[lld] 9a1ca24 - [ELF] --warn-backrefs: --defsym does not make a backward reference

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2024-01-29T13:26:33-08:00
New Revision: 9a1ca245c8bc60b1ca12cd906fb31130801d977e

URL: https://github.com/llvm/llvm-project/commit/9a1ca245c8bc60b1ca12cd906fb31130801d977e
DIFF: https://github.com/llvm/llvm-project/commit/9a1ca245c8bc60b1ca12cd906fb31130801d977e.diff

LOG: [ELF] --warn-backrefs: --defsym does not make a backward reference

The interaction between --warn-backrefs was not tested, but if
--defsym-created reference causes archive member extraction, it seems
reasonable to suppress the diagnostic, which was the behavior before #78944.

Added: 
    

Modified: 
    lld/ELF/InputFiles.cpp
    lld/test/ELF/warn-backrefs.s

Removed: 
    


################################################################################
diff  --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index 75e5ee1d0da4f56..a292e873e72f71f 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -1788,7 +1788,12 @@ void BinaryFile::parse() {
 }
 
 InputFile *elf::createInternalFile(StringRef name) {
-  return make<InputFile>(InputFile::InternalKind, MemoryBufferRef("", name));
+  auto *file =
+      make<InputFile>(InputFile::InternalKind, MemoryBufferRef("", name));
+  // References from an internal file do not lead to --warn-backrefs
+  // diagnostics.
+  file->groupId = 0;
+  return file;
 }
 
 ELFFileBase *elf::createObjFile(MemoryBufferRef mb, StringRef archiveName,

diff  --git a/lld/test/ELF/warn-backrefs.s b/lld/test/ELF/warn-backrefs.s
index 1e5c14ed052e66a..453017eb1c8ec35 100644
--- a/lld/test/ELF/warn-backrefs.s
+++ b/lld/test/ELF/warn-backrefs.s
@@ -100,6 +100,10 @@
 ## -u does not make a backward reference.
 # RUN: ld.lld --fatal-warnings --warn-backrefs -u foo %t2.a %t1.o -o /dev/null
 
+## --defsym does not make a backward reference, but it does not suppress the warning due to another file.
+# RUN: ld.lld --fatal-warnings --warn-backrefs --defsym=x=foo -e 0 %t2.a -o /dev/null
+# RUN: ld.lld --warn-backrefs --defsym=x=foo %t2.a %t1.o -o /dev/null 2>&1 | FileCheck %s
+
 # RUN: not ld.lld --warn-backrefs-exclude='[' 2>&1 | FileCheck --check-prefix=INVALID %s
 # INVALID: error: --warn-backrefs-exclude: invalid glob pattern, unmatched '[': [