[Lldb-commits] [PATCH] D145609: [lldb] Change dwim-print to default to disabled persistent results

[Dave Lee via Phabricator via lldb-commits]

kastiglione added a comment.

@jgorbe thank you for letting me know! It's not intended that the names of 
child values are not printed. I have a fix ready for review here D146783 
.


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[Lldb-commits] [PATCH] D145609: [lldb] Change dwim-print to default to disabled persistent results

[Jorge Gorbe Moya via Phabricator via lldb-commits]

jgorbe added a comment.

By the way, I just bisected another problem to this commit: I'm seeing in some 
cases that prettyprinted values with synthetic children don't show child names 
when using `dwim-print`. So print used to show:

  (lldb) p c
  (MyClass) $0 = MyClass object with children: {
[0] = 0x6004 "hello"
  }
  (lldb) p m
  (MyMap) $1 = MyMap object with children: {
["my_key"] = 0x6011 "my_value"
  }

but now it shows

  (lldb) p c
  (MyClass)  MyClass object with children: {
0x6004 "hello"
  }
  (lldb) p m
  (MyMap)  MyMap object with children: {
0x6011 "my_value"
  }

I don't have a repro test case to share right away but I though I'd give you a 
heads-up in case the problem is easy to find from the description. Or maybe 
it's the intended behavior? I get the same behavior with `expr 
--persistent-result off -- m` so I can't tell if it's a bug or if it's just the 
expected behavior when disabling persistent results. If it's the latter, that's 
a strong argument for me to unalias `print` and restore the old behavior in the 
lldbinit file we ship to our internal users.

I'll work on a small shareable test case tomorrow anyway.


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[Lldb-commits] [PATCH] D145609: [lldb] Change dwim-print to default to disabled persistent results

[Jorge Gorbe Moya via Phabricator via lldb-commits]

jgorbe added a comment.

> Are you using persistent results? If not, how much effort is it to either 1) 
> change the tools/code that examine the output to not look for $\d+, or 2) use 
> a custom print/p alias? Honest question.

I'm not using them myself, and it's not much effort to fix the problems I've 
seen because of this. It just seemed weird to have a user-facing behavior 
change like this being committed without a rationale given.

I assumed switching to `dwim-print` would be transparent for users, and I'm not 
sure how a user that relies on these convenience variables is supposed to 
discover what happened when `print` stops producing them.

> I'd be curious to learn about some example you have in mind here.

We have a python test harness that drives a debugger session that we mainly use 
for prettyprinter tests. Then we have tests that look like:

  self.ContinueTo('StopHereForDebugger')
  self.TestPrintOutputMatches('my_variable', 'Cord of length 4: "foo\\n"')

when I ported this from gdb I couldn't find an equivalent to gdb's `output` 
command (that prints just the value), so I reached for `print` which printed 
`(Type) $0 = value` instead, and kept everything after the ' = '. It wasn't 
even using the persistent values, but the change in the output format broke it.

I also found a failure in a one-off test that worked as a minimal sanity check 
for debug builds: build a debug binary, then run the debugger on it and try to 
print some variables in order to verify that debug builds do have debug info 
that the debugger can use (i.e. debug info is not completely missing, or 
corrupted). This is a shell script that basically does:

  OUTPUT=$("$LLDB" -b -s "$SCRIPT_FILE" "$TEST_PROGRAM")

and then used the conveniently sequentially-numbered persistent results to grep 
the output:

  # Check that `argc` is 1 and has type `int`.
  (echo "$OUTPUT" | grep "(int).*[$]0 = 1") || die

I know they're not the most robust tests in the world, and as I said, it was 
not much effort to fix (they're already fixed!). But it still feels like a 
user-facing regression, and the consistency argument can go both ways: you 
could similarly argue that `dwim-print` should put the result of `frame 
variable` into a convenience variable to keep it consistent with the cases 
where the expression evaluator is used. So the real argument is that most users 
don't need it and it shouldn't be enabled by default. Which is a fine argument 
to make (although it's sad that we don't have data to support it one way or the 
other), but I had to ask to know because the commit description didn't mention 
any reasons at all.


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[Lldb-commits] [PATCH] D145609: [lldb] Change dwim-print to default to disabled persistent results

[Dave Lee via Phabricator via lldb-commits]

kastiglione added a comment.

