[lldb] Fix (unintentional) recursion in CommandObjectRegexCommand

Jim noticed that the regex command is unintentionally recursive. Let's
use the following command regex as an example:

  (lldb) com regex humm 's/([^ ]+) ([^ ]+)/p %1 %2 %1 %2/'

If we call it with arguments foo bar, thing behave as expected:

  (lldb) humm foo bar
  (...)
  foo bar foo bar

However, if we include %2 in the arguments, things break down:

  (lldb) humm fo%2o bar
  (...)
  fobaro bar fobaro bar

The problem is that the implementation of the substitution is too naive.
It substitutes the %1 token into the target template in place, then does
the %2 substitution starting with the resultant string. So if the
previous substitution introduced a %2 token, it would get processed in
the second sweep, etc.

This patch addresses the issue by walking the command once and
substituting the % variables in place.

  (lldb) humm fo%2o bar
  (...)
  fo%2o bar fo%2o bar

Furthermore, this patch also reports an error if not enough variables
were provided and add support for substituting %0.

rdar://81236994

Differential revision: https://reviews.llvm.org/D120101

1 files changed, 5 insertions, 0 deletions

diff --git a/lldb/source/Interpreter/CommandReturnObject.cpp b/lldb/source/Interpreter/CommandReturnObject.cpp
index 1b1e6996764c..798dced0f1c6 100644
--- a/lldb/source/Interpreter/CommandReturnObject.cpp
+++ b/lldb/source/Interpreter/CommandReturnObject.cpp
@@ -109,6 +109,11 @@ void CommandReturnObject::SetError(const Status &error,
   AppendError(error.AsCString(fallback_error_cstr));
 }
 
+void CommandReturnObject::SetError(llvm::Error error) {
+  if (error)
+    AppendError(llvm::toString(std::move(error)));
+}
+
 // Similar to AppendError, but do not prepend 'Status: ' to message, and don't
 // append "\n" to the end of it.