Re-revert "[Option] Fix PR37006 prefix choice in findNearest"

Summary:
Reverting due to a test failure in an llvm-mt test on some buildbots, namely
http://green.lab.llvm.org/green/job/clang-stage2-configure-Rlto/26020/.

llvm-svn: 332812

3 files changed, 24 insertions, 29 deletions

diff --git a/llvm/lib/Option/OptTable.cpp b/llvm/lib/Option/OptTable.cpp
index 293b6e54e21..022b9d5d933 100644
--- a/llvm/lib/Option/OptTable.cpp
+++ b/llvm/lib/Option/OptTable.cpp
@@ -252,33 +252,38 @@ unsigned OptTable::findNearest(StringRef Option, std::string &NearestString,
                                unsigned MinimumLength) const {
   assert(!Option.empty());
 
-  // Consider each [option prefix + option name] pair as a candidate, finding
-  // the closest match.
+  // Consider each option as a candidate, finding the closest match.
   unsigned BestDistance = UINT_MAX;
   for (const Info &CandidateInfo :
        ArrayRef<Info>(OptionInfos).drop_front(FirstSearchableIndex)) {
     StringRef CandidateName = CandidateInfo.Name;
 
-    // We can eliminate some option prefix/name pairs as candidates right away:
-    // * Ignore option candidates with empty names, such as "--", or names
-    //   that do not meet the minimum length.
+    // Ignore option candidates with empty names, such as "--", or names
+    // that do not meet the minimum length.
     if (CandidateName.empty() || CandidateName.size() < MinimumLength)
       continue;
 
-    // * If FlagsToInclude were specified, ignore options that don't include
-    //   those flags.
+    // If FlagsToInclude were specified, ignore options that don't include
+    // those flags.
     if (FlagsToInclude && !(CandidateInfo.Flags & FlagsToInclude))
       continue;
-    // * Ignore options that contain the FlagsToExclude.
+    // Ignore options that contain the FlagsToExclude.
     if (CandidateInfo.Flags & FlagsToExclude)
       continue;
 
-    // * Ignore positional argument option candidates (which do not
-    //   have prefixes).
+    // Ignore positional argument option candidates (which do not
+    // have prefixes).
     if (!CandidateInfo.Prefixes)
       continue;
+    // Find the most appropriate prefix. For example, if a user asks for
+    // "--helm", suggest "--help" over "-help".
+    StringRef Prefix = CandidateInfo.Prefixes[0];
+    for (int P = 1; CandidateInfo.Prefixes[P]; P++) {
+      if (Option.startswith(CandidateInfo.Prefixes[P]))
+        Prefix = CandidateInfo.Prefixes[P];
+    }
 
-    // Now check if the candidate ends with a character commonly used when
+    // Check if the candidate ends with a character commonly used when
     // delimiting an option from its value, such as '=' or ':'. If it does,
     // attempt to split the given option based on that delimiter.
     std::string Delimiter = "";
@@ -292,19 +297,14 @@ unsigned OptTable::findNearest(StringRef Option, std::string &NearestString,
     else
       std::tie(LHS, RHS) = Option.split(Last);
 
-    // Consider each possible prefix for each candidate to find the most
-    // appropriate one. For example, if a user asks for "--helm", suggest
-    // "--help" over "-help".
-    for (int P = 0; const char *const CandidatePrefix = CandidateInfo.Prefixes[P]; P++) {
-      std::string NormalizedName = (LHS + Delimiter).str();
-      StringRef Candidate = (CandidatePrefix + CandidateName).str();
-      unsigned Distance =
-          Candidate.edit_distance(NormalizedName, /*AllowReplacements=*/true,
-                                  /*MaxEditDistance=*/BestDistance);
-      if (Distance < BestDistance) {
-        BestDistance = Distance;
-        NearestString = (Candidate + RHS).str();
-      }
+    std::string NormalizedName =
+        (LHS.drop_front(Prefix.size()) + Delimiter).str();
+    unsigned Distance =
+        CandidateName.edit_distance(NormalizedName, /*AllowReplacements=*/true,
+                                    /*MaxEditDistance=*/BestDistance);
+    if (Distance < BestDistance) {
+      BestDistance = Distance;
+      NearestString = (Prefix + CandidateName + RHS).str();
     }
   }
   return BestDistance;
diff --git a/llvm/unittests/Option/OptionParsingTest.cpp b/llvm/unittests/Option/OptionParsingTest.cpp
index 99c1ef32476..eef21ab5120 100644
--- a/llvm/unittests/Option/OptionParsingTest.cpp
+++ b/llvm/unittests/Option/OptionParsingTest.cpp
@@ -283,10 +283,6 @@ TEST(Option, FindNearest) {
   EXPECT_EQ(Nearest, "-blorp");
   EXPECT_EQ(1U, T.findNearest("--blorm", Nearest));
   EXPECT_EQ(Nearest, "--blorp");
-  EXPECT_EQ(1U, T.findNearest("-blarg", Nearest));
-  EXPECT_EQ(Nearest, "-blarn");
-  EXPECT_EQ(1U, T.findNearest("--blarm", Nearest));
-  EXPECT_EQ(Nearest, "--blarn");
   EXPECT_EQ(1U, T.findNearest("-fjormp", Nearest));
   EXPECT_EQ(Nearest, "--fjormp");
 
diff --git a/llvm/unittests/Option/Opts.td b/llvm/unittests/Option/Opts.td
index e6151d375ef..c4544b5b3f9 100644
--- a/llvm/unittests/Option/Opts.td
+++ b/llvm/unittests/Option/Opts.td
@@ -30,7 +30,6 @@ def Slurp : Option<["-"], "slurp", KIND_REMAINING_ARGS>;
 def SlurpJoined : Option<["-"], "slurpjoined", KIND_REMAINING_ARGS_JOINED>;
 
 def Blorp : Flag<["-", "--"], "blorp">, HelpText<"The blorp option">, Flags<[OptFlag1]>;
-def Blarn : Flag<["--", "-"], "blarn">, HelpText<"The blarn option">, Flags<[OptFlag1]>;
 def Cramb : Joined<["/"], "cramb:">, HelpText<"The cramb option">, MetaVarName<"CRAMB">, Flags<[OptFlag1]>;
 def Doopf1 : Flag<["-"], "doopf1">, HelpText<"The doopf1 option">, Flags<[OptFlag1]>;
 def Doopf2 : Flag<["-"], "doopf2">, HelpText<"The doopf2 option">, Flags<[OptFlag2]>;