[llvm-readobj/libObject] - Introduce a custom warning handler for `ELFFile<ELFT>` methods.

Currently, we have a code duplication in llvm-readobj which was introduced in D63266.
The duplication was introduced to allow llvm-readobj to dump the partially
broken object. Methods in ELFFile<ELFT> perform a strict validation of the inputs,
what is itself good, but not for dumper tools, that might want to dump the information,
even if some pieces are broken/unexpected.

This patch introduces a warning handler which can be passed to ELFFile<ELFT> methods
and can allow skipping the non-critical errors when needed/possible.

For demonstration, I removed the duplication from llvm-readobj and implemented a warning using
the new custom warning handler. It also deduplicates the strings printed, making the output less verbose.

Differential revision: https://reviews.llvm.org/D65515

llvm-svn: 368260

1 files changed, 10 insertions, 0 deletions

diff --git a/llvm/tools/llvm-readobj/llvm-readobj.h b/llvm/tools/llvm-readobj/llvm-readobj.h
index 0e02da4..7ca1dfb 100644
--- a/llvm/tools/llvm-readobj/llvm-readobj.h
+++ b/llvm/tools/llvm-readobj/llvm-readobj.h
@@ -24,6 +24,7 @@ namespace llvm {
   LLVM_ATTRIBUTE_NORETURN void reportError(Twine Msg);
   void reportError(StringRef Input, Error Err); 
   void reportWarning(Twine Msg);
+  void reportWarning(StringRef Input, Error Err);
   void warn(llvm::Error Err);
   void error(std::error_code EC);
   void error(llvm::Error EC);
@@ -37,6 +38,8 @@ namespace llvm {
       return *EO;
     reportError(EO.getError().message());
   }
+
+  // TODO: This one is deprecated. Use one with a Input name below.
   template <class T> T unwrapOrError(Expected<T> EO) {
     if (EO)
       return *EO;
@@ -46,6 +49,13 @@ namespace llvm {
     OS.flush();
     reportError(Buf);
   }
+
+  template <class T> T unwrapOrError(StringRef Input, Expected<T> EO) {
+    if (EO)
+      return *EO;
+    reportError(Input, EO.takeError());
+    llvm_unreachable("reportError shouldn't return in this case");
+  }
 } // namespace llvm
 
 namespace opts {