[llvm-bugs] [Bug 52582] New: LLDB confuses multiple global variables with the same name (even when they are in different namespace)

via llvm-bugs llvm-bugs at lists.llvm.org
Mon Nov 22 09:12:07 PST 2021


            Bug ID: 52582
           Summary: LLDB confuses multiple global variables with the same
                    name (even when they are in different namespace)
           Product: lldb
           Version: unspecified
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: All Bugs
          Assignee: lldb-dev at lists.llvm.org
          Reporter: vyng at google.com
                CC: jdevlieghere at apple.com, llvm-bugs at lists.llvm.org

Our binary has multiple global variables with the same basename but in
different namespaces. (Eg., lld::macho::symtab vs lld::elf::symtab,
lld::macho::in vs lld::elf::in, ...)

Run the LLD linker under LLDB: (best to use MachO port to demonstrate this

lldb -- ld64.lld.darwninnew <... rest of args>

Set a breakpoint anywhere - but for best effect, here:

(ie., right after `symtab` is set)

Try and print `symtab` or `in.got`:

(lldb) b Driver.cpp:1139
Breakpoint 1: 3 locations.
(lldb) run
Process 13244 launched:
'/Users/vyng/repo/llvm-project/build_lld/bin/ld64.lld.darwinnew' (x86_64)
Process 13244 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.2
    frame #0: 0x0000000100a0856f
ld64.lld.darwinnew`lld::macho::link(argsArr=ArrayRef<const char *> @
0x00007ff7bfefeeb0, canExitEarly=true, stdoutOS=0x00000001093b83a8,
stderrOS=0x00000001093b8410) at Driver.cpp:1139:12
   1137   config = make<Configuration>();
   1138   symtab = make<SymbolTable>();
-> 1139   target = createTargetInfo(args);
   1140   depTracker =
   1142   if (errorCount())
Target 0: (ld64.lld.darwinnew) stopped.
(lldb) print symtab
(lld::elf::SymbolTable *) $0 = nullptr
(lldb) print in.got
(lld::elf::GotSection *) $1 = nullptr
(lldb) print lld::macho::in.got

Since the code that the breakpoint stopped on referred to the variable as
simply `symtab`, I would have expected LLDB's print to allow me to also use

What actually happened:
LLDB always picked the globals from lld::elf .
(presumably because it's alphabetically before ::macho)

(Tested this with GDB and it didn't have this issue)

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