coverage: Don't convert symbol names to CString for FFI

compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs

@@ -25,7 +25,6 @@ use rustc_middle::ty::Instance;
 use rustc_middle::ty::Ty;
 
 use std::cell::RefCell;
-use std::ffi::CString;
 
 pub(crate) mod ffi;
 pub(crate) mod map_data;
@@ -332,10 +331,15 @@ fn create_pgo_func_name_var<'ll, 'tcx>(
     cx: &CodegenCx<'ll, 'tcx>,
     instance: Instance<'tcx>,
 ) -> &'ll llvm::Value {
-    let mangled_fn_name = CString::new(cx.tcx.symbol_name(instance).name)
-        .expect("error converting function name to C string");
+    let mangled_fn_name: &str = cx.tcx.symbol_name(instance).name;
     let llfn = cx.get_fn(instance);
-    unsafe { llvm::LLVMRustCoverageCreatePGOFuncNameVar(llfn, mangled_fn_name.as_ptr()) }
+    unsafe {
+        llvm::LLVMRustCoverageCreatePGOFuncNameVar(
+            llfn,
+            mangled_fn_name.as_ptr().cast(),
+            mangled_fn_name.len(),
+        )
+    }
 }
 
 pub(crate) fn write_filenames_section_to_buffer<'a>(