llvm-link: Improve diagnostic for module-level metadata mismatch

This might produce hard to read/illegible diagnostics for especially
weird/non-trivial module metadata but integers are about all we are
using these days, so seems more useful than not.

Patch based on work by Kristina Brooks - thanks!

Differential Revision: https://reviews.llvm.org/D52952

llvm-svn: 344011

1 files changed, 8 insertions, 2 deletions

diff --git a/llvm/lib/Linker/IRMover.cpp b/llvm/lib/Linker/IRMover.cpp
index 48b746a22fc..b304bfc401a 100644
--- a/llvm/lib/Linker/IRMover.cpp
+++ b/llvm/lib/Linker/IRMover.cpp
@@ -1230,8 +1230,14 @@ Error IRLinker::linkModuleFlagsMetadata() {
     case Module::Warning: {
       // Emit a warning if the values differ.
       if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
-        emitWarning("linking module flags '" + ID->getString() +
-                    "': IDs have conflicting values");
+        std::string str;
+        raw_string_ostream(str)
+            << "linking module flags '" << ID->getString()
+            << "': IDs have conflicting values ('" << *SrcOp->getOperand(2)
+            << "' from " << SrcM->getModuleIdentifier() << " with '"
+            << *DstOp->getOperand(2) << "' from " << DstM.getModuleIdentifier()
+            << ')';
+        emitWarning(str);
       }
       continue;
     }