[Lldb-commits] [lldb] 76584a8 - [lldb] Fix output of `help format` (#190409)

[via lldb-commits]

Author: Sergei Barannikov
Date: 2026-04-11T15:31:42Z
New Revision: 76584a89a75f9fde609e5fc341b6458d7d4f44f4

URL: https://github.com/llvm/llvm-project/commit/76584a89a75f9fde609e5fc341b6458d7d4f44f4
DIFF: https://github.com/llvm/llvm-project/commit/76584a89a75f9fde609e5fc341b6458d7d4f44f4.diff

LOG: [lldb] Fix output of `help format` (#190409)

The output currently contains
```
            "unicode32"
            'u' or "unsigned decimal"
            'p' or
            "pointer"
            "char[]"
            "int8_t[]"
```
The 'p' and "pointer" are supposed to appear on the same line. When
we're about to print "pointer," we check whether it would exceed the
column limit (in which case, we insert a line feed). This check only
checks for spaces as separators, but in this case, "words" may be
separated by newlines as well. Look for them too.

Added: 
    

Modified: 
    lldb/source/Interpreter/CommandInterpreter.cpp
    lldb/test/API/commands/help/TestHelp.py

Removed: 
    


################################################################################
diff  --git a/lldb/source/Interpreter/CommandInterpreter.cpp b/lldb/source/Interpreter/CommandInterpreter.cpp
index abbc2992b19e8..6774794f64580 100644
--- a/lldb/source/Interpreter/CommandInterpreter.cpp
+++ b/lldb/source/Interpreter/CommandInterpreter.cpp
@@ -3182,26 +3182,41 @@ void CommandInterpreter::OutputHelpText(Stream &strm, llvm::StringRef word_text,
 
   uint32_t chars_left = max_columns;
 
-  auto nextWordLength = [](llvm::StringRef S) {
-    size_t pos = S.find(' ');
-    return pos == llvm::StringRef::npos ? S.size() : pos;
+  auto start_new_line = [&] {
+    strm.EOL();
+    strm.Indent();
+    chars_left = max_columns - indent_size;
   };
 
   while (!text.empty()) {
-    if (text.front() == '\n' ||
-        (text.front() == ' ' && nextWordLength(text.ltrim(' ')) > chars_left)) {
-      strm.EOL();
-      strm.Indent();
-      chars_left = max_columns - indent_size;
-      if (text.front() == '\n')
-        text = text.drop_front();
-      else
-        text = text.ltrim(' ');
-    } else {
-      strm.PutChar(text.front());
-      --chars_left;
+    if (text.starts_with('\n')) {
       text = text.drop_front();
+      start_new_line();
+      continue;
     }
+
+    // Calculate the size of the next fragment. A fragment is defined as zero
+    // or more spaces followed by a word (which is sequence of non-whitespace
+    // characters). It is assumed that the only possible whitespaces in the
+    // input text are ' ' and '\n'.
+    size_t word_start_pos = text.find_first_not_of(' ');
+    size_t word_end_pos = text.find_first_of(" \n", /*from=*/word_start_pos);
+    size_t fragment_size =
+        word_end_pos == llvm::StringRef::npos ? text.size() : word_end_pos;
+
+    if (fragment_size > chars_left && text.starts_with(' ')) {
+      // The fragment does not fit on the current line, but begins with a space.
+      // Break the line at the beginning of the word contained in the fragment.
+      text = text.drop_front(word_start_pos);
+      start_new_line();
+      continue;
+    }
+
+    // Print out the fragment. It fits on the current line or does not contain
+    // spaces where we could break the line.
+    strm.PutCString(text.take_front(fragment_size));
+    text = text.drop_front(fragment_size);
+    chars_left = fragment_size > chars_left ? 0 : chars_left - fragment_size;
   }
 
   strm.EOL();

diff  --git a/lldb/test/API/commands/help/TestHelp.py b/lldb/test/API/commands/help/TestHelp.py
index 8423d410ca306..c8f87c7af27de 100644
--- a/lldb/test/API/commands/help/TestHelp.py
+++ b/lldb/test/API/commands/help/TestHelp.py
@@ -239,7 +239,7 @@ def test_help_unknown_flag(self):
     def test_help_format_output(self):
         """Test that help output reaches TerminalWidth and wraps to the next
         line if needed."""
-        self.runCmd("settings set term-width 118")
+        self.runCmd("settings set term-width 105")
         self.expect(
             "help format",
             matching=True,
@@ -249,9 +249,9 @@ def test_help_format_output(self):
             ],
         )
 
-        # The length of the first line will not be exactly 108 because we split
+        # The length of the first line will not be exactly 105 because we split
         # at the last whitespace point before the limit.
-        self.runCmd("settings set term-width 108")
+        self.runCmd("settings set term-width 104")
         self.expect(
             "help format",
             matching=True,
@@ -271,6 +271,16 @@ def test_help_format_output(self):
             ],
         )
 
+        # Check that line splitting works with newline characters too. The raw
+        # input after the word "pointer" does not contain spaces among more than
+        # a hundred subsequent characters, the words are separated by newlines.
+        self.runCmd("settings set term-width 80")
+        self.expect(
+            "help format",
+            matching=True,
+            substrs=["'p' or \"pointer\""],
+        )
+
     @no_debug_info_test
     def test_help_option_group_format_options_usage(self):
         """Test that help on commands that use OptionGroupFormat options provide relevant help specific to that command."""