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[lldb][Expression] Emit hint to use --c++-ignore-context-qualifiers #177927

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Merged
Michael137 merged 4 commits into from
Feb 5, 2026
Merged

[lldb][Expression] Emit hint to use --c++-ignore-context-qualifiers #177927

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03aba9f
[lldb][Expression] Emit hint to use --ignore-const-context
Michael137 Jan 23, 2026
37fce7a
fixup! rename option
Michael137 Jan 30, 2026
30ff57c
fixup! cpp -> c++
Michael137 Feb 4, 2026
6d8ec2b
fixup! add expression text to hint
Michael137 Feb 5, 2026
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10 changes: 10 additions & 0 deletions lldb/include/lldb/Expression/UserExpression.h
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Original file line number Diff line number Diff line change
Expand Up @@ -313,6 +313,16 @@ class UserExpression : public Expression {
lldb::ProcessSP &process_sp,
lldb::StackFrameSP &frame_sp);

/// Called by expression evaluator when a parse error occurs. Gives this
/// UserExpression object a chance to inspect and adjust the error diagnostics
/// contained in the specified \c diagnostic_manager.
///
/// \param[in,out] diagnostic_manager DiagnosticManager manager holding the
/// parse error diagnostics. This function may mutate the diagnostics.
///
virtual void
FixupParseErrorDiagnostics(DiagnosticManager &diagnostic_manager) const {}

/// The address the process is stopped in.
Address m_address;
/// The text of the expression, as typed by the user.
Expand Down
3 changes: 3 additions & 0 deletions lldb/source/Expression/UserExpression.cpp
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Expand Up @@ -323,6 +323,9 @@ UserExpression::Evaluate(ExecutionContext &exe_ctx,
}

if (!parse_success) {
if (user_expression_sp)
user_expression_sp->FixupParseErrorDiagnostics(diagnostic_manager);

if (target->GetEnableNotifyAboutFixIts() && fixed_expression &&
!fixed_expression->empty()) {
std::string fixit =
Expand Down
42 changes: 42 additions & 0 deletions lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp
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Expand Up @@ -27,6 +27,7 @@
#include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
#include "lldb/Core/Debugger.h"
#include "lldb/Core/Module.h"
#include "lldb/Expression/DiagnosticManager.h"
#include "lldb/Expression/ExpressionSourceCode.h"
#include "lldb/Expression/IRExecutionUnit.h"
#include "lldb/Expression/IRInterpreter.h"
Expand Down Expand Up @@ -55,6 +56,7 @@
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"

#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/ScopeExit.h"
#include "llvm/BinaryFormat/Dwarf.h"

Expand Down Expand Up @@ -946,6 +948,46 @@ lldb::ExpressionVariableSP ClangUserExpression::GetResultAfterDematerialization(
return m_result_delegate.GetVariable();
}

void ClangUserExpression::FixupParseErrorDiagnostics(
DiagnosticManager &diagnostic_manager) const {
const bool is_fixable_cvr_error = llvm::any_of(
diagnostic_manager.Diagnostics(),
[](std::unique_ptr<Diagnostic> const &diag) {
switch (diag->GetCompilerID()) {
case clang::diag::err_member_function_call_bad_cvr:
return true;
case clang::diag::err_typecheck_assign_const:
// FIXME: can we split this particular error into a separate
// diagnostic ID so we don't need to scan the error message?
return diag->GetDetail().message.find(
"within const member function") != std::string::npos;
default:
return false;
}
});

// Nothing to report.
if (!is_fixable_cvr_error)
return;