> Oh, so in the cases where `dwim-print` delegates to frame variable you can't 
> then refer to that result in another `dwim-print` command/other place where 
> you'd like to reference a previously printed value?

If the variable is in scope, you can use the variable. If it's not in scope, 
can you tell me about the workflows that you'd use it in?

> That seems like a significant regression over existing print functionality 
> and compared to gdb. At least for me that'd be annoying/inconvenient to have 
> to think about which kind of printing I'm doing (& have to explicitly use the 
> less stable full expression based printing) when I want to reuse a value.

Our expectation is that for users such as yourself, the solution is to 
customize the `p` alias, or alternatively create a separate alias, like `pr` 
(print w/ result). Does that seem reasonable? My plan is to use `e` for the 
cases where I want persistent results, since `expression` still defaults to 
persisting result variables.

> Got data on that? I'd /guess/ I use it maybe in single digit % of my prints, 
> but probably at least 1%, though no idea if that's representative - even if 
> it is, the inconsistency feels counter to the goals of dwim-print & the 
> convenience provided by gdb's consistent value handling.

Re data: only anecdotal. I expect that those of us who work on lldb represent 
the biggest users of persistent results, but how much is that? You estimate 1%. 
I use it less than that, maybe one out of a thousand (0.01%), but probably 
less. @aprantl has mentioned he's more likely to hit the up arrow and edit a 
previous command than use persistent results, which I can see being true for 
most users.

It's not that the ability is taken away, only that the default is being set to 
match the majority of cases – the 99+% of prints don't need a persistent result.


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[Lldb-commits] [PATCH] D145609: [lldb] Change dwim-print to default to disabled persistent results

[David Blaikie via Phabricator via lldb-commits]

dblaikie added a comment.

> The rationale is: dwim-print doesn't always use expression evaluation, it 
> prefers to use frame variable where possible. In the future it could be 
> expanded, for example to print register as well. Because dwim-print doesn't 
> always use expression, there isn't always a persistent result.

Oh, so in the cases where `dwim-print` delegates to `frame variable` you can't 
then refer to that result in another `dwim-print` command/other place where 
you'd like to reference a previously printed value?

That seems like a significant regression over existing print functionality and 
compared to gdb. At least for me that'd be annoying/inconvenient to have to 
think about which kind of printing I'm doing (& have to explicitly use the less 
stable full expression based printing) when I want to reuse a value.

> To make dwim-print output consistent, and because it's presumed most users 
> don't use persistent results

Got data on that? I'd /guess/ I use it maybe in single digit % of my prints, 
but probably at least 1%, though no idea if that's representative - even if it 
is, the inconsistency feels counter to the goals of dwim-print & the 
convenience provided by gdb's consistent value handling.


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[Lldb-commits] [PATCH] D145609: [lldb] Change dwim-print to default to disabled persistent results

[Adrian Prantl via Phabricator via lldb-commits]

aprantl added a comment.

> breaks basically anything that examines debugger output

I'd be curious to learn about some example you have in mind here.


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[Lldb-commits] [PATCH] D145609: [lldb] Change dwim-print to default to disabled persistent results

[Dave Lee via Phabricator via lldb-commits]

kastiglione added a comment.

> Also `--persistent-result on` can't be passed to print, it only works for me 
> if I run specifically `dwim-print`. Is that intended?

The intension is that for users who want persistent results enabled can do so 
by customizing their `p` or `print` alias, like so:

  command unalias print
  command alias print dwim-print --persistent-result on --



> What was the rationale for this change? It changes the output format of a 
> common command (given that `print` is now an alias for `dwim-print`) and it 
> breaks basically anything that examines debugger output.

Are you using persistent results? If not, how much effort is it to either 1) 
change the tools/code that examine the output to not look for `$\d+`, or 2) use 
a custom `print`/`p` alias? Honest question.

The rationale is: `dwim-print` doesn't always use expression evaluation, it 
prefers to use `frame variable` where possible. In the future it could be 
expanded, for example to print register as well. Because `dwim-print` doesn't 
always use `expression`, there isn't always a persistent result. To make 
`dwim-print` output consistent, and because it's presumed most users don't use 
persistent results, we changed `dwim-print` to default to no persistent 
results. By consistent output, I mean that if a user runs `print someVar` and 
then follows that by running `print someVar.dump()`, it could be confusing if 
the first command doesn't have a persistent result, but the second one does.


