[Bug 2059856] Re: [SRU] gdb 10.0 fails to examine any global variables in D programs

[Zixing Liu]

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** Tags removed: verification-needed verification-needed-jammy
** Tags added: verification-done verification-done-jammy

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Title:
  [SRU] gdb 10.0 fails to examine any global variables in D programs

Status in gdb:
  Fix Released
Status in gdb package in Ubuntu:
  Fix Released
Status in gdb source package in Jammy:
  Fix Committed
Status in gdb source package in Noble:
  Fix Released
Status in gdb source package in Oracular:
  Fix Released
Status in gdb source package in Plucky:
  Fix Released

Bug description:
  [Impact]

   * GDB 10.0 introduced a regression where it cannot inspect any global variables in any D programs compiled by any D compiler.
   * LDC2 and GDC upstream stated Focal does not have such a problem and stuck to this release for their test images.

  [Test Plan]

  Considering the following D program:

  ```
  module t;

  class uv {
      int i;
  }

  __gshared uv i;
  int main() {
      i = new uv();
      return 0; // #break
  }
  ```

  If you build it using `gdc -g -O0 t.d -o t` or `ldc2 -o t.o t.d -g`,
  run the GDB using the following commands ...

  ```
  b t.d:10
  p t.i
  ```

  ... you will notice GDB will complain that "'t.i' has unknown type;
  cast it to its declared type."

  [Where problems could occur]

    * The fix consists of a single line change to the demangler. The worst-case scenario would be breaking the demangling functionality of other programming languages. However, the newer D ABI uses a symbol mangling scheme that is very difficult to confuse with other programming languages.
    * Incorrect symbol de-mangling may also cause user confusion. However, the patch fixed a fundamental usability issue.

  [Other Info]

    * Initial discussion in the LDC2 bug tracker:
  https://github.com/ldc-developers/ldc/issues/4389

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