From f9ef654b6393e54ad6284d36a32f1fc56af17b05 Mon Sep 17 00:00:00 2001
From: Shuhei Kadowaki <40514306+aviatesk@users.noreply.github.com>
Date: Wed, 20 Sep 2023 12:58:54 +0900
Subject: [PATCH] inference: handle `Vararg` in `abstract_call_unionall` for
 `argtypes` computed by `abstract_apply` (#51393)

This commit adds special handling for `Vararg` types that may appear at
the end of `argtypes`, as computed by `abstract_apply`. Even though PR

within the abstract state, they can still be part of `argtypes`. As a
result, this kind of special handling is still necessary. It remains an
open question whether we can refactor `abstract_apply` to prevent
`Vararg`s from appearing in `argtypes` in the first place.
---
 base/compiler/abstractinterpretation.jl | 7 ++++++-
 test/compiler/inference.jl              | 7 ++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/base/compiler/abstractinterpretation.jl b/base/compiler/abstractinterpretation.jl
index 973c7dc6f879b..f256f5438bb90 100644
--- a/base/compiler/abstractinterpretation.jl
+++ b/base/compiler/abstractinterpretation.jl
@@ -1874,7 +1874,12 @@ function abstract_call_unionall(interp::AbstractInterpreter, argtypes::Vector{An
         a2 = argtypes[2]
         a3 = argtypes[3]
         ⊑ᵢ = ⊑(typeinf_lattice(interp))
-        nothrow = a2 ⊑ᵢ TypeVar && (a3 ⊑ᵢ Type || a3 ⊑ᵢ TypeVar)
+        if isvarargtype(a3)
+            a3 = unwrapva(a3)
+            nothrow = false
+        else
+            nothrow = a2 ⊑ᵢ TypeVar && (a3 ⊑ᵢ Type || a3 ⊑ᵢ TypeVar)
+        end
         if isa(a3, Const)
             body = a3.val
         elseif isType(a3)
diff --git a/test/compiler/inference.jl b/test/compiler/inference.jl
index 8b980f1fdb17c..25190fe0c16ff 100644
--- a/test/compiler/inference.jl
+++ b/test/compiler/inference.jl
@@ -5,7 +5,7 @@ import Core.Compiler: Const, Conditional, ⊑, ReturnNode, GotoIfNot
 isdispatchelem(@nospecialize x) = !isa(x, Type) || Core.Compiler.isdispatchelem(x)
 
 using Random, Core.IR
-using InteractiveUtils: code_llvm
+using InteractiveUtils
 
 include("irutils.jl")
 
@@ -5101,3 +5101,8 @@ end |> only === Val{5}
 @test fully_eliminated() do
     length(continue_const_prop(1, 5))
 end
+
+# https://github.com/JuliaLang/julia/issues/51310
+@test code_typed() do
+    b{c} = d...
+end |> only |> first isa Core.CodeInfo