[ELF] Increase NextGroupId with --end-group

[ruiu]

I think you need to fix readGroup in ScriptParser.cpp as well.

[MaskRay]

Fix readGroup as well

[ruiu]

Please add a test for the linker script.

ELF/ScriptParser.cpp

336

I think you should do this only when Orig is false. Consider a scenario like this

ld.lld -( a.o b.script c.o -)

where b.script contains "GROUP(d.o e.o)". All these object files (i.e. a.o c.o d.o and e.o) should be in the same group, so we don't want to increment NextGroupId at end of the GROUP directive.

[MaskRay]

Add test for GROUP()

[ruiu]

LGTM

[MaskRay]

Add Rui's nested -( t3.script t1.o -) test

ELF/Driver.cpp

case OPT_start_group:
       if (InputFile::IsInGroup)
         error("nested --start-group");
       InputFile::IsInGroup = true;
       break;
     case OPT_end_group:
       if (!InputFile::IsInGroup)
         error("stray --end-group");
       InputFile::IsInGroup = false;
+      ++InputFile::NextGroupId;
       break;
     case OPT_start_lib:
       InLib = true;
       break;
     case OPT_end_lib:
       InLib = false;
       break;
     }

ELF/InputFiles.h

public:
   bool JustSymbols = false;
 
   // GroupId is used for --warn-backrefs which is an optional error
   // checking feature. All files within the same --{start,end}-group
   // get the same group ID. Otherwise, each file gets a new group
   // ID. For more info, see checkDependency() in SymbolTable.cpp.
   uint32_t GroupId;
   static bool IsInGroup;
+  static uint32_t NextGroupId;
 
 protected:
   InputFile(Kind K, MemoryBufferRef M);
   std::vector<InputSectionBase *> Sections;
   std::vector<Symbol *> Symbols;
 
 private:
   const Kind FileKind;
-
-  static uint32_t NextGroupId;
 };
 
 template <typename ELFT> class ELFFileBase : public InputFile {
 public:
   typedef typename ELFT::Shdr Elf_Shdr;
   typedef typename ELFT::Sym Elf_Sym;
   typedef typename ELFT::Word Elf_Word;
   typedef typename ELFT::SymRange Elf_Sym_Range;

ELF/ScriptParser.cpp

while (!errorCount() && !consume(")"))
     Config->Undefined.push_back(next());
 }
 
 void ScriptParser::readGroup() {
   bool Orig = InputFile::IsInGroup;
   InputFile::IsInGroup = true;
   readInput();
   InputFile::IsInGroup = Orig;
+  if (!Orig)
+    ++InputFile::NextGroupId;
 }
 
 void ScriptParser::readInclude() {
   StringRef Tok = unquote(next());
 
   if (!Seen.insert(Tok).second) {
     setError("there is a cycle in linker script INCLUDEs");
     return;

test/ELF/warn-backrefs.s

 # RUN: echo "INPUT(\"%t1.o\" \"%t2.a\")" > %t1.script
 # RUN: ld.lld --fatal-warnings --warn-backrefs -o %t.exe %t1.script
 
 # RUN: echo "GROUP(\"%t2.a\" \"%t1.o\")" > %t2.script
 # RUN: ld.lld --fatal-warnings --warn-backrefs -o %t.exe %t2.script
 
 # RUN: not ld.lld --fatal-warnings --warn-backrefs -o %t.exe %t2.a %t1.o 2>&1 | FileCheck %s
 # RUN: not ld.lld --fatal-warnings --warn-backrefs -o %t.exe %t2.a "-(" %t1.o "-)" 2>&1 | FileCheck %s
+# RUN: not ld.lld --fatal-warnings --warn-backrefs -o %t.exe --start-group %t2.a --end-group %t1.o 2>&1 | FileCheck %s
+
+# RUN: echo "GROUP(\"%t2.a\")" > %t3.script
+# RUN: not ld.lld --fatal-warnings --warn-backrefs -o %t.exe %t3.script %t1.o 2>&1 | FileCheck %s
 
 # CHECK: backward reference detected: foo in {{.*}}1.o refers to {{.*}}2.a
 
 # RUN: not ld.lld --fatal-warnings --start-group --start-group 2>&1 | FileCheck -check-prefix=START %s
 # START: nested --start-group
 
 # RUN: not ld.lld --fatal-warnings --end-group 2>&1 | FileCheck -check-prefix=END %s
 # END: stray --end-group
 
 .globl _start, foo
 _start:
   call foo