[MC] Make symbol version errors non-fatal

We stil don't have a source location, which is pretty lame, but at least
we won't tell the user to file a clang bug report anymore.

Fixes PR40712

llvm-svn: 353907

lib/MC/ELFObjectWriter.cpp

@@ -1274,14 +1274,20 @@ void ELFObjectWriter::executePostLayoutBinding(MCAssembler &Asm,
     if (!Symbol.isUndefined() && !Rest.startswith("@@@"))
       continue;
 
-    // FIXME: produce a better error message.
+    // FIXME: Get source locations for these errors or diagnose them earlier.
     if (Symbol.isUndefined() && Rest.startswith("@@") &&
-        !Rest.startswith("@@@"))
-      report_fatal_error("A @@ version cannot be undefined");
+        !Rest.startswith("@@@")) {
+      Asm.getContext().reportError(SMLoc(), "versioned symbol " + AliasName +
+                                                " must be defined");
+      continue;
+    }
 
-    if (Renames.count(&Symbol) && Renames[&Symbol] != Alias)
-      report_fatal_error(llvm::Twine("Multiple symbol versions defined for ") +
-                         Symbol.getName());
+    if (Renames.count(&Symbol) && Renames[&Symbol] != Alias) {
+      Asm.getContext().reportError(
+          SMLoc(), llvm::Twine("multiple symbol versions defined for ") +
+                       Symbol.getName());
+      continue;
+    }
 
     Renames.insert(std::make_pair(&Symbol, Alias));
   }

test/MC/ELF/invalid-symver.s

@@ -1,7 +1,7 @@
 // RUN: not llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o %t 2> %t.out
 // RUN: FileCheck --input-file=%t.out %s
 
-// CHECK: A @@ version cannot be undefined
+// CHECK: error: versioned symbol foo@@bar must be defined
 
         .symver undefined, foo@@bar
         .long undefined

test/MC/ELF/multiple-different-symver.s

@@ -1,6 +1,6 @@
 // RUN: not llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o %t 2>&1 | FileCheck %s
 
-// CHECK: Multiple symbol versions defined for foo
+// CHECK: error: multiple symbol versions defined for foo
 
 .symver foo, foo@1
 .symver foo, foo@2