Use pdb to read PDB symbols in fmt-write-bloat

As trying to read `main.exe` itself will yield no symbols.

Author: jieyouxu

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

@@ -17,10 +17,9 @@
 
 //@ 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_msvc, pdb, rustc, target};
 
 fn main() {
     rustc().input("main.rs").opt().run();
@@ -31,8 +30,40 @@ fn main() {
         // otherwise, add them to the list of symbols to deny.
         panic_syms.extend_from_slice(&["panicking", "panic_fmt", "pad_integral", "Display"]);
     }
-    // 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));
+
+    if is_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.
+        assert!(found_symbols.iter().any(|sym| sym == "main"), "expected `main` symbol");
+
+        for found_symbol in found_symbols {
+            for panic_symbol in &panic_syms {
+                assert_ne!(found_symbol, *panic_symbol, "found unexpected panic machinery symbol");
+            }
+        }
+    } else {
+        // 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));
+    }
 }