// If the user already tried ignoring function qualifiers but
// the expression still failed, we don't want to suggest the hint again.
if (m_options.GetCppIgnoreContextQualifiers()) {
// Hard to prove that we don't get here so don't emit a diagnostic n
// non-asserts builds. But we do want a signal in asserts builds.
assert(false &&
"CppIgnoreContextQualifiers didn't resolve compiler diagnostic.");
return;
}

diagnostic_manager.Printf(
lldb::eSeverityInfo,
"Possibly trying to mutate object in a const context. Try "
"running the expression with: expression --c++-ignore-context-qualifiers "
"-- %s",
!m_fixed_text.empty() ? m_fixed_text.c_str() : m_expr_text.c_str());
}

char ClangUserExpression::ClangUserExpressionHelper::ID;

void ClangUserExpression::ClangUserExpressionHelper::ResetDeclMap(
Expand Down
4 changes: 4 additions & 0 deletions lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.h
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Expand Up @@ -179,6 +179,10 @@ class ClangUserExpression : public LLVMUserExpression {

llvm::StringRef GetFilename() const { return m_filename; }

protected:
void FixupParseErrorDiagnostics(
DiagnosticManager &diagnostic_manager) const override;

private:
/// Populate m_in_cplusplus_method and m_in_objectivec_method based on the
/// environment.
Expand Down
24 changes: 14 additions & 10 deletions lldb/test/API/lang/cpp/expression-context-qualifiers/const_method/TestExprInConstMethod.py
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Expand Up @@ -16,15 +16,16 @@ def test(self):
"expression m_const_mem = 2.0",
error=True,
substrs=[
"cannot assign to non-static data member",
"with const-qualified type",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
matching=False,
)
self.expect(
"expression m_mem = 2.0",
error=True,
substrs=[
"cannot assign to non-static data member within const member function"
"cannot assign to non-static data member within const member function",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
)
self.expect_expr("m_mem", result_value="-2")
Expand Down Expand Up @@ -60,7 +61,8 @@ def test(self):
"expression x = 7.0",
error=True,
substrs=[
"cannot assign to non-static data member within const member function"
"cannot assign to non-static data member within const member function",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
)
self.expect_expr("x", result_value="2")
Expand All @@ -87,15 +89,16 @@ def test(self):
"expression m_const_mem = 2.0",
error=True,
substrs=[
"cannot assign to non-static data member",
"with const-qualified type",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
matching=False,
)
self.expect(
"expression m_mem = 2.0",
error=True,
substrs=[
"cannot assign to non-static data member within const member function"
"cannot assign to non-static data member within const member function",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
)
self.expect_expr("m_mem", result_value="-2")
Expand All @@ -117,15 +120,16 @@ def test(self):
"expression m_const_mem = 2.0",
error=True,
substrs=[
"cannot assign to non-static data member",
"with const-qualified type",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
matching=False,
)
self.expect(
"expression m_mem = 2.0",
error=True,
substrs=[
"cannot assign to non-static data member within const member function"
"cannot assign to non-static data member within const member function",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
)
self.expect_expr("m_mem", result_value="-1")
Expand Down
14 changes: 12 additions & 2 deletions .../cpp/expression-context-qualifiers/const_volatile_method/TestExprInConstVolatileMethod.py
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Expand Up @@ -17,7 +17,11 @@ def test(self):
self.expect(
"expression volatile_method()",
error=True,
substrs=["has type 'const Foo'", "but function is not marked const"],
substrs=[
"has type 'const Foo'",
"but function is not marked const",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
)

options = lldb.SBExpressionOptions()
Expand All @@ -41,7 +45,11 @@ def test(self):
self.expect(
"expression const_method()",
error=True,
substrs=["has type 'volatile Foo'", "but function is not marked volatile"],
substrs=[
"has type 'volatile Foo'",
"but function is not marked volatile",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
)
self.expect_expr("volatile_method()")

Expand All @@ -65,6 +73,7 @@ def test(self):
substrs=[
"has type 'const volatile Foo'",
"but function is not marked const or volatile",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
)
self.expect(
Expand All @@ -73,6 +82,7 @@ def test(self):
substrs=[
"has type 'const volatile Foo'",
"but function is not marked const or volatile",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
)

Expand Down
29 changes: 28 additions & 1 deletion lldb/test/API/lang/cpp/expression-context-qualifiers/fixit/TestExprInConstMethodWithFixit.py
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Expand Up @@ -17,10 +17,12 @@ def test(self):
substrs=[
"member reference type 'const Bar' is not a pointer",
"but function is not marked const",
"Possibly trying to mutate object in a const context. Try running the expression with",
"expression --c++-ignore-context-qualifiers -- m_bar.method()",
],
)