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[Lldb-commits] [PATCH] D145609: [lldb] Change dwim-print to default to disabled persistent results

[Jorge Gorbe Moya via Phabricator via lldb-commits]

jgorbe added a comment.

What was the rationale for this change? It changes the output format of a 
common command (given that `print` is now an alias for `dwim-print`) and it 
breaks basically anything that examines debugger output.

Also `--persistent-result on` can't be passed to `print`, it only works for me 
if I run specifically `dwim-print`. Is that intended?


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[Lldb-commits] [PATCH] D145609: [lldb] Change dwim-print to default to disabled persistent results

[Dave Lee via Phabricator via lldb-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG8bad4ae679df: [lldb] Change dwim-print to default to 
disabled persistent results (authored by kastiglione).

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Files:
  lldb/source/Commands/CommandObjectDWIMPrint.cpp
  lldb/source/Commands/CommandObjectExpression.cpp
  lldb/source/Commands/CommandObjectExpression.h
  lldb/test/API/commands/dwim-print/TestDWIMPrint.py

Index: lldb/test/API/commands/dwim-print/TestDWIMPrint.py
===
--- lldb/test/API/commands/dwim-print/TestDWIMPrint.py
+++ lldb/test/API/commands/dwim-print/TestDWIMPrint.py
@@ -16,18 +16,16 @@
 self.ci.HandleCommand(cmd, result)
 return result.GetOutput().rstrip()
 
-VAR_IDENT_RAW = r"(?:\$\d+|\w+) = "
-VAR_IDENT = re.compile(VAR_IDENT_RAW)
+VAR_IDENT = re.compile(r"(?:\$\d+|\w+) = ")
 
-def _mask_persistent_var(self, string: str) -> str:
+def _strip_result_var(self, string: str) -> str:
 """
-Replace persistent result variables (ex '$0', '$1', etc) with a regex
-that matches any persistent result (r'\$\d+'). The returned string can
-be matched against other `expression` results.
+Strip (persistent) result variables (ex '$0 = ', or 'someVar = ', etc).
+
+This allows for using the output of `expression`/`frame variable`, to
+compare it to `dwim-print` output, which disables result variables.
 """
-before, after = self.VAR_IDENT.split(string, maxsplit=1)
-# Support either a frame variable (\w+) or a persistent result (\$\d+).
-return re.escape(before) + self.VAR_IDENT_RAW + re.escape(after)
+return self.VAR_IDENT.subn("", string, 1)[0]
 
 def _expect_cmd(
 self,
@@ -46,19 +44,16 @@
 if actual_cmd == "frame variable":
 resolved_cmd = resolved_cmd.replace(" -- ", " ", 1)
 
-expected_output = self._run_cmd(resolved_cmd)
+resolved_cmd_output = self._run_cmd(resolved_cmd)
+dwim_cmd_output = self._strip_result_var(resolved_cmd_output)
 
 # Verify dwim-print chose the expected command.
 self.runCmd("settings set dwim-print-verbosity full")
-substrs = [f"note: ran `{resolved_cmd}`"]
-patterns = []
-
-if self.VAR_IDENT.search(expected_output):
-patterns.append(self._mask_persistent_var(expected_output))
-else:
-substrs.append(expected_output)
 
-self.expect(dwim_cmd, substrs=substrs, patterns=patterns)
+self.expect(dwim_cmd, substrs=[
+f"note: ran `{resolved_cmd}`",
+dwim_cmd_output,
+])
 
 def test_variables(self):
 """Test dwim-print with variables."""
Index: lldb/source/Commands/CommandObjectExpression.h
===
--- lldb/source/Commands/CommandObjectExpression.h
+++ lldb/source/Commands/CommandObjectExpression.h
@@ -53,7 +53,7 @@
 lldb::LanguageType language;
 LanguageRuntimeDescriptionDisplayVerbosity m_verbosity;
 LazyBool auto_apply_fixits;
-bool suppress_persistent_result;
+LazyBool suppress_persistent_result;
   };
 
