Option spell checking: Penalize delimiter flags if input has no argument

If the user passes a flag like `-version` to a program, it's more likely
they mean `--version` than `-version:`, since there's no parameter
passed. Hence, give delimited arguments a penalty of 1 if the user input
doesn't contain the delimiter or no data after it.

The motivation is that with this, lld-link can suggest "--version"
instead of "-version:" for "-version" and "-nodefaultlib" instead of
"-nodefaultlib:" for "-nodefaultlibs".

Differential Revision: https://reviews.llvm.org/D61382

llvm-svn: 359701

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/Option/OptTable.cpp b/llvm/lib/Option/OptTable.cpp
index 47c5f80c7d7..5833d03069f 100644
--- a/llvm/lib/Option/OptTable.cpp
+++ b/llvm/lib/Option/OptTable.cpp
@@ -301,6 +301,15 @@ unsigned OptTable::findNearest(StringRef Option, std::string &NearestString,
       unsigned Distance =
           CandidateRef.edit_distance(NormalizedName, /*AllowReplacements=*/true,
                                      /*MaxEditDistance=*/BestDistance);
+      if (RHS.empty() && CandidateHasDelimiter) {
+        // The Candidate ends with a = or : delimiter, but the option passed in
+        // didn't contain the delimiter (or doesn't have anything after it).
+        // In that case, penalize the correction: `-nodefaultlibs` is more
+        // likely to be a spello for `-nodefaultlib` than `-nodefaultlib:` even
+        // though both have an unmodified editing distance of 1, since the
+        // latter would need an argument.
+        ++Distance;
+      }
       if (Distance < BestDistance) {
         BestDistance = Distance;
         NearestString = (Candidate + RHS).str();