lldb/test/API/commands/expression/expr_inside_lambda/TestExprInsideLambdas.py

   1 """ Test that evaluating expressions from within C++ lambdas works
   2     Particularly, we test the case of capturing "this" and
   3     using members of the captured object in expression evaluation
   4     while we're on a breakpoint inside a lambda.
   5 """
   6
   7
   8 import lldb
   9 from lldbsuite.test.lldbtest import *
  10
  11
  12 class ExprInsideLambdaTestCase(TestBase):
  13     def expectExprError(self, expr: str, expected: str):
  14         frame = self.thread.GetFrameAtIndex(0)
  15         value = frame.EvaluateExpression(expr)
  16         errmsg = value.GetError().GetCString()
  17         self.assertIn(expected, errmsg)
  18
  19     def test_expr_inside_lambda(self):
  20         """Test that lldb evaluating expressions inside lambda expressions works correctly."""
  21         self.build()
  22         (target, process, self.thread, bkpt) = lldbutil.run_to_source_breakpoint(
  23             self, "break here", lldb.SBFileSpec("main.cpp")
  24         )
  25
  26         # Inside 'Foo::method'
  27
  28         # Check access to captured 'this'
  29         self.expect_expr("class_var", result_type="int", result_value="109")
  30         self.expect_expr("this->class_var", result_type="int", result_value="109")
  31
  32         # Check that captured shadowed variables take preference over the
  33         # corresponding member variable
  34         self.expect_expr("shadowed", result_type="int", result_value="5")
  35         self.expect_expr("this->shadowed", result_type="int", result_value="-137")
  36
  37         # Check access to local captures
  38         self.expect_expr("local_var", result_type="int", result_value="137")
  39         self.expect_expr("*class_ptr", result_type="int", result_value="137")
  40
  41         # Check access to base class variables
  42         self.expect_expr("base_var", result_type="int", result_value="14")
  43         self.expect_expr("base_base_var", result_type="int", result_value="11")
  44
  45         # Check access to global variable
  46         self.expect_expr("global_var", result_type="int", result_value="-5")
  47
  48         # Check access to multiple captures/member variables
  49         self.expect_expr(
  50             "(shadowed + this->shadowed) * (base_base_var + local_var - class_var)",
  51             result_type="int",
  52             result_value="-5148",
  53         )
  54
  55         # Check base-class function call
  56         self.expect_expr("baz_virt()", result_type="int", result_value="2")
  57         self.expect_expr("base_var", result_type="int", result_value="14")
  58         self.expect_expr("this->shadowed", result_type="int", result_value="-1")
  59
  60         # 'p this' should yield 'struct Foo*'
  61         frame = self.thread.GetFrameAtIndex(0)
  62         outer_class_addr = frame.GetValueForVariablePath("this->this")
  63         self.expect_expr("this", result_value=outer_class_addr.GetValue())
  64
  65         lldbutil.continue_to_breakpoint(process, bkpt)
  66
  67         # Inside 'nested_lambda'
  68
  69         # Check access to captured 'this'. Should still be 'struct Foo*'
  70         self.expect_expr("class_var", result_type="int", result_value="109")
  71         self.expect_expr("global_var", result_type="int", result_value="-5")
  72         self.expect_expr("this", result_value=outer_class_addr.GetValue())
  73
  74         # Check access to captures
  75         self.expect_expr("lambda_local_var", result_type="int", result_value="5")
  76         self.expect_expr("local_var", result_type="int", result_value="137")
  77
  78         # Check access to variable in previous frame which we didn't capture
  79         self.expectExprError("local_var_copy", "use of undeclared identifier")
  80
  81         lldbutil.continue_to_breakpoint(process, bkpt)
  82
  83         # By-ref mutates source variable
  84         self.expect_expr("lambda_local_var", result_type="int", result_value="0")
  85
  86         # By-value doesn't mutate source variable
  87         self.expect_expr("local_var_copy", result_type="int", result_value="136")
  88         self.expect_expr("local_var", result_type="int", result_value="137")
  89
  90         lldbutil.continue_to_breakpoint(process, bkpt)
  91
  92         # Inside 'LocalLambdaClass::inner_method'
  93
  94         # Check access to captured 'this'
  95         self.expect_expr("lambda_class_local", result_type="int", result_value="-12345")
  96         self.expect_expr(
  97             "this->lambda_class_local", result_type="int", result_value="-12345"
  98         )
  99         self.expect_expr("outer_ptr->class_var", result_type="int", result_value="109")
 100
 101         # 'p this' should yield 'struct LocalLambdaClass*'
 102         frame = self.thread.GetFrameAtIndex(0)
 103         local_class_addr = frame.GetValueForVariablePath("this->this")
 104         self.assertNotEqual(local_class_addr, outer_class_addr)
 105         self.expect_expr("this", result_value=local_class_addr.GetValue())
 106
 107         # Can still access global variable
 108         self.expect_expr("global_var", result_type="int", result_value="-5")
 109
 110         # Check access to outer top-level structure's members
 111         self.expectExprError(
 112             "class_var",
 113             ("use of non-static data member" " 'class_var' of 'Foo' from nested type"),
 114         )
 115
 116         self.expectExprError(
 117             "base_var", ("use of non-static data member" " 'base_var'")
 118         )
 119
 120         self.expectExprError(
 121             "local_var",
 122             (
 123                 "use of non-static data member 'local_var'"
 124                 " of '(unnamed class)' from nested type 'LocalLambdaClass'"
 125             ),
 126         )
 127
 128         # Inside non_capturing_method
 129         lldbutil.continue_to_breakpoint(process, bkpt)
 130         self.expect_expr("local", result_type="int", result_value="5")
 131         self.expect_expr("local2", result_type="int", result_value="10")
 132         self.expect_expr("local2 * local", result_type="int", result_value="50")
 133
 134         self.expectExprError(
 135             "class_var",
 136             ("use of non-static data member" " 'class_var' of 'Foo' from nested type"),
 137         )