llvm: Ignore error value that is always false

See llvm/llvm-project#121851

For LLVM 20+, this function (`renameModuleForThinLTO`) has no return
value. For prior versions of LLVM, this never failed, but had a
signature which allowed an error value people were handling.

Author: maurer

compiler/rustc_codegen_gcc/src/back/lto.rs

@@ -660,9 +660,7 @@ pub unsafe fn optimize_thin_module(
         {
             let _timer =
                 cgcx.prof.generic_activity_with_arg("LLVM_thin_lto_rename", thin_module.name());
-            if !llvm::LLVMRustPrepareThinLTORename(thin_module.shared.data.0, llmod, target) {
-                return Err(write::llvm_err(&dcx, LlvmError::PrepareThinLtoModule));
-            }
+            unsafe { llvm::LLVMRustPrepareThinLTORename(thin_module.shared.data.0, llmod, target) };
             save_temp_bitcode(cgcx, &module, "thin-lto-after-rename");
         }
 

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -730,11 +730,7 @@ pub(crate) unsafe fn optimize_thin_module(
         {
             let _timer =
                 cgcx.prof.generic_activity_with_arg("LLVM_thin_lto_rename", thin_module.name());
-            if unsafe {
-                !llvm::LLVMRustPrepareThinLTORename(thin_module.shared.data.0, llmod, target)
-            } {
-                return Err(write::llvm_err(dcx, LlvmError::PrepareThinLtoModule));
-            }
+            unsafe { llvm::LLVMRustPrepareThinLTORename(thin_module.shared.data.0, llmod, target) };
             save_temp_bitcode(cgcx, &module, "thin-lto-after-rename");
         }
 

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -2387,7 +2387,7 @@ unsafe extern "C" {
         Data: &ThinLTOData,
         Module: &Module,
         Target: &TargetMachine,
-    ) -> bool;
+    );
     pub fn LLVMRustPrepareThinLTOResolveWeak(Data: &ThinLTOData, Module: &Module) -> bool;
     pub fn LLVMRustPrepareThinLTOInternalize(Data: &ThinLTOData, Module: &Module) -> bool;
     pub fn LLVMRustPrepareThinLTOImport(

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -1373,20 +1373,14 @@ static bool clearDSOLocalOnDeclarations(Module &Mod, TargetMachine &TM) {
   return ClearDSOLocalOnDeclarations;
 }
 
-extern "C" bool LLVMRustPrepareThinLTORename(const LLVMRustThinLTOData *Data,
+extern "C" void LLVMRustPrepareThinLTORename(const LLVMRustThinLTOData *Data,
                                              LLVMModuleRef M,
                                              LLVMTargetMachineRef TM) {
   Module &Mod = *unwrap(M);
   TargetMachine &Target = *unwrap(TM);
 
   bool ClearDSOLocal = clearDSOLocalOnDeclarations(Mod, Target);
-  bool error = renameModuleForThinLTO(Mod, Data->Index, ClearDSOLocal);
-
-  if (error) {
-    LLVMRustSetLastError("renameModuleForThinLTO failed");
-    return false;
-  }
-  return true;
+  renameModuleForThinLTO(Mod, Data->Index, ClearDSOLocal);
 }
 
 extern "C" bool