lld-link: Separate 'undefined symbol' errors with just one newline, not two.

[thakis]

Summary

newline() in ErrorHandler.cpp already tries to insert newlines between messages that contain embedded newlines, so getSymbolLocations() shouldn't return a string that ends in a newline -- else we end up with two newlines between error messages.

Makes lld-link's output look more like ld.lld output.
Before:

lld-link: error: undefined symbol: _f
>>> referenced by /Users/thakis/src/llvm-mono/test.c:4
>>>               test.obj:(_main)


lld-link: error: undefined symbol: _g
>>> referenced by /Users/thakis/src/llvm-mono/test.c:4
>>>               test.obj:(_main)


lld-link: error: undefined symbol: _h
>>> referenced by /Users/thakis/src/llvm-mono/test.c:4
>>>               test.obj:(_main)

After:

lld-link: error: undefined symbol: _f
>>> referenced by /Users/thakis/src/llvm-mono/test.c:4
>>>               test.obj:(_main)

lld-link: error: undefined symbol: _g
>>> referenced by /Users/thakis/src/llvm-mono/test.c:4
>>>               test.obj:(_main)

lld-link: error: undefined symbol: _h
>>> referenced by /Users/thakis/src/llvm-mono/test.c:4
>>>               test.obj:(_main)

[pcc]

LGTM

[thakis]

r340482, thanks!

lld/COFF/SymbolTable.cpp

for (const coff_relocation &R : SC->Relocs) {
           getFileLine(SC, R.VirtualAddress);
       StringRef SymName = getSymbolName(SC, R.VirtualAddress);
       if (!FileLine.first.empty() || !SymName.empty())
         Locations.push_back({SymName, FileLine});
     }
   }
 
   if (Locations.empty())
-    return "\n>>> referenced by " + toString(File) + "\n";
+    return "\n>>> referenced by " + toString(File);
 
   std::string Out;
   llvm::raw_string_ostream OS(Out);
   for (Location Loc : Locations) {
     OS << "\n>>> referenced by ";
     if (!Loc.FileLine.first.empty())
       OS << Loc.FileLine.first << ":" << Loc.FileLine.second
          << "\n>>>               ";
     OS << toString(File);
     if (!Loc.SymName.empty())
       OS << ":(" << Loc.SymName << ')';
   }
-  OS << '\n';
   return OS.str();
 }
 
 void SymbolTable::reportRemainingUndefines() {
   SmallPtrSet<Symbol *, 8> Undefs;
   DenseMap<Symbol *, Symbol *> LocalImports;
 
   for (auto &I : SymMap) {

lld/test/COFF/undefined-symbol-cv.s

 # REQUIRES: x86
 # RUN: llvm-mc -triple=x86_64-windows-msvc -filetype=obj -o %t.obj %s
 # RUN: not lld-link /out:%t.exe %t.obj 2>&1 | FileCheck %s
 
 # CHECK: error: undefined symbol: ?foo@@YAHXZ
 # CHECK-NEXT: >>> referenced by file1.cpp:1
 # CHECK-NEXT: >>>               {{.*}}.obj:(main)
 # CHECK-NEXT: >>> referenced by file1.cpp:2
 # CHECK-NEXT: >>>               {{.*}}.obj:(main)
-
-# CHECK: error: undefined symbol: ?bar@@YAHXZ
+# CHECK-EMPTY:
+# CHECK-NEXT: error: undefined symbol: ?bar@@YAHXZ
 # CHECK-NEXT: >>> referenced by file2.cpp:3
 # CHECK-NEXT: >>>               {{.*}}.obj:(main)
 # CHECK-NEXT: >>> referenced by file1.cpp:4
 # CHECK-NEXT: >>>               {{.*}}.obj:(f1)
-
-# CHECK: error: undefined symbol: ?baz@@YAHXZ
+# CHECK-EMPTY:
+# CHECK-NEXT: error: undefined symbol: ?baz@@YAHXZ
 # CHECK-NEXT: >>> referenced by file1.cpp:5
 # CHECK-NEXT: >>>               {{.*}}.obj:(f2)
 
   .cv_file  1 "file1.cpp" "EDA15C78BB573E49E685D8549286F33C" 1
   .cv_file  2 "file2.cpp" "EDA15C78BB573E49E685D8549286F33D" 1
 
         .section        .text,"xr",one_only,main
 .globl main

lld/test/COFF/undefined-symbol.s

 # REQUIRES: x86
 # RUN: llvm-mc -triple=x86_64-windows-msvc -filetype=obj -o %t.obj %s
 # RUN: not lld-link /out:%t.exe %t.obj 2>&1 | FileCheck %s
 
 # CHECK: error: undefined symbol: ?foo@@YAHXZ
 # CHECK-NEXT: >>> referenced by {{.*}}.obj:(main)
 # CHECK-NEXT: >>> referenced by {{.*}}.obj:(main)
-
-# CHECK: error: undefined symbol: ?bar@@YAHXZ
+# CHECK-EMPTY:
+# CHECK-NEXT: error: undefined symbol: ?bar@@YAHXZ
 # CHECK-NEXT: >>> referenced by {{.*}}.obj:(main)
 # CHECK-NEXT: >>> referenced by {{.*}}.obj:(f1)
-
-# CHECK: error: undefined symbol: ?baz@@YAHXZ
+# CHECK-EMPTY:
+# CHECK-NEXT: error: undefined symbol: ?baz@@YAHXZ
 # CHECK-NEXT: >>> referenced by {{.*}}.obj:(f2)
 
         .section        .text,"xr",one_only,main
 .globl main
 main:
   call  "?foo@@YAHXZ"
   call  "?foo@@YAHXZ"
   call  "?bar@@YAHXZ"