   CommandObjectExpression(CommandInterpreter );
Index: lldb/source/Commands/CommandObjectExpression.cpp
===
--- lldb/source/Commands/CommandObjectExpression.cpp
+++ lldb/source/Commands/CommandObjectExpression.cpp
@@ -151,7 +151,7 @@
 bool persist_result =
 OptionArgParser::ToBoolean(option_arg, true, );
 if (success)
-  suppress_persistent_result = !persist_result;
+  suppress_persistent_result = !persist_result ? eLazyBoolYes : eLazyBoolNo;
 else
   error.SetErrorStringWithFormat(
   "could not convert \"%s\" to a boolean value.",
@@ -187,7 +187,7 @@
   auto_apply_fixits = eLazyBoolCalculate;
   top_level = false;
   allow_jit = true;
-  suppress_persistent_result = false;
+  suppress_persistent_result = eLazyBoolCalculate;
 }
 
 llvm::ArrayRef
@@ -202,8 +202,9 @@
   options.SetCoerceToId(display_opts.use_objc);
   // Explicitly disabling persistent results takes precedence over the
   // m_verbosity/use_objc logic.
-  if (suppress_persistent_result)
-options.SetSuppressPersistentResult(true);
+  if (suppress_persistent_result != eLazyBoolCalculate)
+options.SetSuppressPersistentResult(suppress_persistent_result ==
+eLazyBoolYes);
   else if (m_verbosity == eLanguageRuntimeDescriptionDisplayVerbosityCompact)
 options.SetSuppressPersistentResult(display_opts.use_objc);
   options.SetUnwindOnError(unwind_on_error);
Index: lldb/source/Commands/CommandObjectDWIMPrint.cpp
===
--- 

[Lldb-commits] [PATCH] D145609: [lldb] Change dwim-print to default to disabled persistent results

[Dave Lee via Phabricator via lldb-commits]

kastiglione updated this revision to Diff 503515.
kastiglione added a comment.

Cleanup TestDWIMPrint


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Files:
  lldb/source/Commands/CommandObjectDWIMPrint.cpp
  lldb/source/Commands/CommandObjectExpression.cpp
  lldb/source/Commands/CommandObjectExpression.h
  lldb/test/API/commands/dwim-print/TestDWIMPrint.py

Index: lldb/test/API/commands/dwim-print/TestDWIMPrint.py
===
--- lldb/test/API/commands/dwim-print/TestDWIMPrint.py
+++ lldb/test/API/commands/dwim-print/TestDWIMPrint.py
@@ -16,18 +16,16 @@
 self.ci.HandleCommand(cmd, result)
 return result.GetOutput().rstrip()
 
-VAR_IDENT_RAW = r"(?:\$\d+|\w+) = "
-VAR_IDENT = re.compile(VAR_IDENT_RAW)
+VAR_IDENT = re.compile(r"(?:\$\d+|\w+) = ")
 
-def _mask_persistent_var(self, string: str) -> str:
+def _strip_result_var(self, string: str) -> str:
 """
-Replace persistent result variables (ex '$0', '$1', etc) with a regex
-that matches any persistent result (r'\$\d+'). The returned string can
-be matched against other `expression` results.
+Strip (persistent) result variables (ex '$0 = ', or 'someVar = ', etc).
+
+This allows for using the output of `expression`/`frame variable`, to
+compare it to `dwim-print` output, which disables result variables.
 """
-before, after = self.VAR_IDENT.split(string, maxsplit=1)
-# Support either a frame variable (\w+) or a persistent result (\$\d+).
-return re.escape(before) + self.VAR_IDENT_RAW + re.escape(after)
+return self.VAR_IDENT.subn("", string, 1)[0]
 
 def _expect_cmd(
 self,
@@ -46,19 +44,16 @@
 if actual_cmd == "frame variable":
 resolved_cmd = resolved_cmd.replace(" -- ", " ", 1)
 
-expected_output = self._run_cmd(resolved_cmd)
+resolved_cmd_output = self._run_cmd(resolved_cmd)
+dwim_cmd_output = self._strip_result_var(resolved_cmd_output)
 
