[CommandLineParser] Add DefaultOption flag

Summary: Add DefaultOption flag to CommandLineParser which provides a
default option or alias, but allows users to override it for some
other purpose as needed.

Also, add `-h` as a default alias to `-help`, which can be seamlessly
overridden by applications like llvm-objdump and llvm-readobj which
use `-h` as an alias for other options.

(relanding after revert, r358414)
Added DefaultOptions.clear() to reset().

Reviewers: alexfh, klimek

Reviewed By: klimek

Subscribers: kristina, MaskRay, mehdi_amini, inglorion, dexonsmith, hiraditya, llvm-commits, jhenderson, arphaman, cfe-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D59746

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358428 91177308-0d34-0410-b5e6-96231b3b80d8

docs/CommandLine.rst

@@ -128,6 +128,7 @@ this:
   USAGE: compiler [options]
 
   OPTIONS:
+    -h                - Alias for -help
     -help             - display available options (-help-hidden for more)
     -o <filename>     - Specify output filename
 
@@ -194,6 +195,7 @@ declarations above, the ``-help`` option synopsis is now extended to:
   USAGE: compiler [options] <input file>
 
   OPTIONS:
+    -h                - Alias for -help
     -help             - display available options (-help-hidden for more)
     -o <filename>     - Specify output filename
 
@@ -1251,6 +1253,14 @@ specify boolean properties that modify the option.
   with ``cl::CommaSeparated``, this modifier only makes sense with a `cl::list`_
   option.
 
+.. _cl::DefaultOption:
+
+* The **cl::DefaultOption** modifier is used to specify that the option is a
+  default that can be overridden by application specific parsers. For example,
+  the ``-help`` alias, ``-h``, is registered this way, so it can be overridden
+  by applications that need to use the ``-h`` option for another purpose,
+  either as a regular option or an alias for another option.
+
 .. _response files:
 
 Response files

include/llvm/Support/CommandLine.h

@@ -175,7 +175,10 @@ enum MiscFlags {             // Miscellaneous flags to adjust argument
   // If this is enabled, multiple letter options are allowed to bunch together
   // with only a single hyphen for the whole group.  This allows emulation
   // of the behavior that ls uses for example: ls -la === ls -l -a
-  Grouping = 0x08
+  Grouping = 0x08,
+
+  // Default option
+  DefaultOption = 0x10
 };
 
 //===----------------------------------------------------------------------===//
@@ -270,7 +273,7 @@ class Option {
   unsigned Value : 2;
   unsigned HiddenFlag : 2; // enum OptionHidden
   unsigned Formatting : 2; // enum FormattingFlags
-  unsigned Misc : 4;
+  unsigned Misc : 5;
   unsigned Position = 0;       // Position of last occurrence of the option
   unsigned AdditionalVals = 0; // Greater than 0 for multi-valued option.
 
@@ -306,6 +309,7 @@ public:
   bool hasArgStr() const { return !ArgStr.empty(); }
   bool isPositional() const { return getFormattingFlag() == cl::Positional; }
   bool isSink() const { return getMiscFlags() & cl::Sink; }
+  bool isDefaultOption() const { return getMiscFlags() & cl::DefaultOption; }
 
   bool isConsumeAfter() const {
     return getNumOccurrencesFlag() == cl::ConsumeAfter;
@@ -382,7 +386,7 @@ public:
   }
 
   inline int getNumOccurrences() const { return NumOccurrences; }
-  inline void reset() { NumOccurrences = 0; }
+  void reset();
 };
 
 //===----------------------------------------------------------------------===//
@@ -1732,7 +1736,10 @@ class alias : public Option {
       error("cl::alias must have argument name specified!");
     if (!AliasFor)
       error("cl::alias must have an cl::aliasopt(option) specified!");
+    if (!Subs.empty())
+      error("cl::alias must not have cl::sub(), aliased option's cl::sub() will be used!");
     Subs = AliasFor->Subs;
+    Category = AliasFor->Category;
     addArgument();
   }
 

lib/Support/CommandLine.cpp

@@ -98,6 +98,11 @@ public:
   // This collects additional help to be printed.
   std::vector<StringRef> MoreHelp;
 
+  // This collects Options added with the cl::DefaultOption flag. Since they can
+  // be overridden, they are not added to the appropriate SubCommands until
+  // ParseCommandLineOptions actually runs.
+  SmallVector<Option*, 4> DefaultOptions;
+
   // This collects the different option categories that have been registered.
   SmallPtrSet<OptionCategory *, 16> RegisteredOptionCategories;
 
