Recursion in unused.zig causes infinite loop

[F3real]

Test example bad\unused_decl.zig causes stack overflow due to recursion having infinite loop.

It goes to:

checkNamespace( container_decl_two ...)
→ checkNamespaceItem (fn_decl...)
→ checkNamespaceItem (fn_proto...)
→ searchForNameInNamespace
→ checkValueForName(simple_var_decl...)

where for init node we have container_decl_two which calls checkNamespace and it repeats.

Can be fixed by just removing:

         .container_decl, .container_decl_trailing => {
             const x = ast.containerDecl(node);
             if (try checkValuesForName(ast, search_name, x.ast.members, writer, file_name, node)) return true;
-            try checkNamespace(ast, node, writer, file_name);
             return false;
         },

But probably larger refactor would be needed to make it more performant/safer.

[nektro]

can u post the zig file that tripped this issue as well? I'm happy to look into this

[F3real]

 C:\Users\user\ziglint>zig build -Dmode=Debug -j1
 C:\Users\user\ziglint> .\zig-out\bin\ziglint.exe
./bad\dupe_import.zig:5:11: found duplicate import of "std"
./bad\file_as_struct.zig:1:1: found top level fields, file name should be capitalized
./bad\todo.zig:6:1: TODO: maybe the return type should be !void
./bad\todo.zig:8:5: TODO: switch to something that also prints in release mode
./bad\unused_decl.zig:12:11: unused local declaration 'bar'
Stack Overflow

It can be reproduced just by running ziglint on ./bad\unused_decl.zig example.

[nektro]

~~oh hmmm. seems that's only propagating on windows. on linux with~~

[meghan@nixos:/run/media/meghan/dev/ziglint]$ zig build run
./bad/file_as_struct.zig:1:1: found top level fields, file name should be capitalized
./bad/unused_function.zig:9:4: unused local function 'foo'
./bad/todo.zig:6:1: TODO: maybe the return type should be !void
./bad/todo.zig:8:5: TODO: switch to something that also prints in release mode
./bad/unused_decl.zig:12:11: unused local declaration 'bar'
./bad/unused_decl.zig:16:8: unused local function 'baz'
./bad/unused_decl.zig:3:7: unused local declaration 'root'
./bad/dupe_import.zig:5:11: found duplicate import of "std"
./src/main.zig:93:5: TODO: eventually do .gitignore parsing

[meghan@nixos:/run/media/meghan/dev/ziglint]$ ./zig-out/bin/ziglint 
./bad/file_as_struct.zig:1:1: found top level fields, file name should be capitalized
./bad/unused_function.zig:9:4: unused local function 'foo'
./bad/todo.zig:6:1: TODO: maybe the return type should be !void
./bad/todo.zig:8:5: TODO: switch to something that also prints in release mode
./bad/unused_decl.zig:12:11: unused local declaration 'bar'
Segmentation fault (core dumped)

this behavior is much weirder than i expected. digging...

[nektro]

[meghan@nixos:/run/media/meghan/dev/ziglint]$ gdb ./zig-out/bin/ziglint 
GNU gdb (GDB) 13.1
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For help, type "help".
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Reading symbols from ./zig-out/bin/ziglint...
(gdb) r
Starting program: /run/media/meghan/dev/ziglint/zig-out/bin/ziglint 
./bad/file_as_struct.zig:1:1: found top level fields, file name should be capitalized
./bad/unused_function.zig:9:4: unused local function 'foo'
./bad/todo.zig:6:1: TODO: maybe the return type should be !void
./bad/todo.zig:8:5: TODO: switch to something that also prints in release mode
./bad/unused_decl.zig:12:11: unused local declaration 'bar'

Program received signal SIGSEGV, Segmentation fault.
0x000000000032467c in __zig_probe_stack () at /home/meghan/.local/share/zig/lib/compiler_rt/stack_probe.zig:53
53                  asm volatile (
(gdb) bt
#0  0x000000000032467c in __zig_probe_stack () at /home/meghan/.local/share/zig/lib/compiler_rt/stack_probe.zig:53
Backtrace stopped: Cannot access memory at address 0x7ffffeffe970
(gdb) 

[nektro]

bottom of strace stack is

write(1, "bar", 3)                      = 3
write(1, "'\n", 2)                      = 2
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x7ffc42883d90} ---
--- SIGSEGV {si_signo=SIGSEGV, si_code=SI_KERNEL, si_addr=NULL} ---
+++ killed by SIGSEGV (core dumped) +++
Segmentation fault (core dumped)