[lldb] Warn the user about starting the --func-regex parameter with an asterisk

Summary:
Sometimes users think that setting a function regex for all function that contain the word 'needle' in their
name looks like this: `*needle*`. However, LLDB only searches the function name and doesn't fully match
it against the regex, so the leading and trailing '*' operators don't do anything and actually just cause the
regex engine to reject the regular expression with "repetition-operator operand invalid".

This patch makes this a bit more obvious to the user by printing a warning that a leading '*' before this
regular expression here doesn't have any purpose (and will cause an error). This doesn't attempt to detect
a case where there is only a trailing '*' as that would involve parsing the regex and it seems the most
common way to end up in this situation is by doing `rbreak *needle*`.

Reviewers: JDevlieghere

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D78809

1 files changed, 8 insertions, 0 deletions

diff --git a/lldb/source/Commands/CommandObjectBreakpoint.cpp b/lldb/source/Commands/CommandObjectBreakpoint.cpp
index 661ebc7..e62a115 100644
--- a/lldb/source/Commands/CommandObjectBreakpoint.cpp
+++ b/lldb/source/Commands/CommandObjectBreakpoint.cpp
@@ -622,6 +622,14 @@ protected:
         result.AppendErrorWithFormat(
             "Function name regular expression could not be compiled: %s",
             llvm::toString(std::move(err)).c_str());
+        // Check if the incorrect regex looks like a globbing expression and
+        // warn the user about it.
+        if (!m_options.m_func_regexp.empty()) {
+          if (m_options.m_func_regexp[0] == '*' ||
+              m_options.m_func_regexp[0] == '?')
+            result.AppendWarning(
+                "Function name regex does not accept glob patterns.");
+        }
         result.SetStatus(eReturnStatusFailed);
         return false;
       }