601d9858cfe0467f43ae157023b938d3"
 
+[[package]]
+name = "pdb"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "82040a392923abe6279c00ab4aff62d5250d1c8555dc780e4b02783a7aa74863"
+dependencies = [
+ "fallible-iterator 0.2.0",
+ "scroll",
+ "uuid",
+]
+
 [[package]]
 name = "percent-encoding"
 version = "2.3.1"
@@ -3221,6 +3238,7 @@ dependencies = [
  "gimli 0.32.0",
  "libc",
  "object 0.37.1",
+ "pdb",
  "regex",
  "serde_json",
  "similar",
@@ -4930,6 +4948,12 @@ version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
 
+[[package]]
+name = "scroll"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "04c565b551bafbef4157586fa379538366e4385d42082f255bfd96e4fe8519da"
+
 [[package]]
 name = "self_cell"
 version = "1.2.0"

src/tools/run-make-support/Cargo.toml

@@ -13,6 +13,7 @@ gimli = "0.32"
 build_helper = { path = "../../build_helper" }
 serde_json = "1.0"
 libc = "0.2"
+pdb = "0.8.0"
 
 [lib]
 crate-type = ["lib", "dylib"]

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

@@ -41,6 +41,7 @@ pub use bstr;
 pub use gimli;
 pub use libc;
 pub use object;
+pub use pdb;
 pub use regex;
 pub use serde_json;
 pub use similar;

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

@@ -15,21 +15,89 @@
 //! `NO_DEBUG_ASSERTIONS=1`). If debug assertions are disabled, then we can check for the absence of
 //! additional `usize` formatting and padding related symbols.
 
+// ignore-tidy-linelength
+
 //@ ignore-cross-compile
 
-use run_make_support::artifact_names::bin_name;
 use run_make_support::env::no_debug_assertions;
-use run_make_support::rustc;
 use run_make_support::symbols::any_symbol_contains;
+use run_make_support::{bin_name, is_darwin, is_windows_msvc, pdb, rustc, target};
+
+// 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"];
+    let mut panic_syms = vec![sym("panic_bounds_check"), sym("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"]);
+        panic_syms.extend_from_slice(&[
+            sym("panicking"),
+            sym("panic_fmt"),
+            sym("pad_integral"),
+            sym("Display"),
+        ]);
+    }
+
+    if is_windows_msvc() {
+        use pdb::FallibleIterator;
+
+        let file = std::fs::File::open("main.pdb").expect("failed to open `main.pdb`");
+        let mut pdb = pdb::PDB::open(file).expect("failed to parse `main.pdb`");
+
+        let symbol_table = pdb.global_symbols().expect("failed to parse PDB global symbols");
+        let mut symbols = symbol_table.iter();
+
+        let mut found_symbols = vec![];
+
+        while let Some(symbol) = symbols.next().expect("failed to parse symbol") {
+            match symbol.parse() {
+                Ok(pdb::SymbolData::Public(data)) => {
+                    found_symbols.push(data.name.to_string());
+                }
+                _ => {}
+            }
+        }
+
+        // Make sure we at least have the `main` symbol itself, otherwise even no symbols can
+        // trivially satisfy the "no panic symbol" assertion.
+        let main_sym = if is_darwin() {
+            // Symbols are decorated with an underscore prefix on darwin platforms.
+            "_main"
+        } else if target().contains("i686") && is_windows_msvc() {
+            // `extern "C"` i.e. `__cdecl` on `i686` windows-msvc means that the symbol will be
+            // decorated with an underscore, but not on `x86_64` windows-msvc.
+            // See <https://learn.microsoft.com/en-us/cpp/build/reference/decorated-names?view=msvc-170#FormatC>.
+            "_main"
+        } else {
+            "main"
+        };
+
+        assert!(found_symbols.iter().any(|sym| sym == main_sym), "expected `main` symbol");
+
+        for found_symbol in found_symbols {
+            for panic_symbol in &panic_syms {
+                assert_ne!(
+                    found_symbol,
+                    panic_symbol.as_str(),
+                    "found unexpected panic machinery symbol"
+                );
+            }
+        }
+    } else {
+        let panic_syms = panic_syms.iter().map(String::as_str).collect::<Vec<_>>();
+        // Make sure we at least have the `main` symbol itself, otherwise even no symbols can
+        // trivially satisfy the "no panic symbol" assertion.
+        assert!(any_symbol_contains(bin_name("main"), &["main"]));
+        assert!(!any_symbol_contains(bin_name("main"), &panic_syms));
     }
-    assert!(!any_symbol_contains(bin_name("main"), &panic_syms));
 }