From 78023a81fb3843cb2e3b3434ad9b7b1c0fe362e8 Mon Sep 17 00:00:00 2001
From: ChrisRackauckas-Claude <accounts@chrisrackauckas.com>
Date: Wed, 26 Aug 2026 04:55:08 -0400
Subject: [PATCH] Fix CanonicalMoments SymbolicsExt precompilation under
 Symbolics 7

The docs build fails while precompiling `CanonicalMoments -> SymbolicsExt`,
which cascades into an OUQBase precompile failure, because the extension
relies on two things that no longer hold with Symbolics 7:

- `@register_array_symbolic` inspects each declared argument type, and
  `AbstractVecOrMat{<:Real}` is a `UnionAll` wrapping a `Union`. Symbolics 7
  reaches for `.parameters` on it, raising
  `FieldError: type Union has no field parameters`. Declaring the argument as
  `AbstractArray{<:Real}` keeps both the vector and matrix cases without
  introducing a `Union`.

- `Symbolics.array_term` was removed in Symbolics 7, so the manual companion
  matrix term construction cannot work. Registering
  `CanonicalMoments._companion_matrix` instead lets the macro build the lazy
  array term for symbolic inputs and fall through to the existing numeric
  implementation otherwise.

Verified that the extension precompiles and that the symbolic support/weight
path round-trips against the numeric implementation on both Symbolics 6.29.2
and 7.36.0, and that `docs/make.jl` completes.

Co-authored-by: Cursor <cursoragent@cursor.com>
---
 lib/CanonicalMoments/ext/SymbolicsExt.jl | 26 ++++++++++--------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/lib/CanonicalMoments/ext/SymbolicsExt.jl b/lib/CanonicalMoments/ext/SymbolicsExt.jl
index 8949d76..451b742 100644
--- a/lib/CanonicalMoments/ext/SymbolicsExt.jl
+++ b/lib/CanonicalMoments/ext/SymbolicsExt.jl
@@ -1,8 +1,6 @@
 module SymbolicsExt
 using Symbolics
-import Symbolics: unwrap, wrap, array_term
 using CanonicalMoments
-using LinearAlgebra
 
 @register_array_symbolic (alg::CanonicalMoments.EigvalSupportAlg)(M::AbstractMatrix{<:Real}) begin
     size = (size(M)[1],)
@@ -14,26 +12,24 @@ end
     eltype = eltype(M)
 end
 
+# `AbstractVecOrMat` is a `Union` alias, which `@register_array_symbolic` cannot
+# introspect; `AbstractArray` covers both the vector and matrix cases.
 @register_array_symbolic (alg::CanonicalMoments.EigvecWeightAlg)(
     M::AbstractMatrix{<:Real},
-    λ::AbstractVecOrMat{<:Real},
+    λ::AbstractArray{<:Real},
 ) begin
     size = size(M)
     eltype = eltype(M)
 end
 
-function CanonicalMoments._companion_matrix(B::Vector{Num}, C::Vector{Num})
-    dv = -B
-    ndims = length(B)
-    ev = sqrt.(C[2:end]) # Probably use views here
-    _comp_mat_unwrapped = array_term(
-        SymTridiagonal,
-        unwrap.(dv),
-        unwrap.(ev);
-        eltype = Real,
-        size = (ndims, ndims),
-    )
-    return wrap(_comp_mat_unwrapped)
+# Registering the companion matrix constructor keeps it lazy for symbolic inputs
+# while deferring to the numeric implementation otherwise.
+@register_array_symbolic CanonicalMoments._companion_matrix(
+    B::AbstractVector{<:Real},
+    C::AbstractVector{<:Real},
+) begin
+    size = (length(B), length(B))
+    eltype = Real
 end
 
 end