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[lldb-dap] Improving 'variables' hover requests. #146773

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[lldb-dap] Improving 'variables' hover requests. #146773

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[lldb-dap] Improving 'variables' hover requests.
ashgti Jul 2, 2025
3da6fd0
Only trim leading '&*' characters on context='hover' and ensure we on…
ashgti Jul 7, 2025
df06997
Remove the change to when we allow evaluation. Splitting into its own…
ashgti Jul 7, 2025
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2 changes: 1 addition & 1 deletion lldb/test/API/tools/lldb-dap/memory/TestDAP_memory.py
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Original file line number Diff line number Diff line change
Expand Up @@ -92,7 +92,7 @@ def test_readMemory(self):
)
self.continue_to_next_stop()

ptr_deref = self.dap_server.request_evaluate("*rawptr")["body"]
ptr_deref = self.dap_server.request_evaluate("*rawptr", context="repl")["body"]
memref = ptr_deref["memoryReference"]

# We can read the complete string
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10 changes: 10 additions & 0 deletions lldb/tools/lldb-dap/Handler/EvaluateRequestHandler.cpp
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Expand Up @@ -181,7 +181,17 @@ void EvaluateRequestHandler::operator()(
expression = dap.last_nonempty_var_expression;
else
dap.last_nonempty_var_expression = expression;
} else {
// If this isn't a REPL context, trim leading pointer/reference characters
// to ensure we return the actual value of the expression.
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doesn't this also trigger in way too many other contexts? E.g., also in the watch panel? I think in the watch panel a *x should actually dereference x

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@jimingham jimingham Jul 4, 2025 •
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Since people have to voluntarily put something in a watch panel, then in that case we should even run it as an expression. If somebody actually puts i++ in a watch window, presumably they meant for it to increment every time they stepped.
We had a silly bug in gdbtk way back in the day where we if you moused over a selection we would run the selection as an expression. But lots of people seem to select expressions so that they can focus on just the part they selected. As you can imagine, that went poorly.
The main thing - for me - is to always have running expressions be a distinct gesture.

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I agree that we shouldn't run evaluate expressions like i++ in a watch context.

I can fix that as well in this change as well. We're trying the expression with frame.EvaluateExpression if its not 'hover' but that should really be only used if 'context' == 'repl'.

I also updated this to only trim leading &* for 'hover' specifically since watching *x should be supported.

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I actually removed that part of from this PR and I'll move it into its own PR since it has some other implications.

// This can come up if you hover over a pointer or reference declaration
// like 'MyType *foo;' or `void fn(std::string &arg)`, which results in
// the hover request sending '*foo' or `&arg`. When we're not in the REPL,
// we should trim these characters to get to the actual variable, which
// should have the proper type encoded by the compiler.
expression = llvm::StringRef(expression).ltrim("*&").str();
}

// Always try to get the answer from the local variables if possible. If
// this fails, then if the context is not "hover", actually evaluate an
// expression using the expression parser.
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