remove bad method specialization from cache (#39429)

This was inserting a method with signature [Int, Int], rather than
Tuple{typeof(+), Int, Int}. Fix that and add a test for it so it doesn't
happen again.

base/Base.jl

@@ -394,37 +394,36 @@ in_sysimage(pkgid::PkgId) = pkgid in _sysimage_modules
 # Precompiles for Revise
 # TODO: move these to contrib/generate_precompile.jl
 # The problem is they don't work there
-let m = which(+, (Int, Int))
-    while true  # defeat interpreter heuristic to force compilation
-        delete!(push!(Set{Method}(), m), m)
-        copy(Core.Compiler.retrieve_code_info(Core.Compiler.specialize_method(m, [Int, Int], Core.svec())))
-
-        empty!(Set())
-        push!(push!(Set{Union{GlobalRef,Symbol}}(), :two), GlobalRef(Base, :two))
-        (setindex!(Dict{String,Base.PkgId}(), Base.PkgId(Base), "file.jl"))["file.jl"]
-        (setindex!(Dict{Symbol,Vector{Int}}(), [1], :two))[:two]
-        (setindex!(Dict{Base.PkgId,String}(), "file.jl", Base.PkgId(Base)))[Base.PkgId(Base)]
-        (setindex!(Dict{Union{GlobalRef,Symbol}, Vector{Int}}(), [1], :two))[:two]
-        (setindex!(IdDict{Type, Union{Missing, Vector{Tuple{LineNumberNode, Expr}}}}(), missing, Int))[Int]
-        Dict{Symbol, Union{Nothing, Bool, Symbol}}(:one => false)[:one]
-        Dict(Base => [:(1+1)])[Base]
-        Dict(:one => [1])[:one]
-        Dict("abc" => Set())["abc"]
-        pushfirst!([], sum)
-        get(Base.pkgorigins, Base.PkgId(Base), nothing)
-        sort!([1,2,3])
-        unique!([1,2,3])
-        cumsum([1,2,3])
-        append!(Int[], BitSet())
-        isempty(BitSet())
-        delete!(BitSet([1,2]), 3)
-        deleteat!(Int32[1,2,3], [1,3])
-        deleteat!(Any[1,2,3], [1,3])
-        Core.svec(1, 2) == Core.svec(3, 4)
-        any(t->t[1].line > 1, [(LineNumberNode(2,:none), :(1+1))])
-
-        break   # end defeat interpreter heuristic
-    end
+for match = _methods(+, (Int, Int), -1, get_world_counter())
+    m = match.method
+    delete!(push!(Set{Method}(), m), m)
+    copy(Core.Compiler.retrieve_code_info(Core.Compiler.specialize_method(match)))
+
+    empty!(Set())
+    push!(push!(Set{Union{GlobalRef,Symbol}}(), :two), GlobalRef(Base, :two))
+    (setindex!(Dict{String,Base.PkgId}(), Base.PkgId(Base), "file.jl"))["file.jl"]
+    (setindex!(Dict{Symbol,Vector{Int}}(), [1], :two))[:two]
+    (setindex!(Dict{Base.PkgId,String}(), "file.jl", Base.PkgId(Base)))[Base.PkgId(Base)]
+    (setindex!(Dict{Union{GlobalRef,Symbol}, Vector{Int}}(), [1], :two))[:two]
+    (setindex!(IdDict{Type, Union{Missing, Vector{Tuple{LineNumberNode, Expr}}}}(), missing, Int))[Int]
+    Dict{Symbol, Union{Nothing, Bool, Symbol}}(:one => false)[:one]
+    Dict(Base => [:(1+1)])[Base]
+    Dict(:one => [1])[:one]
+    Dict("abc" => Set())["abc"]
+    pushfirst!([], sum)
+    get(Base.pkgorigins, Base.PkgId(Base), nothing)
+    sort!([1,2,3])
+    unique!([1,2,3])
+    cumsum([1,2,3])
+    append!(Int[], BitSet())
+    isempty(BitSet())
+    delete!(BitSet([1,2]), 3)
+    deleteat!(Int32[1,2,3], [1,3])
+    deleteat!(Any[1,2,3], [1,3])
+    Core.svec(1, 2) == Core.svec(3, 4)
+    any(t->t[1].line > 1, [(LineNumberNode(2,:none), :(1+1))])
+
+    break   # only actually need to do this once
 end
 
 if is_primary_base_module

src/gf.c

@@ -104,7 +104,9 @@ static int speccache_eq(size_t idx, const void *ty, jl_svec_t *data, uint_t hv)
 // get or create the MethodInstance for a specialization
 JL_DLLEXPORT jl_method_instance_t *jl_specializations_get_linfo(jl_method_t *m JL_PROPAGATES_ROOT, jl_value_t *type, jl_svec_t *sparams)
 {
-    uint_t hv = ((jl_datatype_t*)(jl_is_unionall(type) ? jl_unwrap_unionall(type) : type))->hash;
+    jl_value_t *ut = jl_is_unionall(type) ? jl_unwrap_unionall(type) : type;
+    JL_TYPECHK(specializations, datatype, ut);
+    uint_t hv = ((jl_datatype_t*)ut)->hash;
     for (int locked = 0; ; locked++) {
         jl_array_t *speckeyset = jl_atomic_load_acquire(&m->speckeyset);
         jl_svec_t *specializations = jl_atomic_load_acquire(&m->specializations);