Nim Version
Nim Compiler Version 2.3.1 [Linux: arm64]
Compiled at 2026-06-02
Copyright (c) 2006-2026 by Andreas Rumpf
git hash: 73986c0
active boot switches: -d:release
Description
Compiling following code with nim cpp --cc:clang generates compile error from clang:
proc testVarRet(x: var int): var int = x
proc testProcTypeParam(prc: proc (x: var int): var int {.nimcall.}) = discard
testProcTypeParam(testVarRet)It compiles without error when compiled with nim c or compiled without clang backend.
Current Output
testvarret/debug/@mtestvarret.nim.cpp:119:56: error: no matching function for call to 'testProcTypeParam__testvarret_u23'
119 | nimlf_(5, "testvarret.nim");testProcTypeParam__testvarret_u23(testVarRet__testvarret_u1);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
testvarret/debug/@mtestvarret.nim.cpp:73:31: note: candidate function not viable: no known conversion from 'NI *(NI &)' (aka 'long *(long &)') to 'tyProc__6ZQ0ZDxLqdLoyCLmNo1XEw' (aka 'long &(*)(long &)') for 1st argument
73 | N_LIB_PRIVATE N_NIMCALL(void, testProcTypeParam__testvarret_u23)(tyProc__6ZQ0ZDxLqdLoyCLmNo1XEw prc_p0) {
| ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Nim/lib/nimbase.h:254:44: note: expanded from macro 'N_NIMCALL'
254 | # define N_NIMCALL(rettype, name) rettype name /* no modifier */
|
1 error generated.
Expected Output
Known Workarounds
No response
Additional Information
When Nim compiled above code with nim cpp, it generates code like this:
typedef int& (tyProc)(int& x_p0);
int* testVarRet(int& x) {
return &x;
}
void testProcTypeParam(tyProc prc) {
}
int main()
{
testProcTypeParam(testVarRet);
}The type of testVarRet is int* (*)(int&) and it is converted to type int& (*)(int&) when it is passed to testProcTypeParam.
gcc compiles this code without error with -fpermissive flag.
But clang generates compile error even if it is compiled with -fpermissive flag.
Nim Version
Nim Compiler Version 2.3.1 [Linux: arm64]
Compiled at 2026-06-02
Copyright (c) 2006-2026 by Andreas Rumpf
git hash: 73986c0
active boot switches: -d:release
Description
Compiling following code with
nim cpp --cc:clanggenerates compile error from clang:It compiles without error when compiled with
nim cor compiled without clang backend.Current Output
Expected Output
Known Workarounds
No response
Additional Information
When Nim compiled above code with
nim cpp, it generates code like this:The type of
testVarRetisint* (*)(int&)and it is converted to typeint& (*)(int&)when it is passed totestProcTypeParam.gcc compiles this code without error with
-fpermissiveflag.But clang generates compile error even if it is compiled with
-fpermissiveflag.