# Two fix-its
# Two fix-its...
self.expect(
"expression -- m_bar->method() + m_bar->method()",
error=True,
Expand All @@ -32,11 +34,36 @@ def test(self):
],
)

# ...only emit a single hint.
self.assertEqual(
self.res.GetError().count(
"Possibly trying to mutate object in a const context."
),
1,
)

self.expect(
"expression -Q -- m_bar->method()",
error=True,
substrs=["Evaluated this expression after applying Fix-It(s):"],
)

self.expect(
"expression m_bar->method() + blah",
error=True,
substrs=[
"member reference type 'const Bar' is not a pointer",
"but function is not marked const",
"Possibly trying to mutate object in a const context. Try running the expression with",
"expression --c++-ignore-context-qualifiers -- m_bar.method() + blah",
],
)

self.expect(
"expression -Q -- m_bar->method() + blah",
error=True,
substrs=[
"Possibly trying to mutate object in a const context. Try running the expression with",
],
matching=False,
)
3 changes: 2 additions & 1 deletion ...t/API/lang/cpp/expression-context-qualifiers/non_const_method/TestExprInNonConstMethod.py
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Expand Up @@ -32,7 +32,8 @@ def test(self):
"expression x = 7.0",
error=True,
substrs=[
"cannot assign to non-static data member within const member function"
"cannot assign to non-static data member within const member function",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
)

Expand Down
12 changes: 8 additions & 4 deletions .../cpp/expression-context-qualifiers/template_const_method/TestExprInTemplateConstMethod.py
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Expand Up @@ -24,7 +24,8 @@ def test(self):
"expression m_mem = 2.0",
error=True,
substrs=[
"cannot assign to non-static data member within const member function"
"cannot assign to non-static data member within const member function",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
)
self.expect_expr("((Foo*)this)->bar()", result_type="double", result_value="5")
Expand All @@ -44,7 +45,8 @@ def test(self):
"expression x = 7.0",
error=True,
substrs=[
"cannot assign to non-static data member within const member function"
"cannot assign to non-static data member within const member function",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
)
self.expect_expr("x = -7.0; x", options=options, result_value="-7")
Expand Down Expand Up @@ -77,7 +79,8 @@ def test(self):
"expression m_mem = 2.0",
error=True,
substrs=[
"cannot assign to non-static data member within const member function"
"cannot assign to non-static data member within const member function",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
)
self.expect_expr("m_mem", result_value="-2")
Expand Down Expand Up @@ -105,7 +108,8 @@ def test(self):
"expression m_mem = 2.0",
error=True,
substrs=[
"cannot assign to non-static data member within const member function"
"cannot assign to non-static data member within const member function",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
],
)
self.expect_expr("m_mem = -11.0; m_mem", options=options, result_value="-11")
4 changes: 3 additions & 1 deletion ...pression-context-qualifiers/template_non_const_method/TestExprInTemplateNonConstMethod.py
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Expand Up @@ -32,7 +32,9 @@ def test(self):
"expression x = 7.0",
error=True,
substrs=[
"cannot assign to non-static data member within const member function"
"cannot assign to non-static data member within const member function",
"note: Possibly trying to mutate object in a const context. Try running the expression with",
"expression --c++-ignore-context-qualifiers -- x = 7.0",
],
)

Expand Down
3 changes: 2 additions & 1 deletion lldb/test/API/lang/cpp/this/TestCPPThis.py
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Expand Up @@ -42,7 +42,8 @@ def test_with_run_command(self):
"expression -- m_a = 2",
error=True,
substrs=[
"cannot assign to non-static data member within const member function"
"cannot assign to non-static data member within const member function",
"Possibly trying to mutate object in a const context. Try running the expression with: expression --c++-ignore-context-qualifiers -- m_a = 2",
],
)

Expand Down
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