[LLDB] no member named 'id' in namespace '$__lldb_local_vars'

[wingfiring]

Description:

If a vaiable named "id", it can't be referenced by command p or expr, and the error message was

error: expression failed to parse:
error: <lldb wrapper prefix>:45:31: no member named 'id' in namespace '$__lldb_local_vars'
    using $__lldb_local_vars::id;
          ~~~~~~~~~~~~~~~~~~~~^
warning: <user expression 1>:1:1: declaration does not declare anything
id
^~

Environment

lldb version: lldb-1400.0.38.17
Apple clang version 14.0.0 (clang-1400.0.29.202)
OS: MacOS 12.6.7 (21G651)
Processor: 3.3 GHz Quad-Core Intel Core i5

Reproduce steps

With code

int main(int argc, char**){
    int i = argc;
    int id = argc;
    return i - id ;
}

build command:
clang++ a.cpp -g

Steps:

$lldb ./a.out
(lldb) b main
(lldb) r aaa
(lldb) n
(lldb) n
(lldb) p i
(int) $0 = 2
(lldb) p id
error: expression failed to parse:
error: <lldb wrapper prefix>:45:31: no member named 'id' in namespace '$__lldb_local_vars'
    using $__lldb_local_vars::id;
          ~~~~~~~~~~~~~~~~~~~~^
warning: <user expression 1>:1:1: declaration does not declare anything
id
^~

[llvmbot]

@llvm/issue-subscribers-lldb

Author: Sun,Chaoyang (wingfiring)

## Description: If a vaiable named "id", it can't be referenced by command `p` or `expr`, and the error message was ``` error: expression failed to parse: error: <lldb wrapper prefix>:45:31: no member named 'id' in namespace '$__lldb_local_vars' using $__lldb_local_vars::id; ~~~~~~~~~~~~~~~~~~~~^ warning: <user expression 1>:1:1: declaration does not declare anything id ^~ ``` ### Environment lldb version: lldb-1400.0.38.17 Apple clang version 14.0.0 (clang-1400.0.29.202) OS: MacOS 12.6.7 (21G651) Processor: 3.3 GHz Quad-Core Intel Core i5

Reproduce steps

With code

int main(int argc, char**){
    int i = argc;
    int id = argc;
    return i - id ;
}

build command:
clang++ a.cpp -g

Steps:

$lldb ./a.out
(lldb) b main
(lldb) r aaa
(lldb) n
(lldb) n
(lldb) p i
(int) $0 = 2
(lldb) p id
error: expression failed to parse:
error: <lldb wrapper prefix>:45:31: no member named 'id' in namespace '$__lldb_local_vars'
    using $__lldb_local_vars::id;
          ~~~~~~~~~~~~~~~~~~~~^
warning: <user expression 1>:1:1: declaration does not declare anything
id
^~

[Michael137]

Yup, and the same is true for Class. This is determined here:

bool ClangASTSource::IgnoreName(const ConstString name,
                                bool ignore_all_dollar_names) {
  static const ConstString id_name("id");
  static const ConstString Class_name("Class");

This was first introduced in 46198ff8249c28d396b01083ed7d109c8bd5229e:

Updated LLVM/Clang to pull in a fix for Objective-C
interfaces.  This allows us to pull in Objective-C
method types on demand, which is also now implemented.

Also added a minor fix to prevent multiple-definition
errors for "Class" and "id".

It's unfortunate that this also affects non-Objective-C expressions.

This is only true for the expression evaluator though, so v id should work fine. In more recent versions of LLDB p is aliased to dwim-print, which would've run v id.

[dlongnecke-cray]

I'm experiencing this issue as well. Really impeding some of my work because I cannot evaluate expressions:

p id.parentSymbolId(context)
error: expression failed to parse:
error: <lldb wrapper prefix>:46:27: no member named 'id' in namespace '$__lldb_local_vars'
using $__lldb_local_vars::id;
      ~~~~~~~~~~~~~~~~~~~~^
error: <user expression 0>:1:3: cannot use dot operator on a type
id.parentSymbolId(context)

I'm using lldb version 16.0.6.

[Michael137]

@clayborg do you remember why this special IgnoreName for id and Class was necessary back when it was introduced in 46198ff8249c28d396b01083ed7d109c8bd5229e? The test-suite passes for me on Darwin without that logic. It'd be unfortunate if we couldn't evaluate these names in pure C++ code