8184b252cd
This patch adds support for evaluating expressions which reference a captured `this` from within the context of a C++ lambda expression. Currently LLDB doesn't provide Clang with enough information to determine that we're inside a lambda expression and are allowed to access variables on a captured `this`; instead Clang simply fails to parse the expression. There are two problems to solve here: 1. Make sure `clang::Sema` doesn't reject the expression due to an illegal member access. 2. Materialize all the captured variables/member variables required to evaluate the expression. To address (1), we currently import the outer structure's AST context onto `$__lldb_class`, making the `contextClass` and the `NamingClass` match, a requirement by `clang::Sema::BuildPossibleImplicitMemberExpr`. To address (2), we inject all captured variables as locals into the expression source code. **Testing** * Added API test
125 lines
5.6 KiB
Python
125 lines
5.6 KiB
Python
""" Test that evaluating expressions from within C++ lambdas works
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Particularly, we test the case of capturing "this" and
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using members of the captured object in expression evaluation
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while we're on a breakpoint inside a lambda.
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"""
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import lldb
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from lldbsuite.test.lldbtest import *
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class ExprInsideLambdaTestCase(TestBase):
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mydir = TestBase.compute_mydir(__file__)
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def expectExprError(self, expr : str, expected : str):
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frame = self.thread.GetFrameAtIndex(0)
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value = frame.EvaluateExpression(expr)
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errmsg = value.GetError().GetCString()
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self.assertIn(expected, errmsg)
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def test_expr_inside_lambda(self):
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"""Test that lldb evaluating expressions inside lambda expressions works correctly."""
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self.build()
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(target, process, self.thread, bkpt) = \
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lldbutil.run_to_source_breakpoint(self, "break here", lldb.SBFileSpec("main.cpp"))
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# Inside 'Foo::method'
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# Check access to captured 'this'
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self.expect_expr("class_var", result_type="int", result_value="109")
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self.expect_expr("this->class_var", result_type="int", result_value="109")
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# Check that captured shadowed variables take preference over the
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# corresponding member variable
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self.expect_expr("shadowed", result_type="int", result_value="5")
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self.expect_expr("this->shadowed", result_type="int", result_value="-137")
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# Check access to local captures
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self.expect_expr("local_var", result_type="int", result_value="137")
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self.expect_expr("*class_ptr", result_type="int", result_value="137")
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# Check access to base class variables
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self.expect_expr("base_var", result_type="int", result_value="14")
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self.expect_expr("base_base_var", result_type="int", result_value="11")
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# Check access to global variable
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self.expect_expr("global_var", result_type="int", result_value="-5")
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# Check access to multiple captures/member variables
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self.expect_expr("(shadowed + this->shadowed) * (base_base_var + local_var - class_var)",
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result_type="int", result_value="-5148")
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# Check base-class function call
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self.expect_expr("baz_virt()", result_type="int", result_value="2")
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self.expect_expr("base_var", result_type="int", result_value="14")
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self.expect_expr("this->shadowed", result_type="int", result_value="-1")
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# 'p this' should yield 'struct Foo*'
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frame = self.thread.GetFrameAtIndex(0)
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outer_class_addr = frame.GetValueForVariablePath("this->this")
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self.expect_expr("this", result_value=outer_class_addr.GetValue())
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lldbutil.continue_to_breakpoint(process, bkpt)
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# Inside 'nested_lambda'
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# Check access to captured 'this'. Should still be 'struct Foo*'
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self.expect_expr("class_var", result_type="int", result_value="109")
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self.expect_expr("global_var", result_type="int", result_value="-5")
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self.expect_expr("this", result_value=outer_class_addr.GetValue())
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# Check access to captures
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self.expect_expr("lambda_local_var", result_type="int", result_value="5")
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self.expect_expr("local_var", result_type="int", result_value="137")
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# Check access to variable in previous frame which we didn't capture
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self.expectExprError("local_var_copy", "use of undeclared identifier")
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lldbutil.continue_to_breakpoint(process, bkpt)
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# By-ref mutates source variable
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self.expect_expr("lambda_local_var", result_type="int", result_value="0")
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# By-value doesn't mutate source variable
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self.expect_expr("local_var_copy", result_type="int", result_value="136")
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self.expect_expr("local_var", result_type="int", result_value="137")
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lldbutil.continue_to_breakpoint(process, bkpt)
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# Inside 'LocalLambdaClass::inner_method'
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# Check access to captured 'this'
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self.expect_expr("lambda_class_local", result_type="int", result_value="-12345")
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self.expect_expr("this->lambda_class_local", result_type="int", result_value="-12345")
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self.expect_expr("outer_ptr->class_var", result_type="int", result_value="109")
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# 'p this' should yield 'struct LocalLambdaClass*'
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frame = self.thread.GetFrameAtIndex(0)
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local_class_addr = frame.GetValueForVariablePath("this->this")
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self.assertNotEqual(local_class_addr, outer_class_addr)
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self.expect_expr("this", result_value=local_class_addr.GetValue())
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# Can still access global variable
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self.expect_expr("global_var", result_type="int", result_value="-5")
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# Check access to outer top-level structure's members
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self.expectExprError("class_var", ("use of non-static data member"
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" 'class_var' of 'Foo' from nested type"))
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self.expectExprError("base_var", ("use of non-static data member"
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" 'base_var'"))
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self.expectExprError("local_var", ("use of non-static data member 'local_var'"
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" of '' from nested type 'LocalLambdaClass'"))
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# Inside non_capturing_method
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lldbutil.continue_to_breakpoint(process, bkpt)
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self.expect_expr("local", result_type="int", result_value="5")
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self.expect_expr("local2", result_type="int", result_value="10")
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self.expect_expr("local2 * local", result_type="int", result_value="50")
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self.expectExprError("class_var", ("use of non-static data member"
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" 'class_var' of 'Foo' from nested type"))
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