fix parse(ComplexF64, "inf")

(cherry picked from commit c36e70b)

Author: stevengj

base/parse.jl

@@ -309,7 +309,7 @@ function tryparse_internal(::Type{Complex{T}}, s::Union{String,SubString{String}
     end
 
     if i₊ == 0 # purely real or imaginary value
-        if iᵢ > 0 # purely imaginary
+        if iᵢ > i && !(iᵢ == i+1 && s[i] in ('+','-')) # purely imaginary (not "±inf")
             x = tryparse_internal(T, s, i, iᵢ-1, raise)
             x === nothing && return nothing
             return Complex{T}(zero(x),x)

test/parse.jl

@@ -268,8 +268,8 @@ end
 
 # parsing complex numbers (#22250)
 @testset "complex parsing" begin
-    for r in (1,0,-1), i in (1,0,-1), sign in ('-','+'), Im in ("i","j","im")
-        for s1 in (""," "), s2 in (""," "), s3 in (""," "), s4 in (""," ")
+    for sign in ('-','+'), Im in ("i","j","im"), s1 in (""," "), s2 in (""," "), s3 in (""," "), s4 in (""," ")
+        for r in (1,0,-1), i in (1,0,-1),
             n = Complex(r, sign == '+' ? i : -i)
             s = string(s1, r, s2, sign, s3, i, Im, s4)
             @test n === parse(Complex{Int}, s)
@@ -283,6 +283,13 @@ end
                 @test n*parse(T,"1e-3") == parse(Complex{T}, string(s1, r, "e-3", s2, sign, s3, i, "e-3", Im, s4))
             end
         end
+        for r in (-1.0,-1e-9,Inf,-Inf,NaN), i in (-1.0,-1e-9,Inf,NaN)
+            n = Complex(r, sign == '+' ? i : -i)
+            s = lowercase(string(s1, r, s2, sign, s3, i, Im, s4))
+            @test n === parse(ComplexF64, s)
+            @test Complex(r) === parse(ComplexF64, string(s1, r, s2))
+            @test Complex(0,i) === parse(ComplexF64, string(s3, i, Im, s4))
+        end
     end
     @test parse(Complex{Float16}, "3.3+4i") === Complex{Float16}(3.3+4im)
     @test parse(Complex{Int}, SubString("xxxxxx1+2imxxxx", 7, 10)) === 1+2im