Compare 'nothing' using === in more places (#2933)

src/Combinatorics/Matroids/matroids.jl

@@ -43,7 +43,7 @@ Matroid of rank 3 on 7 elements
 ```
 """
 function matroid_from_revlex_basis_encoding(rvlx::String, r::IntegerUnion, n::IntegerUnion)
-    if match(r"[^*0]",rvlx)!=nothing
+    if match(r"[^*0]",rvlx) !== nothing
         error("The revlex encoding uses only `*` and `0`")
     end
     if length(rvlx)!= binomial(n,r)

src/Combinatorics/Matroids/properties.jl

@@ -161,7 +161,7 @@ function flats_impl(M::Matroid, r::Union{Int,Nothing}, num_flats::Int, pm_flats)
         jl_flats = reverse(jl_flats)
     end
     matroid_flats = [[M.groundset[i] for i in flat] for flat in jl_flats]
-    if r != nothing
+    if r !== nothing
         if r<0 || r>rank(M)
             error("The specified rank needs to be between 0 and the rank of the matroid.")
         end

src/Groups/matrices/MatGrp.jl

@@ -305,7 +305,9 @@ Base.in(x::MatElem, G::MatrixGroup) = lies_in(x,G,nothing)[1]
 function Base.in(x::MatrixGroupElem, G::MatrixGroup)
    isdefined(x,:X) && return lies_in(x.elm,G,x.X)[1]
    _is_true, x_gap = lies_in(x.elm,G,nothing)
-   if x_gap !=nothing x.X = x_gap end
+   if x_gap !== nothing
+      x.X = x_gap
+   end
    return _is_true
 end
 
@@ -340,7 +342,7 @@ function (G::MatrixGroup)(x::MatrixGroupElem; check::Bool=true)
    else
       _is_true, x_gap = lies_in(x.elm,G,nothing)
       @req _is_true "Element not in the group"
-      if x_gap == nothing
+      if x_gap === nothing
         return MatrixGroupElem(G,x.elm)
       end
       return MatrixGroupElem(G,x.elm,x_gap)

src/Modules/ModulesGraded.jl

@@ -1374,7 +1374,7 @@ function Base.show(io::IO, b::BettiTable)
     column_widths[j] = max(col_width_from_sum, col_width_from_header) + 2
   end
 
-  if b.project == nothing
+  if b.project === nothing
     for i in 1:ngens(parent(x[1][2]))
       ngens(parent(x[1][2])) > 1 && println(io, "Betti Table for component ", i)
       L = sort(unique(collect(x[k][2][i] for k in 1:length(x))))

src/TropicalGeometry/groebner_fan.jl

@@ -114,7 +114,7 @@ julia> G3 = [x1^2+x2,x2^2+x3,x3+1]
  x2^2 + x3
  x3 + 1
 
-julia> homogeneity_vector(G3) == nothing
+julia> homogeneity_vector(G3) === nothing
 true
 
 ```