Mangle conflict after ImportC statement expression gets expanded from macro

[ryuukk]

I'm using ImportC in my project, and i'm compiling it as a shared library, the commit be8668e introduces the following issue:

/usr/bin/ld: warning: size of symbol `_D2it24nk_style_push_style_itemUPS3__C10nk_contextPSQs13nk_style_itemQsZ22__dgliteral_L19113_C28MFZv' changed from 56 in bin/game-lib.o to 58 in bin/game-lib.o
/usr/bin/ld: warning: NOTE: size discrepancies can cause real problems.  Investigation is advised.
/usr/bin/ld: warning: size of symbol `_D2it19nk_style_push_floatUPS3__C10nk_contextPffZ22__dgliteral_L19114_C28MFZv' changed from 56 in bin/game-lib.o to 58 in bin/game-lib.o
/usr/bin/ld: warning: NOTE: size discrepancies can cause real problems.  Investigation is advised.
/usr/bin/ld: warning: size of symbol `_D2it18nk_style_push_vec2UPS3__C10nk_contextPSQs7nk_vec2QlZ22__dgliteral_L19115_C28MFZv' changed from 56 in bin/game-lib.o to 58 in bin/game-lib.o
/usr/bin/ld: warning: NOTE: size discrepancies can cause real problems.  Investigation is advised.
/usr/bin/ld: warning: size of symbol `_D2it19nk_style_push_flagsUPS3__C10nk_contextPkkZ22__dgliteral_L19116_C28MFZv' changed from 56 in bin/game-lib.o to 58 in bin/game-lib.o
/usr/bin/ld: warning: NOTE: size discrepancies can cause real problems.  Investigation is advised.
/usr/bin/ld: warning: size of symbol `_D2it19nk_style_push_colorUPS3__C10nk_contextPSQs8nk_colorQmZ22__dgliteral_L19117_C28MFZv' changed from 56 in bin/game-lib.o to 58 in bin/game-lib.o
/usr/bin/ld: warning: NOTE: size discrepancies can cause real problems.  Investigation is advised.
/usr/bin/ld: warning: size of symbol `_D2it23nk_style_pop_style_itemUPS3__C10nk_contextZ22__dgliteral_L19119_C28MFZv' changed from 56 in bin/game-lib.o to 58 in bin/game-lib.o
/usr/bin/ld: warning: NOTE: size discrepancies can cause real problems.  Investigation is advised.
/usr/bin/ld: warning: size of symbol `_D2it18nk_style_pop_floatUPS3__C10nk_contextZ22__dgliteral_L19120_C28MFZv' changed from 56 in bin/game-lib.o to 58 in bin/game-lib.o
/usr/bin/ld: warning: NOTE: size discrepancies can cause real problems.  Investigation is advised.
/usr/bin/ld: warning: size of symbol `_D2it17nk_style_pop_vec2UPS3__C10nk_contextZ22__dgliteral_L19121_C28MFZv' changed from 56 in bin/game-lib.o to 58 in bin/game-lib.o
/usr/bin/ld: warning: NOTE: size discrepancies can cause real problems.  Investigation is advised.
/usr/bin/ld: warning: size of symbol `_D2it18nk_style_pop_flagsUPS3__C10nk_contextZ22__dgliteral_L19122_C28MFZv' changed from 56 in bin/game-lib.o to 58 in bin/game-lib.o
/usr/bin/ld: warning: NOTE: size discrepancies can cause real problems.  Investigation is advised.
/usr/bin/ld: warning: size of symbol `_D2it18nk_style_pop_colorUPS3__C10nk_contextZ22__dgliteral_L19123_C28MFZv' changed from 56 in bin/game-lib.o to 58 in bin/game-lib.o
/usr/bin/ld: warning: NOTE: size discrepancies can cause real problems.  Investigation is advised.

It's symbols from C source code: https://github.com/Immediate-Mode-UI/Nuklear/

It also causes heavy compilation slowdown

Build flags:

-shared -debug -betterC -fPIC

[ryuukk]

To reproduce::

1. create 2 files:
   • app.d
   • bug.c

app.d

import bug;

bug.c

#define NK_IMPLEMENTATION
#include "nuklear.h"

2. download the file: https://raw.githubusercontent.com/Immediate-Mode-UI/Nuklear/refs/heads/master/nuklear.h

3. compile: dmd -betterC -shared app.d bug.c

ping @dkorpel since you are the author of the PR

and ping @WalterBright since it impacts ImportC

[dkorpel]

I followed your steps, but I don't see those linker warnings or a slowdown. I tried dmd master, be8668e, and the commit before that. They all take ~0.094 seconds and don't output any warnings.

From inspecting nuklear.h and your linker output, I'm guessing there's a name collision when a macro containing an assert() gets expanded multiple times:

#define NK_STYLE_PUSH_IMPLEMENATION(prefix, type, stack) \
...
    NK_ASSERT(ctx);\
...

The GNU assert macro gets expanded to a statement expression, which ImportC translates to a function literal with a supposedly unique "dgliteral_LOCATION" name, but in your case different asserts get the same mangled name.

The location in your linker output point to lines 19113-19123, which doesn't match my copy of nuklear.h. Can you post the exact commit / content of your nuklear.h?

[ryuukk]

To make sure we are testing the same thing

OS: Linux x64
Linker: GNU ld (GNU Binutils) 2.44
LDC used to build DMD: 1.40.0:
Nuklear: master

I'm compiling a debug build of DMD this way: make install HOST_DMD=/usr/bin/ldmd2 ENABLE_RELEASE=0 ENABLE_LTO=0

EDIT:

Can you add -L=-v to the command to build the repro and paste information here please?

[dkorpel]

-L=-v gives:

GNU ld (GNU Binutils) 2.43.1
collect2 version 14.2.1 20250128
/usr/bin/ld -plugin /usr/lib/gcc/x86_64-pc-linux-gnu/14.2.1/liblto_plugin.so -plugin-opt=/usr/lib/gcc/x86_64-pc-linux-gnu/14.2.1/lto-wrapper -plugin-opt=-fresolution=/tmp/ccEUhLIz.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s --build-id --eh-frame-hdr --hash-style=gnu -m elf_x86_64 -shared -o .so /usr/lib/gcc/x86_64-pc-linux-gnu/14.2.1/../../../../lib/crti.o /usr/lib/gcc/x86_64-pc-linux-gnu/14.2.1/crtbeginS.o -L/home/dennis/repos/dmd/generated/linux/debug/64/../../../../../phobos/generated/linux/debug/64 -L/usr/lib/gcc/x86_64-pc-linux-gnu/14.2.1 -L/usr/lib/gcc/x86_64-pc-linux-gnu/14.2.1/../../../../lib -L/lib/../lib -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-pc-linux-gnu/14.2.1/../../.. app.o -v --export-dynamic -lpthread -lm -lrt -ldl -lgcc --push-state --as-needed -lgcc_s --pop-state -lc -lgcc --push-state --as-needed -lgcc_s --pop-state /usr/lib/gcc/x86_64-pc-linux-gnu/14.2.1/crtendS.o /usr/lib/gcc/x86_64-pc-linux-gnu/14.2.1/../../../../lib/crtn.o

Edit: I can reproduce it now. I'll try to reduce it.

[dkorpel]

Self-contained example:

#include "assert.h"

int* p;

#define IMPL() \
f()\
{\
    assert(p);\
    assert(4 < 3);\
}

void IMPL()

void main(void) {}

[ryuukk]

Thanks for the fix