[lld] COFF: Improve undefined symbol diagnostics.

[pcc]

Summary

We now report the names of any files containing undefined symbol references.

[ruiu]

LGTM with nits.

COFF/SymbolTable.cpp

159

Inverse this condition and return early.

163

Use actual type instead of auto.

COFF/SymbolTable.cpp

std::error_code SymbolTable::readObjects() {
   return std::error_code();
 }
 
 bool SymbolTable::queueEmpty() {
   return ArchiveQueue.empty() && ObjectQueue.empty();
 }
 
 bool SymbolTable::reportRemainingUndefines(bool Resolve) {
-  bool Ret = false;
+  llvm::SmallPtrSet<SymbolBody *, 8> Undefs;
   for (auto &I : Symtab) {
     Symbol *Sym = I.second;
     auto *Undef = dyn_cast<Undefined>(Sym->Body);
     if (!Undef)
       continue;
     StringRef Name = Undef->getName();
     // A weak alias may have been resolved, so check for that.
     if (Defined *D = Undef->getWeakAlias()) {
if (Name.startswith("__imp_")) {
           continue;
         auto *D = cast<Defined>(Imp->Body);
         auto *S = new (Alloc) DefinedLocalImport(Name, D);
         LocalImportChunks.push_back(S->getChunk());
         Sym->Body = S;
         continue;
       }
     }
-    llvm::errs() << "undefined symbol: " << Name << "\n";
     // Remaining undefined symbols are not fatal if /force is specified.
     // They are replaced with dummy defined symbols.
-    if (Config->Force) {
-      if (Resolve)
-        Sym->Body = new (Alloc) DefinedAbsolute(Name, 0);
-      continue;
-    }
-    Ret = true;
+    if (Config->Force && Resolve)
+    Undefs.insert(Sym->Body);
+  if (!Undefs.empty()) {
+    for (Undefined *U : Config->GCRoot)
+      if (Undefs.count(U->repl()))
+        llvm::errs() << "<root>: undefined symbol: " << U->getName() << "\n";
+    for (auto &File : Files)
+      if (!isa<ArchiveFile>(File.get()))
+        for (SymbolBody *Sym : File->getSymbols())
+          if (Undefs.count(Sym->repl()))
+            llvm::errs() << File->getShortName() << ": undefined symbol: "
+                         << Sym->getName() << "\n";
+    return !Config->Force;
   }
-  return Ret;
+  return false;
 }
 
 void SymbolTable::addLazy(Lazy *New, std::vector<Symbol *> *Accum) {
   Symbol *Sym = insert(New);
   if (Sym->Body == New)
     return;
   for (;;) {
     SymbolBody *Existing = Sym->Body;

test/COFF/entry-inference.test

 # RUN: sed -e s/ENTRYNAME/main/ %s | yaml2obj > %t.obj
 # RUN: not lld -flavor link2 /out:%t.exe %t.obj > %t.log 2>&1
 # RUN: FileCheck -check-prefix=MAIN %s < %t.log
 
 # RUN: sed s/ENTRYNAME/wmain/ %s | yaml2obj > %t.obj
 # RUN: not lld -flavor link2 /out:%t.exe %t.obj > %t.log 2>&1
 # RUN: FileCheck -check-prefix=WMAIN %s < %t.log
 
 # RUN: sed s/ENTRYNAME/WinMain/ %s | yaml2obj > %t.obj
 # RUN: not lld -flavor link2 /out:%t.exe %t.obj > %t.log 2>&1
 # RUN: FileCheck -check-prefix=WINMAIN %s < %t.log
 
 # RUN: sed s/ENTRYNAME/wWinMain/ %s | yaml2obj > %t.obj
 # RUN: not lld -flavor link2 /out:%t.exe %t.obj > %t.log 2>&1
 # RUN: FileCheck -check-prefix=WWINMAIN %s < %t.log
 
-# MAIN:     undefined symbol: mainCRTStartup
-# WMAIN:    undefined symbol: wmainCRTStartup
-# WINMAIN:  undefined symbol: WinMainCRTStartup
-# WWINMAIN: undefined symbol: wWinMainCRTStartup
+# MAIN:     <root>: undefined symbol: mainCRTStartup
+# WMAIN:    <root>: undefined symbol: wmainCRTStartup
+# WINMAIN:  <root>: undefined symbol: WinMainCRTStartup
+# WWINMAIN: <root>: undefined symbol: wWinMainCRTStartup
 
 ---
 header:
   Machine:         IMAGE_FILE_MACHINE_AMD64
   Characteristics: []
 sections:
   - Name:            .text
     Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]

test/COFF/force.test

 # RUN: yaml2obj < %s > %t.obj
 # RUN: not lld -flavor link2 /out:%t.exe /entry:main %t.obj >& %t.log
 # RUN: FileCheck %s < %t.log
 # RUN: lld -flavor link2 /out:%t.exe /entry:main %t.obj /force >& %t.log
 # RUN: FileCheck %s < %t.log
 
-# CHECK: undefined symbol: foo
+# CHECK: .obj: undefined symbol: foo
 
 ---
 header:
   Machine:         IMAGE_FILE_MACHINE_AMD64
   Characteristics: []
 sections:
   - Name:            .text
     Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]

test/COFF/nodefaultlib.test

 
 # RUN: lld -flavor link2 /libpath:%T /out:%t.exe /entry:main \
 # RUN:   /subsystem:console hello64.obj /defaultlib:std64 \
 # RUN:   /nodefaultlib:std64.lib >& %t.log || true
 # RUN: FileCheck -check-prefix=CHECK3 %s < %t.log
 
 CHECK1: hello64.obj: {{[Nn]}}o such file or directory
 CHECK2: hello64: {{[Nn]}}o such file or directory
-CHECK3: undefined symbol: MessageBoxA
+CHECK3: hello64.obj: undefined symbol: MessageBoxA
 
 # RUN: lld -flavor link2 /libpath:%T /out:%t.exe /entry:main \
 # RUN:   /subsystem:console hello64.obj /defaultlib:std64.lib
 
 # RUN: env LIB=%T lld -flavor link2 /out:%t.exe /entry:main \
 # RUN:   /subsystem:console hello64.obj /defaultlib:std64.lib