cl:compile with clang++

[luoliwoshang]

fixed #1146

with the case for #1146,can run normally

git clone https://github.com/goplus/lib --branch v0.2.0
cd ./lib/cpp/std/_demo/cpphello
llgo run .

git:(main) llgo run .
Hello world
Hello world
12

---

todo: update https://github.com/goplus/lib/blob/v0.2.0/py/_pyg/module.c to use extern "C" to ensure symbol name

ld64.lld: error: undefined symbol: llgoLoadPyModSyms
>>> referenced by /var/folders/y6/nj790rtn62lfktb1sh__79hc0000gn/T/ba2c279d93bbfecee748b353857265db8181469610e61cab9f43750ad4f70fa9-d-871d82.o:(symbol github.com/goplus/llgo/_xtool/pydump.init+0x5c)
>>> did you mean to declare llgoLoadPyModSyms(PyObject*, ...) as extern "C"?
>>> defined in: /var/folders/y6/nj790rtn62lfktb1sh__79hc0000gn/T/02808894111fc2794d2934f95173b15acc56cff66337b2cddb449c0b58c9a6ba-dmodule-c91f13.o

---

use the clang++ to compiler,when compile with use a wrap .c's file like runtime/internal/clite/bitcast/bitcast.go ,will got follow

ld64.lld: error: undefined symbol: llgoToFloat64
>>> referenced by /var/folders/5j/sgtxqmbn1hbdqtgx5kkp6y700000gn/T/a06741472c6f22e6e842173a0de2302c1100e20e1ae0d3b2016a2e50d15ad40a-d-333cbb.o:(symbol github.com/goplus/llgo/runtime/internal/runtime.printanycustomtype+0x508)
>>> did you mean to declare llgoToFloat64(long long) as extern "C"?
>>> defined in: /var/folders/5j/sgtxqmbn1hbdqtgx5kkp6y700000gn/T/462e5a14b76a549cc31bd8e6feea9ffe78e028b1106bfb2bb15a8e80714fc2ee-dcast-18caea.o

ld64.lld: error: undefined symbol: llgoToFloat32
>>> referenced by /var/folders/5j/sgtxqmbn1hbdqtgx5kkp6y700000gn/T/a06741472c6f22e6e842173a0de2302c1100e20e1ae0d3b2016a2e50d15ad40a-d-333cbb.o:(symbol github.com/goplus/llgo/runtime/internal/runtime.printanycustomtype+0x404)
>>> did you mean to declare llgoToFloat32(int) as extern "C"?
>>> defined in: /var/folders/5j/sgtxqmbn1hbdqtgx5kkp6y700000gn/T/462e5a14b76a549cc31bd8e6feea9ffe78e028b1106bfb2bb15a8e80714fc2ee-dcast-18caea.o
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
panic: exit status 1

this question is when use clang++ to compile .c file,the symbol name is mangled.

/opt/homebrew/Cellar/llvm@19/19.1.7/bin/clang++ -emit-llvm -S -o /Users/zhangzhiyang/Library/Caches/go-build/46/462e5a14b76a549cc31bd8e6feea9ffe78e028b1106bfb2bb15a8e80714fc2ee-dcast.c.ll -c /Users/zhangzhiyang/Documents/Code/goplus/llgo/runtime/internal/clite/bitcast/_cast/cast.c

the correspoding .ll like this , the function name is mangled

; Function Attrs: mustprogress noinline nounwind optnone ssp uwtable(sync)
define noundef double @_Z13llgoToFloat64x(i64 noundef %0) #0 {
  %2 = alloca i64, align 8
  %3 = alloca %union.castUnion, align 8
  store i64 %0, ptr %2, align 8
  %4 = load i64, ptr %2, align 8
  store i64 %4, ptr %3, align 8
  %5 = load double, ptr %3, align 8
  ret double %5
}

so we need make these c file to cpp file ,and with a extern "C" to make symbol correct with .c to .cpp
cast.c -> cast.cpp

+ extern "C" { 

double llgoToFloat64(long long v)
{
    castUnion k;
    k.f = v;
    return k.v;
}

+ }

• other solution is when the source file is with .c,we make the clang++ use -x c mode to compile it to ir,we can get a no mangled symbol.

/opt/homebrew/Cellar/llvm@19/19.1.7/bin/clang++ -x c -emit-llvm -S -o ./test.ll -c /Users/zhangzhiyang/Documents/Code/goplus/llgo/runtime/internal/clite/bitcast/_cast/cast.c

; ModuleID = '/Users/zhangzhiyang/Documents/Code/goplus/llgo/runtime/internal/clite/bitcast/_cast/cast.c'
source_filename = "/Users/zhangzhiyang/Documents/Code/goplus/llgo/runtime/internal/clite/bitcast/_cast/cast.c"
target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128-Fn32"
target triple = "arm64-apple-macosx15.0.0"

%union.castUnion = type { double }

; Function Attrs: noinline nounwind optnone ssp uwtable(sync)
define double @llgoToFloat64(i64 noundef %0) #0 {
  %2 = alloca i64, align 8
  %3 = alloca %union.castUnion, align 8
  store i64 %0, ptr %2, align 8
  %4 = load i64, ptr %2, align 8
  store i64 %4, ptr %3, align 8
  %5 = load double, ptr %3, align 8
  ret double %5
}

; Function Attrs: noinline nounwind optnone ssp uwtable(sync)
define float @llgoToFloat32(i32 noundef %0) #0 {
  %2 = alloca i32, align 4
  %3 = alloca %union.castUnion, align 8
  store i32 %0, ptr %2, align 4
  %4 = load i32, ptr %2, align 4
  %5 = sext i32 %4 to i64
  store i64 %5, ptr %3, align 8
  %6 = load float, ptr %3, align 8
  ret float %6
}

[luoliwoshang]

libunwind.h will not found ,so when compile linux,to add $(llvm-config --cflags) for compile.

clang++ -emit-llvm -S -o /home/runner/.cache/go-build/02/0293ed8bec74bf22083a36df5d607e76abe301dd598dc3f1ed1c5630e5b817b8-ddebug.cpp.ll -c /home/runner/work/llgo/llgo/runtime/internal/clite/debug/_wrap/debug.cpp
/home/runner/work/llgo/llgo/runtime/internal/clite/debug/_wrap/debug.cpp:10:10: fatal error: 'libunwind.h' file not found

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.64%. Comparing base (47c119a) to head (93197e7).
Report is 18 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1147   +/-   ##
=======================================
  Coverage   86.64%   86.64%           
=======================================
  Files          29       29           
  Lines        7343     7343           
=======================================
  Hits         6362     6362           
  Misses        914      914           
  Partials       67       67           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.