[Bug c++/29215] New: Can't find nested type under strange circumstances (outer namespace or unrelated code built without debug info)

[Bug c++/29215] New: Can't find nested type under strange circumstances (outer namespace or unrelated code built without debug info)

[dblaikie at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29215

            Bug ID: 29215
           Summary: Can't find nested type under strange circumstances
                    (outer namespace or unrelated code built without debug
                    info)
           Product: gdb
           Version: 10.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
          Assignee: unassigned at sourceware dot org
          Reporter: dblaikie at gmail dot com
  Target Milestone: ---

a.cpp:
```
void f1();
int main() {
  f1();
}
```
b.cpp:
```
namespace x {
struct t1 {
  t1();
  struct t2 {
    t2();
  };
};
}
x::t1::t1() { }
x::t1::t2::t2() { }
void f1() { }
```
Build the first without debug info, and the second with debug info and
pubnames/gdb-index:
```
$ clang++ -c a.cpp
$ clang++ -c b.cpp -g -ggnu-pubnames -Wl,--gdb-index
$ clang++ a.o b.o -fuse-ld=lld 
$ gdb -ex "ptype x::t1::t2" -ex "ptype x::t1" -ex quit a.out
No type "t1" within class or namespace "x".
type = struct x::t1 {
...
```
But if you add `-g -ggnu-pubnames` to a.cpp, or if you remove the namespace,
the name lookups do seem to work.

(reproduces with GCC-built DWARF too)

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[Bug c++/29215] Can't find nested type under strange circumstances (outer namespace or unrelated code built without debug info)

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29215

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-10-21
     Ever confirmed|0                           |1
                 CC|                            |tromey at sourceware dot org
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
This is a funny one.  The problem is:

(gdb) show lang
The current source language is "auto; currently c".

This happens because 'main' does not have debuginfo
and so the current context is assumed to be C.

Doing "set lang c++" lets this work.

So probably the real question is why "x::t1" works :-)

Confirming this bug, but TBH I don't know if it is fixable
in a reasonable way.  Arguably maybe C and C++ should be
closer together here, though in gdb "C" is also used as
a fallback when the language isn't known, so this may have
adverse consequences.

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[Bug c++/29215] Can't find nested type under strange circumstances (outer namespace or unrelated code built without debug info)

[dblaikie at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29215

--- Comment #2 from David Blaikie <dblaikie at gmail dot com> ---
Ah, thanks - FWIW, this wasn't found in the wild, just something I stumbled
across while reducing/understanding
https://sourceware.org/bugzilla/show_bug.cgi?id=29219 so I wouldn't find this
to be terribly important/high priority.

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