[LLD] [COFF] Fix reporting duplicate errors for absolute symbols

Previously this caused crashes in the reportDuplicate method.

A DefinedAbsolute doesn't have any InputFile attached to it, so we
can't report the file for the original symbol.

We could add an InputFile argument to SymbolTable::addAbsolute
only for the sake of error reporting, but even then it'd be assymetrical,
only pointing out the file containing the new conflicting definition,
not the original one.

Differential Revision: https://reviews.llvm.org/D71679

diff --git a/lld/COFF/SymbolTable.cpp b/lld/COFF/SymbolTable.cpp
index 302b05b..e6f9d70 100644 (file)
--- a/lld/COFF/SymbolTable.cpp
+++ b/lld/COFF/SymbolTable.cpp
@@ -545,6 +545,8 @@ static std::string getSourceLocationObj(ObjFile *file, SectionChunk *sc,
 
 static std::string getSourceLocation(InputFile *file, SectionChunk *sc,
                                      uint32_t offset, StringRef name) {
+  if (!file)
+    return "";
   if (auto *o = dyn_cast<ObjFile>(file))
     return getSourceLocationObj(o, sc, offset, name);
   if (auto *b = dyn_cast<BitcodeFile>(file))
@@ -566,7 +568,7 @@ void SymbolTable::reportDuplicate(Symbol *existing, InputFile *newFile,
   llvm::raw_string_ostream os(msg);
   os << "duplicate symbol: " << toString(*existing);
 
-  DefinedRegular *d = cast<DefinedRegular>(existing);
+  DefinedRegular *d = dyn_cast<DefinedRegular>(existing);
   if (d && isa<ObjFile>(d->getFile())) {
     os << getSourceLocation(d->getFile(), d->getChunk(), d->getValue(),
                             existing->getName());

diff --git a/lld/test/COFF/duplicate-absolute.s b/lld/test/COFF/duplicate-absolute.s
new file mode 100644 (file)
index 0000000..0d7e0d3
--- /dev/null
+++ b/lld/test/COFF/duplicate-absolute.s
@@ -0,0 +1,14 @@
+// REQUIRES: x86
+// RUN: llvm-mc -triple x86_64-windows-msvc -filetype obj -o %t.obj %s
+// RUN: echo -e ".globl myabsolute\nmyabsolute = 0" > %t.dupl.s
+// RUN: llvm-mc -triple x86_64-windows-msvc -filetype obj -o %t.dupl.obj %t.dupl.s
+// RUN: not lld-link /out:%t.exe %t.obj %t.dupl.obj 2>&1 | FileCheck %s
+
+// CHECK: error: duplicate symbol: myabsolute
+
+.globl myabsolute
+myabsolute = 0
+
+.globl entry
+entry:
+    ret