Rollup merge of #127654 - nikic:llvm-ndebug-fix, r=cuviper

Fix incorrect NDEBUG handling in LLVM bindings

We currently compile our LLVM bindings using `-DNDEBUG` if debuginfo for LLVM is disabled. However, `NDEBUG` doesn't have any relation to debuginfo, it controls whether assertions are enabled.

Split the LLVM_NDEBUG environment variable into two, so that assertions and debuginfo are controlled independently.

After this change, `LLVMRustDIBuilderInsertDeclareAtEnd` triggers an assertion failure on LLVM 19 due to an incorrect cast. Fix it by removing the unused return value entirely.

r? `@cuviper`

Author: jhpratt

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -2057,7 +2057,7 @@ extern "C" {
         AddrOpsCount: c_uint,
         DL: &'a DILocation,
         InsertAtEnd: &'a BasicBlock,
-    ) -> &'a Value;
+    );
 
     pub fn LLVMRustDIBuilderCreateEnumerator<'a>(
         Builder: &DIBuilder<'a>,

compiler/rustc_llvm/build.rs

@@ -197,9 +197,8 @@ fn main() {
         cfg.define("LLVM_RUSTLLVM", None);
     }
 
-    if tracked_env_var_os("LLVM_NDEBUG").is_some() {
+    if tracked_env_var_os("LLVM_ASSERTIONS").is_none() {
         cfg.define("NDEBUG", None);
-        cfg.debug(false);
     }
 
     rerun_if_changed_anything_in_dir(Path::new("llvm-wrapper"));

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -1137,20 +1137,15 @@ LLVMRustDIBuilderGetOrCreateArray(LLVMRustDIBuilderRef Builder,
       Builder->getOrCreateArray(ArrayRef<Metadata *>(DataValue, Count)).get());
 }
 
-extern "C" LLVMValueRef LLVMRustDIBuilderInsertDeclareAtEnd(
+extern "C" void LLVMRustDIBuilderInsertDeclareAtEnd(
     LLVMRustDIBuilderRef Builder, LLVMValueRef V, LLVMMetadataRef VarInfo,
     uint64_t *AddrOps, unsigned AddrOpsCount, LLVMMetadataRef DL,
     LLVMBasicBlockRef InsertAtEnd) {
-  auto Result = Builder->insertDeclare(
-      unwrap(V), unwrap<DILocalVariable>(VarInfo),
-      Builder->createExpression(
-          llvm::ArrayRef<uint64_t>(AddrOps, AddrOpsCount)),
-      DebugLoc(cast<MDNode>(unwrap(DL))), unwrap(InsertAtEnd));
-#if LLVM_VERSION_GE(19, 0)
-  return wrap(Result.get<llvm::Instruction *>());
-#else
-  return wrap(Result);
-#endif
+  Builder->insertDeclare(unwrap(V), unwrap<DILocalVariable>(VarInfo),
+                         Builder->createExpression(
+                             llvm::ArrayRef<uint64_t>(AddrOps, AddrOpsCount)),
+                         DebugLoc(cast<MDNode>(unwrap(DL))),
+                         unwrap(InsertAtEnd));
 }
 
 extern "C" LLVMMetadataRef LLVMRustDIBuilderCreateEnumerator(

src/bootstrap/src/core/build_steps/compile.rs

@@ -1213,8 +1213,8 @@ fn rustc_llvm_env(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetSelect
     if builder.config.llvm_use_libcxx {
         cargo.env("LLVM_USE_LIBCXX", "1");
     }
-    if builder.config.llvm_optimize && !builder.config.llvm_release_debuginfo {
-        cargo.env("LLVM_NDEBUG", "1");
+    if builder.config.llvm_assertions {
+        cargo.env("LLVM_ASSERTIONS", "1");
     }
 }