 # Verify dwim-print chose the expected command.
 self.runCmd("settings set dwim-print-verbosity full")
-substrs = [f"note: ran `{resolved_cmd}`"]
-patterns = []
 
-if self.VAR_IDENT.search(expected_output):
-patterns.append(self._mask_persistent_var(expected_output))
-else:
-substrs.append(expected_output)
-
-self.expect(dwim_cmd, substrs=substrs, patterns=patterns)
+self.expect(dwim_cmd, substrs=[
+f"note: ran `{resolved_cmd}`",
+dwim_cmd_output,
+])
 
 def test_variables(self):
 """Test dwim-print with variables."""
Index: lldb/source/Commands/CommandObjectExpression.h
===
--- lldb/source/Commands/CommandObjectExpression.h
+++ lldb/source/Commands/CommandObjectExpression.h
@@ -53,7 +53,7 @@
 lldb::LanguageType language;
 LanguageRuntimeDescriptionDisplayVerbosity m_verbosity;
 LazyBool auto_apply_fixits;
-bool suppress_persistent_result;
+LazyBool suppress_persistent_result;
   };
 
   CommandObjectExpression(CommandInterpreter );
Index: lldb/source/Commands/CommandObjectExpression.cpp
===
--- lldb/source/Commands/CommandObjectExpression.cpp
+++ lldb/source/Commands/CommandObjectExpression.cpp
@@ -151,7 +151,7 @@
 bool persist_result =
 OptionArgParser::ToBoolean(option_arg, true, );
 if (success)
-  suppress_persistent_result = !persist_result;
+  suppress_persistent_result = !persist_result ? eLazyBoolYes : eLazyBoolNo;
 else
   error.SetErrorStringWithFormat(
   "could not convert \"%s\" to a boolean value.",
@@ -187,7 +187,7 @@
   auto_apply_fixits = eLazyBoolCalculate;
   top_level = false;
   allow_jit = true;
-  suppress_persistent_result = false;
+  suppress_persistent_result = eLazyBoolCalculate;
 }
 
 llvm::ArrayRef
@@ -202,8 +202,9 @@
   options.SetCoerceToId(display_opts.use_objc);
   // Explicitly disabling persistent results takes precedence over the
   // m_verbosity/use_objc logic.
-  if (suppress_persistent_result)
-options.SetSuppressPersistentResult(true);
+  if (suppress_persistent_result != eLazyBoolCalculate)
+options.SetSuppressPersistentResult(suppress_persistent_result ==
+eLazyBoolYes);
   else if (m_verbosity == eLanguageRuntimeDescriptionDisplayVerbosityCompact)
 options.SetSuppressPersistentResult(display_opts.use_objc);
   options.SetUnwindOnError(unwind_on_error);
Index: lldb/source/Commands/CommandObjectDWIMPrint.cpp
===
--- lldb/source/Commands/CommandObjectDWIMPrint.cpp
+++ lldb/source/Commands/CommandObjectDWIMPrint.cpp
@@ 

[Lldb-commits] [PATCH] D145609: [lldb] Change dwim-print to default to disabled persistent results

[Dave Lee via Phabricator via lldb-commits]

kastiglione created this revision.
kastiglione added reviewers: aprantl, jingham.
Herald added a project: All.
kastiglione requested review of this revision.
Herald added a project: LLDB.
Herald added a subscriber: lldb-commits.

Change `dwim-print` to now disable persistent results by default, unless 
requested by
the user with the `--persistent-result` flag.

Ex:

  (lldb) dwim-print 1 + 1
  (int) 2
  (lldb) dwim-print --persistent-result on -- 1 + 1
  (int) $0 = 2

Users who wish to enable persistent results can make and use an alias that 
includes
`--persistent-result on`.