@@ -146,6 +151,11 @@ public:
   void addOption(Option *O, SubCommand *SC) {
     bool HadErrors = false;
     if (O->hasArgStr()) {
+      // If it's a DefaultOption, check to make sure it isn't already there.
+      if (O->isDefaultOption() &&
+          SC->OptionsMap.find(O->ArgStr) != SC->OptionsMap.end())
+        return;
+
       // Add argument to the argument map!
       if (!SC->OptionsMap.insert(std::make_pair(O->ArgStr, O)).second) {
         errs() << ProgramName << ": CommandLine Error: Option '" << O->ArgStr
@@ -185,7 +195,12 @@ public:
     }
   }
 
-  void addOption(Option *O) {
+  void addOption(Option *O, bool ProcessDefaultOption = false) {
+    if (!ProcessDefaultOption && O->isDefaultOption()) {
+      DefaultOptions.push_back(O);
+      return;
+    }
+
     if (O->Subs.empty()) {
       addOption(O, &*TopLevelSubCommand);
     } else {
@@ -201,8 +216,12 @@ public:
       OptionNames.push_back(O->ArgStr);
 
     SubCommand &Sub = *SC;
-    for (auto Name : OptionNames)
-      Sub.OptionsMap.erase(Name);
+    auto End = Sub.OptionsMap.end();
+    for (auto Name : OptionNames) {
+      auto I = Sub.OptionsMap.find(Name);
+      if (I != End && I->getValue() == O)
+        Sub.OptionsMap.erase(I);
+      }
 
     if (O->getFormattingFlag() == cl::Positional)
       for (auto Opt = Sub.PositionalOpts.begin();
@@ -266,8 +285,13 @@ public:
     if (O->Subs.empty())
       updateArgStr(O, NewName, &*TopLevelSubCommand);
     else {
-      for (auto SC : O->Subs)
-        updateArgStr(O, NewName, SC);
+      if (O->isInAllSubCommands()) {
+        for (auto SC : RegisteredSubCommands)
+          updateArgStr(O, NewName, SC);
+      } else {
+        for (auto SC : O->Subs)
+          updateArgStr(O, NewName, SC);
+      }
     }
   }
 
@@ -331,6 +355,8 @@ public:
     AllSubCommands->reset();
     registerSubCommand(&*TopLevelSubCommand);
     registerSubCommand(&*AllSubCommands);
+
+    DefaultOptions.clear();
   }
 
 private:
@@ -366,6 +392,13 @@ void Option::setArgStr(StringRef S) {
   ArgStr = S;
 }
 
+void Option::reset() {
+  NumOccurrences = 0;
+  setDefault();
+  if (isDefaultOption())
+    removeArgument();
+}
+
 // Initialise the general option category.
 OptionCategory llvm::cl::GeneralCategory("General options");
 
@@ -1167,6 +1200,10 @@ bool CommandLineParser::ParseCommandLineOptions(int argc,
   auto &SinkOpts = ChosenSubCommand->SinkOpts;
   auto &OptionsMap = ChosenSubCommand->OptionsMap;
 
+  for (auto O: DefaultOptions) {
+    addOption(O, true);
+  }
+
   if (ConsumeAfterOpt) {
     assert(PositionalOpts.size() > 0 &&
            "Cannot specify cl::ConsumeAfter without a positional argument!");
@@ -2146,6 +2183,9 @@ static cl::opt<HelpPrinterWrapper, true, parser<bool>>
         cl::location(WrappedNormalPrinter), cl::ValueDisallowed,
         cl::cat(GenericCategory), cl::sub(*AllSubCommands));
 
+static cl::alias HOpA("h", cl::desc("Alias for -help"), cl::aliasopt(HOp),
+                      cl::DefaultOption);
+
 static cl::opt<HelpPrinterWrapper, true, parser<bool>>
     HHOp("help-hidden", cl::desc("Display all available options"),
          cl::location(WrappedHiddenPrinter), cl::Hidden, cl::ValueDisallowed,

test/Support/check-default-options.txt

@@ -0,0 +1,18 @@
+# RUN: llvm-objdump -help-hidden %t | FileCheck --check-prefix=CHECK-OBJDUMP %s
+# RUN: llvm-readobj -help-hidden %t | FileCheck --check-prefix=CHECK-READOBJ %s
+# RUN: llvm-tblgen -help-hidden %t | FileCheck --check-prefix=CHECK-TBLGEN %s
+# RUN: llvm-opt-report -help-hidden %t | FileCheck --check-prefix=CHECK-OPT-RPT %s
+# RUN: llvm-dwarfdump -help-hidden %t | FileCheck --check-prefix=CHECK-DWARF %s
+# RUN: llvm-dwarfdump -h %t | FileCheck --check-prefix=CHECK-DWARF-H %s
+
+
+# CHECK-OBJDUMP: -h  - Alias for --section-headers
+# CHECK-READOBJ: -h  - Alias for --file-headers
+# CHECK-TBLGEN:  -h  - Alias for -help
+# CHECK-OPT-RPT: -h  - Alias for -help
+# CHECK-DWARF:   -h  - Alias for -help
+
+# llvm-dwarfdump declares `-h` option and prints special help in that case,
+# which is weird, but makes for a good test, i.e., shows the default `-h`
+# wasn't used.
+# CHECK-DWARF-H-NOT: -help-list  - Display list of available options (-help-list-hidden for more)

tools/llvm-opt-report/OptReport.cpp

@@ -36,8 +36,6 @@
 using namespace llvm;
 using namespace llvm::yaml;
 
