Codegen bug: Call parameter type does not match function signature

[wolfgang371]

macro assert(invariant)
    raise("runtime_assert") if !({{invariant}}) # if you omit the () on the conditional, it compliles fine
end

def a(value : String)
    assert(value.is_a?(Int)) # original code had this method in a generic class, with value of type T
    value = [1,value].max # if you put "1" here, you get "BUG: trying to downcast NoReturn (Crystal::NoReturnType) <- String (Crystal::NonGenericClassType) (Exception)"
end

a("42")

# `crystal build fail.cr` yields:
# Invalid memory access (signal 11) at address 0x32356fb
# [0xd3d196] ???
# [0xd3d15a] ???
# [0x35cacc8] ???

I'm using Crystal 1.7.3 on Ubuntu 18.04.

[wolfgang371]

The code is obviously nonsense, it's the result of stripping down a quite big chunk of code.
It seems to be very much related to the parenthesis I needed to introduce in my assert macro since I realized that assert(a != b) is susceptible to the very same missing macro parenthesis problem as in old C.

[straight-shoota]

This is actually a codegen error, unrelated to any macros.
If you expand the macro, you get the same error:

def a(value : String)
    raise("runtime_assert") if !(value.is_a?(Int))
    value = [1,value].max
end

a("42")

Full stack trace with LLVM 15 (Crystal version 1.8.0-dev [3a360b1]):

Module validation failed: Call parameter type does not match function signature!
  %12 = load i8, ptr %11, align 1, !dbg !657
 ptr  %13 = call i32 @"*Array(Int32)@Enumerable(T)#max:Int32"(i8 %12), !dbg !657
 (Exception)
  from src/llvm/module.cr:72:9 in 'verify'
  from src/compiler/crystal/codegen/codegen.cr:378:9 in 'finish'
  from src/compiler/crystal/codegen/codegen.cr:76:7 in 'codegen'
  from src/compiler/crystal/codegen/codegen.cr:72:5 in 'codegen:debug:single_module'
  from src/compiler/crystal/progress_tracker.cr:22:7 in 'codegen'
  from src/compiler/crystal/compiler.cr:162:16 in 'compile'
  from src/compiler/crystal/command/eval.cr:29:5 in 'eval'
  from src/compiler/crystal/command.cr:97:7 in 'run'
  from src/compiler/crystal/command.cr:51:5 in 'run'
  from src/compiler/crystal/command.cr:50:3 in 'run'
  from src/compiler/crystal.cr:11:1 in '__crystal_main'
  from src/crystal/main.cr:115:5 in 'main_user_code'
  from src/crystal/main.cr:101:7 in 'main'
  from src/crystal/main.cr:127:3 in 'main'
  from /lib/x86_64-linux-gnu/libc.so.6 in '??'
  from /lib/x86_64-linux-gnu/libc.so.6 in '__libc_start_main'
  from /home/johannes/src/crystal-lang/crystal/.build/crystal in '_start'
  from ???
Error: you've found a bug in the Crystal compiler. Please open an issue, including source code that will allow us to reproduce the bug: https://github.com/crystal-lang/crystal/issues

The code works fine in the interpreter, btw. ;)

[wolfgang371]

Thanks for your quick reply!
So, maybe you want to change the title...

What about the "BUG: trying to downcast..." - is that related as well?

And what about this macro parenthesis issue - is that really intended?

macro m(x)
    puts(3 * {{x}})
    {% debug %}
end

m(2+1) # expecting 9
# -> puts(3 * 2 + 1)
# -> 7

[straight-shoota]

What about the "BUG: trying to downcast..." - is that related as well?

Probably yes.

And what about this macro parenthesis issue - is that really intended?

Yes. But perhaps this can be improved, see #6254

[wolfgang371]

wrt. macro arguments & parenthesis: as an intermediate step probably some explicit hint in the docs would help a bit.