Repository:
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Files:
  lldb/source/Commands/CommandObjectDWIMPrint.cpp
  lldb/source/Commands/CommandObjectExpression.cpp
  lldb/source/Commands/CommandObjectExpression.h
  lldb/test/API/commands/dwim-print/TestDWIMPrint.py

Index: lldb/test/API/commands/dwim-print/TestDWIMPrint.py
===
--- lldb/test/API/commands/dwim-print/TestDWIMPrint.py
+++ lldb/test/API/commands/dwim-print/TestDWIMPrint.py
@@ -16,8 +16,7 @@
 self.ci.HandleCommand(cmd, result)
 return result.GetOutput().rstrip()
 
-VAR_IDENT_RAW = r"(?:\$\d+|\w+) = "
-VAR_IDENT = re.compile(VAR_IDENT_RAW)
+VAR_IDENT = re.compile(r"(?:\$\d+|\w+) = ")
 
 def _mask_persistent_var(self, string: str) -> str:
 """
@@ -26,8 +25,7 @@
 be matched against other `expression` results.
 """
 before, after = self.VAR_IDENT.split(string, maxsplit=1)
-# Support either a frame variable (\w+) or a persistent result (\$\d+).
-return re.escape(before) + self.VAR_IDENT_RAW + re.escape(after)
+return before + after
 
 def _expect_cmd(
 self,
@@ -51,14 +49,13 @@
 # Verify dwim-print chose the expected command.
 self.runCmd("settings set dwim-print-verbosity full")
 substrs = [f"note: ran `{resolved_cmd}`"]
-patterns = []
 
 if self.VAR_IDENT.search(expected_output):
-patterns.append(self._mask_persistent_var(expected_output))
+substrs.append(self._mask_persistent_var(expected_output))
 else:
 substrs.append(expected_output)
 
-self.expect(dwim_cmd, substrs=substrs, patterns=patterns)
+self.expect(dwim_cmd, substrs=substrs)
 
 def test_variables(self):
 """Test dwim-print with variables."""
Index: lldb/source/Commands/CommandObjectExpression.h
===
--- lldb/source/Commands/CommandObjectExpression.h
+++ lldb/source/Commands/CommandObjectExpression.h
@@ -53,7 +53,7 @@
 lldb::LanguageType language;
 LanguageRuntimeDescriptionDisplayVerbosity m_verbosity;
 LazyBool auto_apply_fixits;
-bool suppress_persistent_result;
+LazyBool suppress_persistent_result;
   };
 
   CommandObjectExpression(CommandInterpreter );
Index: lldb/source/Commands/CommandObjectExpression.cpp
===
--- lldb/source/Commands/CommandObjectExpression.cpp
+++ lldb/source/Commands/CommandObjectExpression.cpp
@@ -151,7 +151,7 @@
 bool persist_result =
 OptionArgParser::ToBoolean(option_arg, true, );
 if (success)
-  suppress_persistent_result = !persist_result;
+  suppress_persistent_result = !persist_result ? eLazyBoolYes : eLazyBoolNo;
 else
   error.SetErrorStringWithFormat(
   "could not convert \"%s\" to a boolean value.",
@@ -187,7 +187,7 @@
   auto_apply_fixits = eLazyBoolCalculate;
   top_level = false;
   allow_jit = true;
-  suppress_persistent_result = false;
+  suppress_persistent_result = eLazyBoolCalculate;
 }
 
 llvm::ArrayRef
@@ -202,8 +202,9 @@
   options.SetCoerceToId(display_opts.use_objc);
   // Explicitly disabling persistent results takes precedence over the
   // m_verbosity/use_objc logic.
-  if (suppress_persistent_result)
-options.SetSuppressPersistentResult(true);
+  if (suppress_persistent_result != eLazyBoolCalculate)
+options.SetSuppressPersistentResult(suppress_persistent_result ==
+eLazyBoolYes);
   else if (m_verbosity == eLanguageRuntimeDescriptionDisplayVerbosityCompact)
 options.SetSuppressPersistentResult(display_opts.use_objc);
   options.SetUnwindOnError(unwind_on_error);
Index: lldb/source/Commands/CommandObjectDWIMPrint.cpp
===
--- lldb/source/Commands/CommandObjectDWIMPrint.cpp
+++ lldb/source/Commands/CommandObjectDWIMPrint.cpp
@@ -71,6 +71,10 @@
 return false;
   }
 
+  // If the user has not specified, default to disabling persistent results.
+  if (m_expr_options.suppress_persistent_result == eLazyBoolCalculate)
+m_expr_options.suppress_persistent_result = eLazyBoolYes;
+
   auto verbosity = GetDebugger().GetDWIMPrintVerbosity();
 
   Target *target_ptr =