diff --git a/src/gf.c b/src/gf.c
index 27a7d85e5a4c4..b3ef5221105e0 100644
--- a/src/gf.c
+++ b/src/gf.c
@@ -1276,7 +1276,15 @@ static void method_overwrite(jl_typemap_entry_t *newentry, jl_method_t *oldvalue
     if ((jl_options.warn_overwrite == JL_OPTIONS_WARN_OVERWRITE_ON) ||
         (jl_options.incremental && jl_generating_output()) || anon) {
         JL_STREAM *s = JL_STDERR;
-        jl_printf(s, "WARNING: Method definition ");
+        ios_t memstream;
+        if (anon) {
+            ios_mem(&memstream, 300);
+            s = (JL_STREAM*)&memstream;
+        }
+        else {
+            jl_printf(s, "WARNING: ");
+        }
+        jl_printf(s, "Method definition ");
         jl_static_show_func_sig(s, (jl_value_t*)newentry->sig);
         jl_printf(s, " in module %s", jl_symbol_name(oldmod->name));
         print_func_loc(s, oldvalue);
@@ -1287,7 +1295,13 @@ static void method_overwrite(jl_typemap_entry_t *newentry, jl_method_t *oldvalue
             jl_printf(s, anon ? " on the same line" : " on the same line (check for duplicate calls to `include`)");
         else
             print_func_loc(s, method);
-        jl_printf(s, ".\n");
+        jl_printf(s, ".");
+        if (anon) {
+            jl_value_t *msg = jl_pchar_to_string(memstream.buf, memstream.size);
+            JL_GC_PUSH1(&msg);
+            jl_throw(jl_new_struct(jl_errorexception_type, msg));
+        }
+        jl_printf(s, "\n");
         jl_uv_flush(s);
     }
     if (jl_options.incremental && jl_generating_output())
diff --git a/test/misc.jl b/test/misc.jl
index 76be4e036dd5c..2b088046add62 100644
--- a/test/misc.jl
+++ b/test/misc.jl
@@ -86,18 +86,25 @@ let
         $redir_err
         module A; f() = 1; end; A.f() = 1
         A.f() = 1
-        outer() = (g() = 1; g() = 2; g)
         """
     warning_str = read(`$exename --warn-overwrite=yes --startup-file=no -e $script`, String)
     @test warning_str == """
         WARNING: Method definition f() in module A at none:2 overwritten in module Main on the same line (check for duplicate calls to `include`).
         WARNING: Method definition f() in module Main at none:2 overwritten at none:3.
-        WARNING: Method definition g() in module Main at none:4 overwritten on the same line.
         """
     warning_str = read(`$exename --startup-file=no -e $script`, String)
-    @test warning_str == """
-        WARNING: Method definition g() in module Main at none:4 overwritten on the same line.
-        """
+    @test warning_str == ""
+end
+
+# Overriding closure methods is an error (#15602)
+let g_line = (@__LINE__) + 3,
+    closure_method_overwrite =
+        :(function closure_method_overrwrite_g()
+              g() = 1
+              g() = 2
+          end)
+    @test_throws ErrorException("Method definition g() in module $(nameof(@__MODULE__)) at $(@__FILE__):$g_line overwritten at $(@__FILE__):$(g_line+1).") #=
+        =# eval(closure_method_overwrite)
 end
 
 # Debugging tool: return the current state of the enable_finalizers counter.
diff --git a/test/specificity.jl b/test/specificity.jl
index de65c289be02a..dc480adbee850 100644
--- a/test/specificity.jl
+++ b/test/specificity.jl
@@ -81,19 +81,15 @@ _bound_vararg_specificity_1(::Type{Array{T,1}}, d::Int) where {T} = 1
 @test args_morespecific(Tuple{Matrix}, Tuple{AbstractVector})
 
 # Method specificity
-begin
-    local f, A
-    f(dims::Tuple{}, A::AbstractArray{T,0}) where {T} = 1
-    f(dims::NTuple{N,Int}, A::AbstractArray{T,N}) where {T,N} = 2
-    f(dims::NTuple{M,Int}, A::AbstractArray{T,N}) where {T,M,N} = 3
-    A = zeros(2,2)
-    @test f((1,2,3), A) == 3
-    @test f((1,2), A) == 2
-    @test f((), reshape([1])) == 1
-    f(dims::NTuple{N,Int}, A::AbstractArray{T,N}) where {T,N} = 4
-    @test f((1,2), A) == 4
-    @test f((1,2,3), A) == 3
-end
+f22162(dims::Tuple{}, A::AbstractArray{T,0}) where {T} = 1
+f22162(dims::NTuple{N,Int}, A::AbstractArray{T,N}) where {T,N} = 2
+f22162(dims::NTuple{M,Int}, A::AbstractArray{T,N}) where {T,M,N} = 3
+@test f22162((1,2,3), zeros(2,2)) == 3
+@test f22162((1,2), zeros(2,2)) == 2
+@test f22162((), reshape([1])) == 1
+f22162(dims::NTuple{N,Int}, A::AbstractArray{T,N}) where {T,N} = 4
+@test f22162((1,2), zeros(2,2)) == 4
+@test f22162((1,2,3), zeros(2,2)) == 3
 
 # a method specificity issue
 c99991(::Type{T},x::T) where {T} = 0
diff --git a/test/tuple.jl b/test/tuple.jl
index 768a1050c09c0..5e5b379ade085 100644
--- a/test/tuple.jl
+++ b/test/tuple.jl
@@ -607,9 +607,9 @@ f38837(xs) = map((F,x)->F(x), (Float32, Float64), xs)
     @test @inferred(f(Tuple(1:10))) === Tuple(3:8)
     @test @inferred(f((true, 2., 3, 4f0, 0x05, 6, 7.))) === (3, 4f0, 0x05)
 
-    f(t) = t[Base.OneTo(5)]
-    @test @inferred(f(Tuple(1:10))) === Tuple(1:5)
-    @test @inferred(f((true, 2., 3, 4f0, 0x05, 6, 7.))) === (true, 2., 3, 4f0, 0x05)
+    g(t) = t[Base.OneTo(5)]
+    @test @inferred(g(Tuple(1:10))) === Tuple(1:5)
+    @test @inferred(g((true, 2., 3, 4f0, 0x05, 6, 7.))) === (true, 2., 3, 4f0, 0x05)
 
     @test @inferred((t -> t[1:end])(Tuple(1:15))) === Tuple(1:15)
     @test @inferred((t -> t[2:end])(Tuple(1:15))) === Tuple(2:15)