From d81dcd54ee2a8b3689e8e47907333f0293d819c0 Mon Sep 17 00:00:00 2001
From: lkdvos <ldevos98@gmail.com>
Date: Wed, 12 Aug 2026 16:07:01 +0200
Subject: [PATCH] fix `@planar` backend and allocator insertion

`_insert_planar_operations` rewrites the tensor calls to
`GlobalRef(TensorKit, :planar*!)`, which `TO.insertargument` does not
match, so `@planar backend=... ` and `@planar allocator=...` silently
dropped both arguments from the planar calls.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
---
 src/planar/macros.jl         |  6 ++++--
 src/planar/postprocessors.jl | 16 ++++++++++++++--
 test/tensors/planar.jl       | 27 +++++++++++++++++++++++++++
 3 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/src/planar/macros.jl b/src/planar/macros.jl
index c2afcb596..16f7f1c0a 100644
--- a/src/planar/macros.jl
+++ b/src/planar/macros.jl
@@ -30,7 +30,7 @@ function planarparser(planarexpr, kwargs...)
         if name == :backend
             hasbackend = true
             backend = val
-            push!(parser.postprocessors, ex -> TO.insertbackend(ex, backend))
+            push!(parser.postprocessors, ex -> insertplanarbackend(ex, backend))
             break
         end
     end
@@ -39,8 +39,10 @@ function planarparser(planarexpr, kwargs...)
             allocator = val
             if !hasbackend
                 backend = Expr(:call, GlobalRef(TensorOperations, :DefaultBackend))
-                push!(parser.postprocessors, ex -> TO.insertbackend(ex, backend))
+                push!(parser.postprocessors, ex -> insertplanarbackend(ex, backend))
             end
+            push!(parser.postprocessors, ex -> insertplanarallocator(ex, allocator))
+            # the alloc/free calls are still `GlobalRef(TensorOperations, ...)`
             push!(parser.postprocessors, ex -> TO.insertallocator(ex, allocator))
             break
         end
diff --git a/src/planar/postprocessors.jl b/src/planar/postprocessors.jl
index 7ae527383..8cf55ea2f 100644
--- a/src/planar/postprocessors.jl
+++ b/src/planar/postprocessors.jl
@@ -90,6 +90,18 @@ function _insert_planar_operations(ex)
     return ex
 end
 
+# like `TO.insertargument`, but matching `GlobalRef`s into `TensorKit`
+function _insertargument(ex, arg, methods)
+    if isexpr(ex, :call) && ex.args[1] isa GlobalRef &&
+            ex.args[1].mod === TensorKit && ex.args[1].name ∈ methods
+        return Expr(:call, ex.args..., arg)
+    elseif isa(ex, Expr)
+        return Expr(ex.head, (_insertargument(e, arg, methods) for e in ex.args)...)
+    else
+        return ex
+    end
+end
+
 """
     insertplanarbackend(ex, backend)
 
@@ -98,7 +110,7 @@ Insert the backend argument into the tensor operation methods `planaradd!`, `pla
 See also: [`TensorOperations.insertbackend`](@ref).
 """
 function insertplanarbackend(ex, backend)
-    return TO.insertargument(ex, backend, (:planaradd!, :planartrace!, :planarcontract!))
+    return _insertargument(ex, backend, _PLANAR_OPERATIONS)
 end
 
 """
@@ -109,5 +121,5 @@ Insert the allocator argument into the tensor operation methods `planaradd!`, `p
 See also: [`TensorOperations.insertallocator`](@ref).
 """
 function insertplanarallocator(ex, allocator)
-    return TO.insertargument(ex, allocator, (:planaradd!, :planartrace!, :planarcontract!))
+    return _insertargument(ex, allocator, _PLANAR_OPERATIONS)
 end
diff --git a/test/tensors/planar.jl b/test/tensors/planar.jl
index 8e8a3e778..99ae49ebd 100644
--- a/test/tensors/planar.jl
+++ b/test/tensors/planar.jl
@@ -101,6 +101,33 @@ end
 @testset "@planar" verbose = true begin
     T = ComplexF64
 
+    @testset "backend and allocator insertion" begin
+        # trailing arguments of every `planar*!` call in `ex`
+        function planartrailing(ex, out = Any[])
+            ex isa Expr || return out
+            if Meta.isexpr(ex, :call) && ex.args[1] isa GlobalRef &&
+                    ex.args[1].name in (:planaradd!, :planartrace!, :planarcontract!)
+                push!(out, ex.args[end])
+            end
+            foreach(a -> planartrailing(a, out), ex.args)
+            return out
+        end
+
+        ex = @macroexpand @planar backend = MarkerBackend() C[i; j] := A[i; k l] *
+            τ[k l; m n] * B[m n; j]
+        trailing = planartrailing(ex)
+        @test !isempty(trailing)
+        @test all(==(:(MarkerBackend())), trailing)
+
+        # an allocator implies a default backend, and both land on the planar calls
+        ex = @macroexpand @planar allocator = MarkerAllocator() C[i; j] := A[i; k l] *
+            τ[k l; m n] * B[m n; j]
+        trailing = planartrailing(ex)
+        @test !isempty(trailing)
+        @test all(==(:(MarkerAllocator())), trailing)
+        @test occursin("DefaultBackend", string(ex))
+    end
+
     @testset "contractcheck" begin
         V = ℂ^2
         A = rand(T, V ⊗ V ← V)