[lld][WebAssembly] Improve error reporting for bad ar archive members

[sbc100]

Summary

Show the name of of the archive in the error message as well as the name
of the object within it.

[sbc100]

• whitespace

[sbc100]

• require

[dschuff]

lld/test/wasm/bad-archive-member.s

2

Why does this need x86? It's a little odd that we are building an x86 object and then linking with wasm-ld?

[sbc100]

lld/test/wasm/bad-archive-member.s

2

Because that is the precise error condition we want to check for here. We need to create a llvm-ar archive with a valid index, but whose objects are no valid under wasm.

[dschuff]

lld/test/wasm/bad-archive-member.s

2

oh right, yeah makes sense.

lld/test/wasm/bad-archive-member.s

+# REQUIRES: x86
+
+# RUN: rm -rf %t.dir
+# RUN: mkdir -p %t.dir
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux -o %t.dir/elf.o %s
+# RUN: llvm-ar rcs %t.dir/libfoo.a %t.dir/elf.o
+# RUN: not wasm-ld %t.dir/libfoo.a -o /dev/null 2>&1 | FileCheck %s
+# CHECK: error: unknown file type: {{.*}}libfoo.a(elf.o)
+
+.globl _start
+_start:

lld/wasm/InputFiles.cpp

if (magic == file_magic::wasm_object) {
     if (obj->isSharedObject())
       return make<SharedFile>(mb);
     return make<ObjFile>(mb, archiveName);
   }
 
   if (magic == file_magic::bitcode)
     return make<BitcodeFile>(mb, archiveName, offsetInArchive);
 
-  fatal("unknown file type: " + mb.getBufferIdentifier());
+  std::string name = mb.getBufferIdentifier().str();
+  if (!archiveName.empty()) {
+    name = archiveName.str() + "(" + name + ")";
+  }
+
+  fatal("unknown file type: " + name);
 }
 
 // Relocations contain either symbol or type indices.  This function takes a
 // relocation and returns relocated index (i.e. translates from the input
 // symbol/type space to the output symbol/type space).
 uint32_t ObjFile::calcNewIndex(const WasmRelocation &reloc) const {
   if (reloc.Type == R_WASM_TYPE_INDEX_LEB) {
     assert(typeIsUsed[reloc.Index]);