Throw clearer ArgumentError for strip with two string args (#51491)

(cherry picked from commit 66fe51f)

base/strings/util.jl

@@ -350,6 +350,7 @@ function lstrip(f, s::AbstractString)
 end
 lstrip(s::AbstractString) = lstrip(isspace, s)
 lstrip(s::AbstractString, chars::Chars) = lstrip(in(chars), s)
+lstrip(::AbstractString, ::AbstractString) = throw(ArgumentError("Both arguments are strings. The second argument should be a `Char` or collection of `Char`s"))
 
 """
     rstrip([pred=isspace,] str::AbstractString) -> SubString
@@ -383,6 +384,8 @@ function rstrip(f, s::AbstractString)
 end
 rstrip(s::AbstractString) = rstrip(isspace, s)
 rstrip(s::AbstractString, chars::Chars) = rstrip(in(chars), s)
+rstrip(::AbstractString, ::AbstractString) = throw(ArgumentError("Both arguments are strings. The second argument should be a `Char` or collection of `Char`s"))
+
 
 """
     strip([pred=isspace,] str::AbstractString) -> SubString
@@ -410,6 +413,7 @@ julia> strip("{3, 5}\\n", ['{', '}', '\\n'])
 """
 strip(s::AbstractString) = lstrip(rstrip(s))
 strip(s::AbstractString, chars::Chars) = lstrip(rstrip(s, chars), chars)
+strip(::AbstractString, ::AbstractString) = throw(ArgumentError("Both arguments are strings. The second argument should be a `Char` or collection of `Char`s"))
 strip(f, s::AbstractString) = lstrip(f, rstrip(f, s))
 
 ## string padding functions ##

test/strings/util.jl

@@ -89,6 +89,10 @@ end
     @test rstrip(isnumeric, "abc0123") == "abc"
     @test lstrip("ello", ['e','o']) == "llo"
     @test rstrip("ello", ['e','o']) == "ell"
+
+    @test_throws ArgumentError strip("", "")
+    @test_throws ArgumentError lstrip("", "")
+    @test_throws ArgumentError rstrip("", "")
 end
 
 @testset "partition" begin