From 1a1427325fa933331ab979c1891c55cc053479f5 Mon Sep 17 00:00:00 2001
From: Tim Besard <tim.besard@gmail.com>
Date: Thu, 22 Jan 2026 16:43:02 +0100
Subject: [PATCH] Fix  missing  and  fields

---
 Compiler/src/typeinfer.jl |  2 ++
 Compiler/test/ssair.jl    | 13 +++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/Compiler/src/typeinfer.jl b/Compiler/src/typeinfer.jl
index e3b7ee1f4926c..c97cf8b7f62a5 100644
--- a/Compiler/src/typeinfer.jl
+++ b/Compiler/src/typeinfer.jl
@@ -1186,6 +1186,8 @@ function codeinfo_for_const(::AbstractInterpreter, mi::MethodInstance, worlds::W
     tree.min_world = first(worlds)
     tree.max_world = last(worlds)
     tree.edges = edges
+    tree.nargs = UInt(nargs)
+    tree.isva = method.isva
     set_inlineable!(tree, true)
     tree.parent = mi
     return tree
diff --git a/Compiler/test/ssair.jl b/Compiler/test/ssair.jl
index 7aca2b8977a4e..f8d8a14adf9d7 100644
--- a/Compiler/test/ssair.jl
+++ b/Compiler/test/ssair.jl
@@ -845,3 +845,16 @@ end
 let ir = Base.code_ircode(_worker_task57153, (), optimize_until="CC: COMPACT_2")[1].first
     @test findfirst(x->x==0, ir.cfg.blocks[1].preds) !== nothing
 end
+
+# issue #59413 - codeinfo_for_const should set nargs and isva
+let
+    _const_return_func(@nospecialize(x)) = 42
+    mi = Compiler.specialize_method(only(methods(_const_return_func)), Tuple{typeof(_const_return_func), Int}, Core.svec())
+    worlds = Compiler.WorldRange(Base.get_world_counter(), Base.get_world_counter())
+    ci = Compiler.codeinfo_for_const(Compiler.NativeInterpreter(), mi, worlds, Core.svec(), 42)
+    @test ci.nargs == 2
+    @test ci.isva == false
+    # inflate_ir! should succeed now that nargs/isva are set
+    ir = Compiler.inflate_ir!(ci, mi)
+    @test ir isa Compiler.IRCode
+end