Stop mangling rust_eh_personality again for now

Some projects manually define rust_eh_personality as they use no_std on
a target where libcore is compiled with panic=unwind and thus need
rust_eh_personality to be present while it is only defined in libstd.
These projects don't want to use unstable features and thus can't use a
proper #[lang = "eh_personality"].

Author: bjorn3

compiler/rustc_symbol_mangling/src/v0.rs

@@ -132,6 +132,13 @@ pub fn eh_personality_symbol<'tcx>(tcx: TyCtxt<'tcx>) -> String {
 
 pub fn mangle_internal_symbol<'tcx>(tcx: TyCtxt<'tcx>, item_name: &str) -> String {
     match item_name {
+        // Some projects manually define rust_eh_personality as they use no_std on a target where
+        // libcore is compiled with panic=unwind and thus need rust_eh_personality to be present
+        // while it is only defined in libstd. These projects don't want to use unstable features
+        // and thus can't use a proper #[lang = "eh_personality"]
+        // FIXME mangle again once no_std on a target with std support doesn't need it or build-std
+        // is possible on stable for non-Cargo build systems.
+        "rust_eh_personality" => return item_name.to_owned(),
         // Apple availability symbols need to not be mangled to be usable by
         // C/Objective-C code.
         "__isPlatformVersionAtLeast" | "__isOSVersionAtLeast" => return item_name.to_owned(),

tests/run-make/symbols-all-mangled/rmake.rs

@@ -34,6 +34,10 @@ fn is_symbol_ok(sym: &str) -> bool {
         return true;
     }
 
+    if sym == "rust_eh_personality" {
+        return true; // Unfortunately we have to not mangle this for now
+    }
+
     false
 }
 

tests/ui/sanitizer/dataflow-abilist.txt

@@ -494,4 +494,5 @@ fun:_ZN4core*=uninstrumented
 fun:_R*4core*=uninstrumented
 fun:_ZN3std*=uninstrumented
 fun:_R*3std*=uninstrumented
+fun:rust_eh_personality=uninstrumented
 fun:_R*__rustc*=uninstrumented