Recommit: Add support for prefix-only CLI options

Summary:
Add support for options that always prefix their value, giving an error
if the value is in the next argument or if the option is given a value
assignment (ie. opt=val). This is the desired behavior for the -D option
of FileCheck for instance.

Copyright:
- Linaro (changes in version 2 of revision D55940)
- GraphCore (changes in later versions and introduced when creating
  D56549)

Reviewers: jdenny

Subscribers: llvm-commits, probinson, kristina, hiraditya,
JonChesterfield

Differential Revision: https://reviews.llvm.org/D56549

llvm-svn: 353172
(cherry picked from LLVM commit f929a0f81b6f75f880796b3716ab8a858a764de9)

Author: Thomas Preud'homme

include/llvm/Support/CommandLine.h

@@ -134,6 +134,9 @@ enum OptionHidden {   // Control whether -help shows this option
 // enabled, and used, the value for the flag comes from the suffix of the
 // argument.
 //
+// AlwaysPrefix - Only allow the behavior enabled by the Prefix flag and reject
+// the Option=Value form.
+//
 // Grouping - With this option 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
@@ -143,7 +146,8 @@ enum FormattingFlags {
   NormalFormatting = 0x00, // Nothing special
   Positional = 0x01,       // Is a positional argument, no '-' required
   Prefix = 0x02,           // Can this option directly prefix its value?
-  Grouping = 0x03          // Can this option group with other options?
+  AlwaysPrefix = 0x03,     // Can this option only directly prefix its value?
+  Grouping = 0x04          // Can this option group with other options?
 };
 
 enum MiscFlags {             // Miscellaneous flags to adjust argument
@@ -242,7 +246,7 @@ class Option {
   // detail representing the non-value
   unsigned Value : 2;
   unsigned HiddenFlag : 2; // enum OptionHidden
-  unsigned Formatting : 2; // enum FormattingFlags
+  unsigned Formatting : 3; // enum FormattingFlags
   unsigned Misc : 3;
   unsigned Position;       // Position of last occurrence of the option
   unsigned AdditionalVals; // Greater than 0 for multi-valued option.

lib/Support/CommandLine.cpp

@@ -417,12 +417,17 @@ Option *CommandLineParser::LookupOption(SubCommand &Sub, StringRef &Arg,
     return I != Sub.OptionsMap.end() ? I->second : nullptr;
   }
 
-  // If the argument before the = is a valid option name, we match.  If not,
-  // return Arg unmolested.
+  // If the argument before the = is a valid option name and the option allows
+  // non-prefix form (ie is not AlwaysPrefix), we match.  If not, signal match
+  // failure by returning nullptr.
   auto I = Sub.OptionsMap.find(Arg.substr(0, EqualPos));
   if (I == Sub.OptionsMap.end())
     return nullptr;
 
+  auto O = I->second;
+  if (O->getFormattingFlag() == cl::AlwaysPrefix)
+    return nullptr;
+
   Value = Arg.substr(EqualPos + 1);
   Arg = Arg.substr(0, EqualPos);
   return I->second;
@@ -534,7 +539,9 @@ static inline bool ProvideOption(Option *Handler, StringRef ArgName,
   switch (Handler->getValueExpectedFlag()) {
   case ValueRequired:
     if (!Value.data()) { // No value specified?
-      if (i + 1 >= argc)
+      // If no other argument or the option only supports prefix form, we
+      // cannot look at the next argument.
+      if (i + 1 >= argc || Handler->getFormattingFlag() == cl::AlwaysPrefix)
         return Handler->error("requires a value!");
       // Steal the next argument, like for '-o filename'
       assert(argv && "null check");
@@ -592,7 +599,8 @@ static inline bool isGrouping(const Option *O) {
   return O->getFormattingFlag() == cl::Grouping;
 }
 static inline bool isPrefixedOrGrouping(const Option *O) {
-  return isGrouping(O) || O->getFormattingFlag() == cl::Prefix;
+  return isGrouping(O) || O->getFormattingFlag() == cl::Prefix ||
+         O->getFormattingFlag() == cl::AlwaysPrefix;
 }
 
 // getOptionPred - Check to see if there are any options that satisfy the
@@ -642,7 +650,8 @@ HandlePrefixedOrGroupedOption(StringRef &Arg, StringRef &Value,
   // If the option is a prefixed option, then the value is simply the
   // rest of the name...  so fall through to later processing, by
   // setting up the argument name flags and value fields.
-  if (PGOpt->getFormattingFlag() == cl::Prefix) {
+  if (PGOpt->getFormattingFlag() == cl::Prefix ||
+      PGOpt->getFormattingFlag() == cl::AlwaysPrefix) {
     Value = Arg.substr(Length);
     Arg = Arg.substr(0, Length);
     assert(OptionsMap.count(Arg) && OptionsMap.find(Arg)->second == PGOpt);

unittests/Support/CommandLineTest.cpp

@@ -45,9 +45,8 @@ class TempEnvVar {
   const char *const name;
 };
 
