From 818ec7be2f087fa89926da400b17faf7671db24f Mon Sep 17 00:00:00 2001
From: Tangi Migot <tangi.migot@gmail.com>
Date: Sat, 17 Aug 2024 18:44:34 +0200
Subject: [PATCH] Add eltype for NLPModels (#481)

---
 src/nlp/utils.jl | 7 +++++++
 test/nlp/api.jl  | 1 +
 test/nls/api.jl  | 1 +
 3 files changed, 9 insertions(+)

diff --git a/src/nlp/utils.jl b/src/nlp/utils.jl
index dd16b42b..8f2b4a1b 100644
--- a/src/nlp/utils.jl
+++ b/src/nlp/utils.jl
@@ -141,3 +141,10 @@ macro default_counters(Model, inner)
   )
   ex
 end
+
+"""
+    eltype(nlp::AbstractNLPModel{T, S})
+
+Element type of `nlp.meta.x0`.
+"""
+Base.eltype(nlp::AbstractNLPModel{T, S}) where {T, S} = eltype(nlp.meta.x0)
diff --git a/test/nlp/api.jl b/test/nlp/api.jl
index 6d7d209e..730dc5ca 100644
--- a/test/nlp/api.jl
+++ b/test/nlp/api.jl
@@ -7,6 +7,7 @@
   H(x, y) = H(x) + y[2] * [-0.5 0; 0 -2.0]
 
   nlp = SimpleNLPModel()
+  @test eltype(nlp) == Float64
   n = nlp.meta.nvar
   m = nlp.meta.ncon
 
diff --git a/test/nls/api.jl b/test/nls/api.jl
index 530696a7..c033dc6d 100644
--- a/test/nls/api.jl
+++ b/test/nls/api.jl
@@ -4,6 +4,7 @@
   HF(x, w) = w[2] * [-20.0 0; 0 0]
 
   nls = SimpleNLSModel()
+  @test eltype(nls) == Float64
   n = nls.meta.nvar
   m = nls.meta.ncon
   ne = nls_meta(nls).nequ