[llvm-readobj] Print error when executed with no input files
This patch changes llvm-readelf (and llvm-readobj for consistency)
behavior to print an error when executed with no input files.
Reading from stdin can be achieved via a '-' for the input
object.
Fixes https://bugs.llvm.org/show_bug.cgi?id=46400
Differential Revision: https://reviews.llvm.org/D83704
Reviewed by: jhenderson, MaskRay, sbc, jyknight
diff --git a/llvm/docs/CommandGuide/llvm-readelf.rst b/llvm/docs/CommandGuide/llvm-readelf.rst
index f74f02c..fa54c1d 100644
--- a/llvm/docs/CommandGuide/llvm-readelf.rst
+++ b/llvm/docs/CommandGuide/llvm-readelf.rst
@@ -14,7 +14,7 @@
The :program:`llvm-readelf` tool displays low-level format-specific information
about one or more object files.
-If ``input`` is "``-``" or omitted, :program:`llvm-readelf` reads from standard
+If ``input`` is "``-``", :program:`llvm-readelf` reads from standard
input. Otherwise, it will read from the specified ``filenames``.
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