-static cl::opt<bool> Help("h", cl::desc("Alias for -help"), cl::Hidden);
-
 // Mark all our options with this category, everything else (except for -version
 // and -help) will be hidden.
 static cl::OptionCategory
@@ -440,11 +438,6 @@ int main(int argc, const char **argv) {
       "A tool to generate an optimization report from YAML optimization"
       " record files.\n");
 
-  if (Help) {
-    cl::PrintHelpMessage();
-    return 0;
-  }
-
   LocationInfoTy LocationInfo;
   if (!readLocationInfo(LocationInfo))
     return 1;

unittests/Support/CommandLineTest.cpp

@@ -620,6 +620,68 @@ TEST(CommandLineTest, GetRegisteredSubcommands) {
   }
 }
 
+TEST(CommandLineTest, DefaultOptions) {
+  cl::ResetCommandLineParser();
+
+  StackOption<std::string> Bar("bar", cl::sub(*cl::AllSubCommands),
+                               cl::DefaultOption);
+  StackOption<std::string, cl::alias> Bar_Alias(
+      "b", cl::desc("Alias for -bar"), cl::aliasopt(Bar), cl::DefaultOption);
+
+  StackOption<bool> Foo("foo", cl::init(false), cl::sub(*cl::AllSubCommands),
+                        cl::DefaultOption);
+  StackOption<bool, cl::alias> Foo_Alias("f", cl::desc("Alias for -foo"),
+                                         cl::aliasopt(Foo), cl::DefaultOption);
+
+  StackSubCommand SC1("sc1", "First Subcommand");
+  // Override "-b" and change type in sc1 SubCommand.
+  StackOption<bool> SC1_B("b", cl::sub(SC1), cl::init(false));
+  StackSubCommand SC2("sc2", "Second subcommand");
+  // Override "-foo" and change type in sc2 SubCommand.  Note that this does not
+  // affect "-f" alias, which continues to work correctly.
+  StackOption<std::string> SC2_Foo("foo", cl::sub(SC2));
+
+  const char *args0[] = {"prog", "-b", "args0 bar string", "-f"};
+  EXPECT_TRUE(cl::ParseCommandLineOptions(sizeof(args0) / sizeof(char *), args0,
+                                          StringRef(), &llvm::nulls()));
+  EXPECT_TRUE(Bar == "args0 bar string");
+  EXPECT_TRUE(Foo);
+  EXPECT_FALSE(SC1_B);
+  EXPECT_TRUE(SC2_Foo.empty());
+
+  cl::ResetAllOptionOccurrences();
+
+  const char *args1[] = {"prog", "sc1", "-b", "-bar", "args1 bar string", "-f"};
+  EXPECT_TRUE(cl::ParseCommandLineOptions(sizeof(args1) / sizeof(char *), args1,
+                                          StringRef(), &llvm::nulls()));
+  EXPECT_TRUE(Bar == "args1 bar string");
+  EXPECT_TRUE(Foo);
+  EXPECT_TRUE(SC1_B);
+  EXPECT_TRUE(SC2_Foo.empty());
+  for (auto *S : cl::getRegisteredSubcommands()) {
+    if (*S) {
+      EXPECT_EQ("sc1", S->getName());
+    }
+  }
+
+  cl::ResetAllOptionOccurrences();
+
+  const char *args2[] = {"prog", "sc2", "-b", "args2 bar string",
+                         "-f", "-foo", "foo string"};
+  EXPECT_TRUE(cl::ParseCommandLineOptions(sizeof(args2) / sizeof(char *), args2,
+                                          StringRef(), &llvm::nulls()));
+  EXPECT_TRUE(Bar == "args2 bar string");
+  EXPECT_TRUE(Foo);
+  EXPECT_FALSE(SC1_B);
+  EXPECT_TRUE(SC2_Foo == "foo string");
+  for (auto *S : cl::getRegisteredSubcommands()) {
+    if (*S) {
+      EXPECT_EQ("sc2", S->getName());
+    }
+  }
+  cl::ResetCommandLineParser();
+}
+
 TEST(CommandLineTest, ArgumentLimit) {
   std::string args(32 * 4096, 'a');
   EXPECT_FALSE(llvm::sys::commandLineFitsWithinSystemLimits("cl", args.data()));