Implement eval-able AnnotatedString 2-arg show (#54308)

The generic/fallback AbstractString 2-arg show omits the annotations,
meaning that eval(Meta.parse(repr(::AnnotatedString))) doesn't
round-trip.

The resolution to this is fairly simple, we just need to implement a
specialised show method. The implementation is fairly obvious, we're
just also able to get away with hiding the vector type annotation since
the constructor is fine without it.

(cherry picked from commit cc26f4a)

Author: tecosaur

base/strings/annotated.jl

@@ -159,6 +159,22 @@ function getindex(s::AnnotatedString, i::Integer)
     end
 end
 
+# To make `AnnotatedString`s repr-evaluable, we need to override
+# the generic `AbstractString` 2-arg show method.
+
+function show(io::IO, s::A) where {A <: AnnotatedString}
+    show(io, A)
+    print(io, '(')
+    show(io, s.string)
+    print(io, ", ")
+    show(IOContext(io, :typeinfo => typeof(annotations(s))), annotations(s))
+    print(io, ')')
+end
+
+# But still use the generic `AbstractString` fallback for the 3-arg show.
+show(io::IO, ::MIME"text/plain", s::AnnotatedString) =
+    invoke(show, Tuple{IO, AbstractString}, io, s)
+
 ## AbstractChar interface ##
 
 ncodeunits(c::AnnotatedChar) = ncodeunits(c.char)

test/strings/annotated.jl

@@ -58,6 +58,10 @@
                              (3:3, :val => 2)])),
              Base.AnnotatedString("abc", [(1:2, :val => 1),
                                   (2:3, :val => 2)]))
+    @test chopprefix(sprint(show, str), "Base.") ==
+        "AnnotatedString{String}(\"some string\", [(1:4, :thing => 0x01), (1:11, :all => 0x03), (6:11, :other => 0x02)])"
+    @test eval(Meta.parse(repr(str))) == str
+    @test sprint(show, MIME("text/plain"), str) == "\"some string\""
 end
 
 @testset "AnnotatedChar" begin