[llvm] [OptTable] Make new lines in help text respect indentation (PR #75366)

[Andres Villegas via llvm-commits]

https://github.com/avillega created https://github.com/llvm/llvm-project/pull/75366

With this changes, new lines in the HelpText defined in OptTable have the same indentation as the first line.

Before, the help output will look something like:

```
--color=<value>       Whether to use color when
symbolizing log markup: always, auto, never
```

With this change:

```
--color=<value>       - Whether to use color when
                        symbolizing log markup: always, auto, never
```

Note the "-" at the beginning of the help text in the new version, it was added to clearly separate the HelpText of the different options.

>From 1172255ee8ff6c7ca19a3fdeb23b5f55a19288ec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9s=20Villegas?= <andresvi at google.com>
Date: Tue, 12 Dec 2023 19:30:47 +0000
Subject: [PATCH] [OptTable] Make new lines in help text respect indentation

With this changes, new lines in the HelpText defined
in OptTable have the same indentation as the first line.

Before, the help output will look something like:

```
--color=<value>       Whether to use color when
symbolizing log markup: always, auto, never
```

With this change:

```
--color=<value>       - Whether to use color when
                        symbolizing log markup: always, auto, never
```

Note the "-" at the beginning of the help text in the new version,
it was added to clearly separate the HelpText of the different
options.
---
 llvm/lib/Option/OptTable.cpp                | 17 ++++++++++++----
 llvm/unittests/Option/OptionParsingTest.cpp | 22 +++++++++++++++++++++
 llvm/unittests/Option/Opts.td               | 11 +++++++++++
 3 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Option/OptTable.cpp b/llvm/lib/Option/OptTable.cpp
index a4d0f4a5493725..cf69f6173b6d41 100644
--- a/llvm/lib/Option/OptTable.cpp
+++ b/llvm/lib/Option/OptTable.cpp
@@ -664,15 +664,24 @@ static void PrintHelpOptionList(raw_ostream &OS, StringRef Title,
   const unsigned InitialPad = 2;
   for (const OptionInfo &Opt : OptionHelp) {
     const std::string &Option = Opt.Name;
-    int Pad = OptionFieldWidth - int(Option.size());
+    int Pad = OptionFieldWidth + InitialPad;
+    int FirstLinePad = OptionFieldWidth - int(Option.size());
     OS.indent(InitialPad) << Option;
 
     // Break on long option names.
-    if (Pad < 0) {
+    if (FirstLinePad < 0) {
       OS << "\n";
-      Pad = OptionFieldWidth + InitialPad;
+      FirstLinePad = OptionFieldWidth + InitialPad;
+      Pad = FirstLinePad;
     }
-    OS.indent(Pad + 1) << Opt.HelpText << '\n';
+
+    SmallVector<StringRef> Lines;
+    Opt.HelpText.split(Lines, '\n');
+    assert(Lines.size() && "Expected at least the first line in the help text");
+    auto *LinesIt = Lines.begin();
+    OS.indent(FirstLinePad + 1) << *LinesIt << '\n';
+    while (Lines.end() != ++LinesIt)
+      OS.indent(Pad + 1) << *LinesIt << '\n';
   }
 }
 
diff --git a/llvm/unittests/Option/OptionParsingTest.cpp b/llvm/unittests/Option/OptionParsingTest.cpp
index 804a8016414dbc..cd8743e49d4fde 100644
--- a/llvm/unittests/Option/OptionParsingTest.cpp
+++ b/llvm/unittests/Option/OptionParsingTest.cpp
@@ -9,6 +9,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
+#include "llvm/Option/OptTable.h"
 #include "llvm/Option/Option.h"
 #include "gtest/gtest.h"
 
@@ -50,6 +51,7 @@ enum OptionFlags {
 
 enum OptionVisibility {
   SubtoolVis = (1 << 2),
+  MultiLineVis = (1 << 3),
 };
 
 static constexpr OptTable::Info InfoTable[] = {
@@ -538,3 +540,23 @@ TYPED_TEST(OptTableTest, UnknownGroupedShortOptions) {
   EXPECT_EQ("-u", Unknown[2]);
   EXPECT_EQ("-z", Unknown[3]);
 }
+
+TYPED_TEST(OptTableTest, PrintMultilineHelpText) {
+  TypeParam T;
+  std::string Help;
+  raw_string_ostream RSO(Help);
+  T.printHelp(RSO, "usage", "title", /*ShowHidden=*/false,
+              /*ShowAllAliases=*/false, Visibility(MultiLineVis));
+  EXPECT_STREQ(Help.c_str(), R"(OVERVIEW: title
+
+USAGE: usage
+
+OPTIONS:
+  -multiline-help-with-long-name
+                  This a help text that has
+                  multiple lines in it
+                  and a long name
+  -multiline-help This a help text that has
+                  multiple lines in it
+)");
+}
diff --git a/llvm/unittests/Option/Opts.td b/llvm/unittests/Option/Opts.td
index ac01d6d93b2b63..550d804daae0b1 100644
--- a/llvm/unittests/Option/Opts.td
+++ b/llvm/unittests/Option/Opts.td
@@ -5,6 +5,7 @@ def OptFlag2 : OptionFlag;
 def OptFlag3 : OptionFlag;
 
 def SubtoolVis : OptionVisibility;
+def MultiLineVis: OptionVisibility;
 
 def A : Flag<["-"], "A">, HelpText<"The A option">, Flags<[OptFlag1]>;
 def AB : Flag<["-"], "AB">;
@@ -50,6 +51,16 @@ def Blurmpq_eq : Flag<["--"], "blurmp=">;
 def Q : Flag<["-"], "Q">, Visibility<[SubtoolVis]>;
 def R : Flag<["-"], "R">, Visibility<[DefaultVis, SubtoolVis]>;
 
+def multiline_help : Flag<["-"], "multiline-help">, HelpText<"This a help text that has\nmultiple lines in it">, Visibility<[MultiLineVis]>;
+
+def multiline_help_long : 
+  Flag<["-"], "multiline-help-with-long-name">, 
+  HelpText<"This a help text that has\n"
+           "multiple lines in it\n"
+           "and a long name">,
+  Visibility<[MultiLineVis]>;
+
+
 class XOpts<string base> : KeyPathAndMacro<"X->", base> {}
 
 def marshalled_flag_d : Flag<["-"], "marshalled-flag-d">,