Fix error messages for bad symbols.

[ruiu]

Summary

Previously, the error messages didn't contain symbol name because we
didn't read a symbol name for these error messages.

[pcc]

LGTM

lld/trunk/COFF/InputFiles.cpp

Symbol *ObjFile::createUndefined(COFFSymbolRef Sym) {
   StringRef Name;
   COFFObj->getSymbolName(Sym, Name);
   return Symtab->addUndefined(Name, this, Sym.isWeakExternal());
 }
 
 Optional<Symbol *> ObjFile::createDefined(
     COFFSymbolRef Sym,
     std::vector<const coff_aux_section_definition *> &ComdatDefs) {
-  StringRef Name;
+  auto GetName = [&]() {
+    StringRef S;
+    COFFObj->getSymbolName(Sym, S);
+    return S;
+  };
+
   if (Sym.isCommon()) {
     auto *C = make<CommonChunk>(Sym);
     Chunks.push_back(C);
-    COFFObj->getSymbolName(Sym, Name);
-    Symbol *S =
-        Symtab->addCommon(this, Name, Sym.getValue(), Sym.getGeneric(), C);
-    return S;
+    return Symtab->addCommon(this, GetName(), Sym.getValue(), Sym.getGeneric(),
+                             C);
   }
+
   if (Sym.isAbsolute()) {
-    COFFObj->getSymbolName(Sym, Name);
+    StringRef Name = GetName();
+
     // Skip special symbols.
     if (Name == "@comp.id")
       return nullptr;
     if (Name == "@feat.00") {
       Feat00Flags = Sym.getValue();
       return nullptr;
     }
+
     if (Sym.isExternal())
       return Symtab->addAbsolute(Name, Sym);
-    else
-      return make<DefinedAbsolute>(Name, Sym);
   }
+
   int32_t SectionNumber = Sym.getSectionNumber();
   if (SectionNumber == llvm::COFF::IMAGE_SYM_DEBUG)
     return nullptr;
 
   if (llvm::COFF::isReservedSectionNumber(SectionNumber))
-    fatal(toString(this) + ": " + Name +
+    fatal(toString(this) + ": " + GetName() +
           " should not refer to special section " + Twine(SectionNumber));
 
   if ((uint32_t)SectionNumber >= SparseChunks.size())
-    fatal(toString(this) + ": " + Name +
+    fatal(toString(this) + ": " + GetName() +
           " should not refer to non-existent section " + Twine(SectionNumber));
 
   // Handle comdat leader symbols.
   if (const coff_aux_section_definition *Def = ComdatDefs[SectionNumber]) {
     ComdatDefs[SectionNumber] = nullptr;
     Symbol *Leader;
     bool Prevailing;
     if (Sym.isExternal()) {
-      COFFObj->getSymbolName(Sym, Name);
       std::tie(Leader, Prevailing) =
-          Symtab->addComdat(this, Name, Sym.getGeneric());
+          Symtab->addComdat(this, GetName(), Sym.getGeneric());
     } else {
       Leader = make<DefinedRegular>(this, /*Name*/ "", false,
                                     /*IsExternal*/ false, Sym.getGeneric());
       Prevailing = true;
     }
+
     if (Prevailing) {
-      SectionChunk *C = readSection(SectionNumber, Def, Name);
+      SectionChunk *C = readSection(SectionNumber, Def, GetName());
       SparseChunks[SectionNumber] = C;
       C->Sym = cast<DefinedRegular>(Leader);
       cast<DefinedRegular>(Leader)->Data = &C->Repl;
     } else {
       SparseChunks[SectionNumber] = nullptr;
     }
     return Leader;
   }

lld/trunk/test/COFF/invalid-section-number.test

+# RUN: yaml2obj %s > %t.obj
+# RUN: not lld-link %t.obj 2>&1 | FileCheck %s
+
+# CHECK: foo should not refer to special section -10
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_I386
+  Characteristics: []
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       4
+    SectionData:     B82A000000C3
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          6
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          0
+  - Name:            foo
+    Value:           0
+    SectionNumber:   -10
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...