[lld] [NFC][ELF] Wrap invokeELFT in do { } while (0) so it behaves as a function (PR #150119)

[Jessica Clarke via llvm-commits]

https://github.com/jrtc27 created https://github.com/llvm/llvm-project/pull/150119

The current implementation is dangerous if used in contexts that need a
single statement, since invokeELFT(...); is in fact two statements, a
switch statement and an empty statement.


>From e64d09c4edc11bfeb67c1a8c4a4255f64bbbbb6e Mon Sep 17 00:00:00 2001
From: Jessica Clarke <jrtc27 at jrtc27.com>
Date: Tue, 22 Jul 2025 22:45:59 +0100
Subject: [PATCH] [NFC][ELF] Wrap invokeELFT in do { } while (0) so it behaves
 as a function

The current implementation is dangerous if used in contexts that need a
single statement, since invokeELFT(...); is in fact two statements, a
switch statement and an empty statement.
---
 lld/ELF/Target.h | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/lld/ELF/Target.h b/lld/ELF/Target.h
index 93f15920bfedb..fc20dae87584c 100644
--- a/lld/ELF/Target.h
+++ b/lld/ELF/Target.h
@@ -338,21 +338,23 @@ inline uint64_t overwriteULEB128(uint8_t *bufLoc, uint64_t val) {
 #pragma clang diagnostic ignored "-Wgnu-zero-variadic-macro-arguments"
 #endif
 #define invokeELFT(f, ...)                                                     \
-  switch (ctx.arg.ekind) {                                                     \
-  case lld::elf::ELF32LEKind:                                                  \
-    f<llvm::object::ELF32LE>(__VA_ARGS__);                                     \
-    break;                                                                     \
-  case lld::elf::ELF32BEKind:                                                  \
-    f<llvm::object::ELF32BE>(__VA_ARGS__);                                     \
-    break;                                                                     \
-  case lld::elf::ELF64LEKind:                                                  \
-    f<llvm::object::ELF64LE>(__VA_ARGS__);                                     \
-    break;                                                                     \
-  case lld::elf::ELF64BEKind:                                                  \
-    f<llvm::object::ELF64BE>(__VA_ARGS__);                                     \
-    break;                                                                     \
-  default:                                                                     \
-    llvm_unreachable("unknown ctx.arg.ekind");                                 \
-  }
+  do {                                                                         \
+      switch (ctx.arg.ekind) {                                                 \
+      case lld::elf::ELF32LEKind:                                              \
+        f<llvm::object::ELF32LE>(__VA_ARGS__);                                 \
+        break;                                                                 \
+      case lld::elf::ELF32BEKind:                                              \
+        f<llvm::object::ELF32BE>(__VA_ARGS__);                                 \
+        break;                                                                 \
+      case lld::elf::ELF64LEKind:                                              \
+        f<llvm::object::ELF64LE>(__VA_ARGS__);                                 \
+        break;                                                                 \
+      case lld::elf::ELF64BEKind:                                              \
+        f<llvm::object::ELF64BE>(__VA_ARGS__);                                 \
+        break;                                                                 \
+      default:                                                                 \
+        llvm_unreachable("unknown ctx.arg.ekind");                             \
+      }                                                                        \
+  } while (0)
 
 #endif