Casting a procedure to a type that differs only by parameter names causes incorrect complation and llvm backend assert #5497
Description
Context
Odin: dev-2025-07:315cd51f7
OS: Windows 11 Home Basic (version: 24H2), build 26100.4652
CPU: AMD Ryzen 5 5600X 6-Core Processor
RAM: 32712 MiB
Backend: LLVM 20.1.0
Expected Behavior
Casting to a procedure type that differs only by parameter names and then calling the procedure using the new names should work
ProcA :: proc(a: int) {}
ProcA(a = 0)
ProcB :: cast(proc(b: int)) ProcA
ProcB(b = 0)
ProcC := proc(a: int) {}
ProcC(a = 0)
ProcD := cast(proc(b: int)) ProcC
ProcD(b = 0)Current Behavior
Casting works in all cases but calling causes either seemingly wrong compiler errors or an llvm assertion
// Odin: dev-2025-07:315cd51f7
// OS: Windows 11 Home Basic (version: 24H2), build 26100.4652
// CPU: AMD Ryzen 5 5600X 6-Core Processor
// RAM: 32712 MiB
// Backend: LLVM 20.1.0
package main
main :: proc()
{
ProcA :: proc(a: int){}
ProcA(a = 0)
when false
{
// D:\odin\src\llvm_backend_proc.cpp(4295): Assertion Failure: `param_index >= 0`
(cast(proc(b: int)) ProcA)(b = 0)
}
when false
{
// W:/proc_lit_llvm_assert.odin(32:3) Error: Parameter 'a' of type 'int' is missing in procedure call
// ProcB(b = 0)
// ^~~~~~~~~~~^
// W:/proc_lit_llvm_assert.odin(32:9) Error: No parameter named 'b' for this procedure type
// ProcB(b = 0)
// ^~~~^
ProcB : proc(b: int) : ProcA
ProcB(b = 0)
}
when false
{
// W:/proc_lit_llvm_assert.odin(45:3) Error: Parameter 'a' of type 'int' is missing in procedure call
// ProcB(b = 0)
// ^~~~~~~~~~~^
// W:/proc_lit_llvm_assert.odin(45:9) Error: No parameter named 'b' for this procedure type
// ProcB(b = 0)
// ^~~~^
ProcB :: cast(proc(b: int)) ProcA
ProcB(b = 0)
}
ProcC := proc(a: int) {}
when false
{
// D:\odin\src\llvm_backend_proc.cpp(4295): Assertion Failure: `param_index >= 0`
(cast(proc(b: int)) ProcC)(b = 0)
}
ProcD : proc(b: int) = ProcC
ProcD(b = 0)
}Failure Information (for bugs)
Please help provide information about the failure if this is a bug. If it is not a bug, please remove the rest of this template.
Steps to Reproduce
compile the snippet provided in "Current Behavior" and toggle one of the when false statements.