-template <typename T>
-class StackOption : public cl::opt<T> {
-  typedef cl::opt<T> Base;
+template <typename T, typename Base = cl::opt<T>>
+class StackOption : public Base {
 public:
   // One option...
   template<class M0t>
@@ -480,4 +479,73 @@ TEST(CommandLineTest, RemoveFromAllSubCommands) {
   EXPECT_FALSE(cl::ParseCommandLineOptions(3, args2, nullptr, true));
 }
 
+TEST(CommandLineTest, PrefixOptions) {
+  cl::ResetCommandLineParser();
+
+  StackOption<std::string, cl::list<std::string>> IncludeDirs(
+      "I", cl::Prefix, cl::desc("Declare an include directory"));
+
+  // Test non-prefixed variant works with cl::Prefix options.
+  EXPECT_TRUE(IncludeDirs.empty());
+  const char *args[] = {"prog", "-I=/usr/include"};
+  EXPECT_TRUE(cl::ParseCommandLineOptions(2, args, "", /*IgnoreErrors*/ true));
+  EXPECT_TRUE(IncludeDirs.size() == 1);
+  EXPECT_TRUE(IncludeDirs.front().compare("/usr/include") == 0);
+
+  IncludeDirs.erase(IncludeDirs.begin());
+  cl::ResetAllOptionOccurrences();
+
+  // Test non-prefixed variant works with cl::Prefix options when value is
+  // passed in following argument.
+  EXPECT_TRUE(IncludeDirs.empty());
+  const char *args2[] = {"prog", "-I", "/usr/include"};
+  EXPECT_TRUE(cl::ParseCommandLineOptions(3, args2, "", /*IgnoreErrors*/ true));
+  EXPECT_TRUE(IncludeDirs.size() == 1);
+  EXPECT_TRUE(IncludeDirs.front().compare("/usr/include") == 0);
+
+  IncludeDirs.erase(IncludeDirs.begin());
+  cl::ResetAllOptionOccurrences();
+
+  // Test prefixed variant works with cl::Prefix options.
+  EXPECT_TRUE(IncludeDirs.empty());
+  const char *args3[] = {"prog", "-I/usr/include"};
+  EXPECT_TRUE(cl::ParseCommandLineOptions(2, args3, "", /*IgnoreErrors*/ true));
+  EXPECT_TRUE(IncludeDirs.size() == 1);
+  EXPECT_TRUE(IncludeDirs.front().compare("/usr/include") == 0);
+
+  StackOption<std::string, cl::list<std::string>> MacroDefs(
+      "D", cl::AlwaysPrefix, cl::desc("Define a macro"),
+      cl::value_desc("MACRO[=VALUE]"));
+
+  cl::ResetAllOptionOccurrences();
+
+  // Test non-prefixed variant does not work with cl::AlwaysPrefix options:
+  // equal sign is part of the value.
+  EXPECT_TRUE(MacroDefs.empty());
+  const char *args4[] = {"prog", "-D=HAVE_FOO"};
+  EXPECT_TRUE(cl::ParseCommandLineOptions(2, args4, "", /*IgnoreErrors*/ true));
+  EXPECT_TRUE(MacroDefs.size() == 1);
+  EXPECT_TRUE(MacroDefs.front().compare("=HAVE_FOO") == 0);
+
+  MacroDefs.erase(MacroDefs.begin());
+  cl::ResetAllOptionOccurrences();
+
+  // Test non-prefixed variant does not allow value to be passed in following
+  // argument with cl::AlwaysPrefix options.
+  EXPECT_TRUE(MacroDefs.empty());
+  const char *args5[] = {"prog", "-D", "HAVE_FOO"};
+  EXPECT_FALSE(
+      cl::ParseCommandLineOptions(3, args5, "", /*IgnoreErrors*/ true));
+  EXPECT_TRUE(MacroDefs.empty());
+
+  cl::ResetAllOptionOccurrences();
+
+  // Test prefixed variant works with cl::AlwaysPrefix options.
+  EXPECT_TRUE(MacroDefs.empty());
+  const char *args6[] = {"prog", "-DHAVE_FOO"};
+  EXPECT_TRUE(cl::ParseCommandLineOptions(2, args6, "", /*IgnoreErrors*/ true));
+  EXPECT_TRUE(MacroDefs.size() == 1);
+  EXPECT_TRUE(MacroDefs.front().compare("HAVE_FOO") == 0);
+}
+
 }  // anonymous namespace