From eec9d3e1fcaf5e7872d83b0d40904985044fee53 Mon Sep 17 00:00:00 2001
From: odow <o.dowson@gmail.com>
Date: Fri, 29 Oct 2021 13:28:24 +1300
Subject: [PATCH 1/3] [Utilities] Fix getter in UniversalFallback

---
 src/Utilities/universalfallback.jl  | 6 ++++--
 test/Utilities/universalfallback.jl | 7 +++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/Utilities/universalfallback.jl b/src/Utilities/universalfallback.jl
index 29c56dd5d6..9a96a918a9 100644
--- a/src/Utilities/universalfallback.jl
+++ b/src/Utilities/universalfallback.jl
@@ -258,10 +258,12 @@ end
 
 # Attributes
 function _get(uf::UniversalFallback, attr::MOI.AbstractOptimizerAttribute)
-    return uf.optattr[attr]
+    return get(uf.optattr, attr, nothing)
 end
 
-_get(uf::UniversalFallback, attr::MOI.AbstractModelAttribute) = uf.modattr[attr]
+function _get(uf::UniversalFallback, attr::MOI.AbstractModelAttribute)
+    return get(uf.modattr, attr, nothing)
+end
 
 function _get(
     uf::UniversalFallback,
diff --git a/test/Utilities/universalfallback.jl b/test/Utilities/universalfallback.jl
index 5df504866f..d3908caed4 100644
--- a/test/Utilities/universalfallback.jl
+++ b/test/Utilities/universalfallback.jl
@@ -373,6 +373,13 @@ function test_show()
     return
 end
 
+function test_missing_attribute()
+    model = MOI.Utilities.UniversalFallback(MOI.Utilities.Model{Float64}())
+    @test MOI.get(model, MOI.Test.UnknownModelAttribute()) === nothing
+    @test MOI.get(model, MOI.TimeLimitSec()) === nothing
+    return
+end
+
 end  # module
 
 TestUniversalFallback.runtests()

From 416e887a3a84ffbb0dda44197067917af2e1ae5d Mon Sep 17 00:00:00 2001
From: odow <o.dowson@gmail.com>
Date: Fri, 29 Oct 2021 13:42:45 +1300
Subject: [PATCH 2/3] Other fixes

---
 src/FileFormats/MOF/nonlinear.jl | 9 +++------
 src/FileFormats/NL/NL.jl         | 8 ++++----
 src/Utilities/print.jl           | 3 +++
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/FileFormats/MOF/nonlinear.jl b/src/FileFormats/MOF/nonlinear.jl
index 6c84f2da2d..6f695fa555 100644
--- a/src/FileFormats/MOF/nonlinear.jl
+++ b/src/FileFormats/MOF/nonlinear.jl
@@ -62,12 +62,9 @@ function write_nlpblock(
     model::Model,
     name_map::Dict{MOI.VariableIndex,String},
 ) where {T<:Object}
-    # TODO(odow): is there a better way of checking if the NLPBlock is set?
-    nlp_block = try
-        MOI.get(model, MOI.NLPBlock())
-    catch ex
-        @assert isa(ex, KeyError)
-        return  # No NLPBlock set.
+    nlp_block = MOI.get(model, MOI.NLPBlock())
+    if nlp_block === nothing
+        return
     end
     MOI.initialize(nlp_block.evaluator, [:ExprGraph])
     variables = MOI.get(model, MOI.ListOfVariableIndices())
diff --git a/src/FileFormats/NL/NL.jl b/src/FileFormats/NL/NL.jl
index fa8b9ed517..ff7a12cdcc 100644
--- a/src/FileFormats/NL/NL.jl
+++ b/src/FileFormats/NL/NL.jl
@@ -243,10 +243,10 @@ MOI.initialize(::_LinearNLPEvaluator, ::Vector{Symbol}) = nothing
 function MOI.copy_to(dest::Model, model::MOI.ModelLike)
     mapping = MOI.Utilities.IndexMap()
     # Initialize the NLP block.
-    nlp_block = try
-        MOI.get(model, MOI.NLPBlock())
-    catch
-        MOI.NLPBlockData(MOI.NLPBoundsPair[], _LinearNLPEvaluator(), false)
+    nlp_block = MOI.get(model, MOI.NLPBlock())
+    if nlp_block === nothing
+        nlp_block =
+            MOI.NLPBlockData(MOI.NLPBoundsPair[], _LinearNLPEvaluator(), false)
     end
     if !(:ExprGraph in MOI.features_available(nlp_block.evaluator))
         error(
diff --git a/src/Utilities/print.jl b/src/Utilities/print.jl
index 44f30f6d6d..d150a9291b 100644
--- a/src/Utilities/print.jl
+++ b/src/Utilities/print.jl
@@ -483,6 +483,9 @@ end
 function _nlp_block(model::MOI.ModelLike)
     try
         block = MOI.get(model, MOI.NLPBlock())
+        if block === nothing
+            return
+        end
         if :ExprGraph in MOI.features_available(block.evaluator)
             MOI.initialize(block.evaluator, [:ExprGraph])
         end

From 68f6ef617d2f7b79f97995c53c8bed2c21b96c57 Mon Sep 17 00:00:00 2001
From: odow <o.dowson@gmail.com>
Date: Fri, 29 Oct 2021 14:15:28 +1300
Subject: [PATCH 3/3] Fix

---
 src/FileFormats/NL/NL.jl | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/FileFormats/NL/NL.jl b/src/FileFormats/NL/NL.jl
index ff7a12cdcc..8cc160983d 100644
--- a/src/FileFormats/NL/NL.jl
+++ b/src/FileFormats/NL/NL.jl
@@ -243,10 +243,11 @@ MOI.initialize(::_LinearNLPEvaluator, ::Vector{Symbol}) = nothing
 function MOI.copy_to(dest::Model, model::MOI.ModelLike)
     mapping = MOI.Utilities.IndexMap()
     # Initialize the NLP block.
-    nlp_block = MOI.get(model, MOI.NLPBlock())
-    if nlp_block === nothing
-        nlp_block =
-            MOI.NLPBlockData(MOI.NLPBoundsPair[], _LinearNLPEvaluator(), false)
+    has_nlp = MOI.NLPBlock() in MOI.get(model, MOI.ListOfModelAttributesSet())
+    nlp_block = if has_nlp
+        MOI.get(model, MOI.NLPBlock())
+    else
+        MOI.NLPBlockData(MOI.NLPBoundsPair[], _LinearNLPEvaluator(), false)
     end
     if !(:ExprGraph in MOI.features_available(nlp_block.evaluator))
         error(