add some helpful type information to Base and REPLCompletions (#34596)

fixes #34098

base/client.jl

@@ -427,7 +427,7 @@ using ..Base
 # include(fname::AbstractString) = Main.Base.include(Main, fname)
 function include(fname::AbstractString)
     mod = Main
-    isa(fname, String) || (fname = Base.convert(String, fname))
+    isa(fname, String) || (fname = Base.convert(String, fname)::String)
     path, prev = Base._include_dependency(mod, fname)
     for callback in Base.include_callbacks # to preserve order, must come before Core.include
         Base.invokelatest(callback, mod, path)

base/loading.jl

@@ -1086,8 +1086,8 @@ include_string(m::Module, txt::AbstractString, fname::AbstractString="string") =
 
 function source_path(default::Union{AbstractString,Nothing}="")
     s = current_task().storage
-    if s !== nothing && haskey(s, :SOURCE_PATH)
-        return s[:SOURCE_PATH]
+    if s !== nothing && haskey(s::IdDict{Any,Any}, :SOURCE_PATH)
+        return s[:SOURCE_PATH]::Union{Nothing,String}
     end
     return default
 end
@@ -1487,7 +1487,7 @@ Alternatively see [`PROGRAM_FILE`](@ref).
 """
 macro __FILE__()
     __source__.file === nothing && return nothing
-    return String(__source__.file)
+    return String(__source__.file::Symbol)
 end
 
 """
@@ -1499,6 +1499,6 @@ Return the current working directory if run from a REPL or if evaluated by `juli
 """
 macro __DIR__()
     __source__.file === nothing && return nothing
-    _dirname = dirname(String(__source__.file))
+    _dirname = dirname(String(__source__.file::Symbol))
     return isempty(_dirname) ? pwd() : abspath(_dirname)
 end

base/logging.jl

@@ -204,7 +204,7 @@ end
 macro _sourceinfo()
     esc(quote
         (__module__,
-         __source__.file === nothing ? "?" : String(__source__.file),
+         __source__.file === nothing ? "?" : String(__source__.file::Symbol),
          __source__.line)
     end)
 end

stdlib/REPL/src/REPLCompletions.jl

@@ -266,7 +266,7 @@ function complete_path(path::AbstractString, pos; use_envpath=false, shell_escap
         end
     end
 
-    matchList = Completion[PathCompletion(shell_escape ? replace(s, r"\s" => s"\\\0") : s) for s in matches]
+    matchList = PathCompletion[PathCompletion(shell_escape ? replace(s, r"\s" => s"\\\0") : s) for s in matches]
     startpos = pos - lastindex(prefix) + 1 - count(isequal(' '), prefix)
     # The pos - lastindex(prefix) + 1 is correct due to `lastindex(prefix)-lastindex(prefix)==0`,
     # hence we need to add one to get the first index. This is also correct when considering
@@ -544,7 +544,7 @@ end
 
 # This needs to be a separate non-inlined function, see #19441
 @noinline function find_dict_matches(identifier, partial_key)
-    matches = []
+    matches = String[]
     for key in keys(identifier)
         rkey = repr(key)
         startswith(rkey,partial_key) && push!(matches,rkey)