[FileFormats.NL] fix reading defined variables that are not expressions (#2980)

Author: odow

src/FileFormats/NL/read.jl

@@ -17,7 +17,7 @@ mutable struct _CacheModel
     objective::Expr
     sense::MOI.OptimizationSense
     complements_map::Dict{Int,Int}
-    defined_variables::Dict{Int,Expr}
+    defined_variables::Dict{Int,Union{Float64,MOI.VariableIndex,Expr}}
 
     function _CacheModel()
         return new(
@@ -33,7 +33,7 @@ mutable struct _CacheModel
             :(),
             MOI.FEASIBILITY_SENSE,
             Dict{Int,Int}(),
-            Dict{Int,Expr}(),
+            Dict{Int,Union{Float64,MOI.VariableIndex,Expr}}(),
         )
     end
 end

test/FileFormats/NL/test_read.jl

@@ -551,6 +551,27 @@ function test_parse_V()
     return
 end
 
+function test_parse_V_constant()
+    model = NL._CacheModel()
+    io = IOBuffer("V2 0 0\nn0\n")
+    seekstart(io)
+    NL._parse_section(io, model)
+    @test length(model.defined_variables) == 1
+    @test model.defined_variables[2] === 0.0
+    return
+end
+
+function test_parse_V_variable()
+    model = NL._CacheModel()
+    NL._resize_variables(model, 2)
+    io = IOBuffer("V1 0 0\nv0\n")
+    seekstart(io)
+    NL._parse_section(io, model)
+    @test length(model.defined_variables) == 1
+    @test model.defined_variables[1] === MOI.VariableIndex(1)
+    return
+end
+
 function test_parse_L()
     model = NL._CacheModel()
     io = IOBuffer()