check if cachefile dependencies can be fulfilled

Author: vchuravy

base/loading.jl

@@ -699,7 +699,16 @@ function parse_cache_header(f::IO)
         push!(files, (String(read(f, n)), ntoh(read(f, Float64))))
     end
     @assert totbytes == 4 "header of cache file appears to be corrupt"
-    return modules, files
+    # read the list of modules that are required to be present during loading
+    required_modules = Dict{Symbol, UInt64}()
+    while true
+        n = ntoh(read(f, Int32))
+        n == 0 && break
+        sym = Symbol(read(f, n)) # module symbol
+        uuid = ntoh(read(f, UInt64)) # module UUID
+        required_modules[sym] = uuid
+    end
+    return modules, files, required_modules
 end
 
 function parse_cache_header(cachefile::String)
@@ -713,15 +722,7 @@ function parse_cache_header(cachefile::String)
 end
 
 function cache_dependencies(f::IO)
-    defs, files = parse_cache_header(f)
-    modules = []
-    while true
-        n = ntoh(read(f, Int32))
-        n == 0 && break
-        sym = Symbol(read(f, n)) # module symbol
-        uuid = ntoh(read(f, UInt64)) # module UUID (mostly just a timestamp)
-        push!(modules, (sym, uuid))
-    end
+    defs, files, modules = parse_cache_header(f)
     return modules, files
 end
 
@@ -742,7 +743,22 @@ function stale_cachefile(modpath::String, cachefile::String)
             DEBUG_LOADING[] && info("JL_DEBUG_LOADING: Rejecting cache file $cachefile due to it containing an invalid cache header.")
             return true # invalid cache file
         end
-        modules, files = parse_cache_header(io)
+        modules, files, required_modules = parse_cache_header(io)
+
+        # Check if transitive dependencies can be fullfilled
+        for mod in keys(required_modules)
+            if mod == :Main || mod == :Core || mod == :Base
+                continue
+            # Module is already loaded
+            elseif isdefined(Main, mod)
+                continue
+            end
+            name = string(mod)
+            path = find_in_node_path(name, nothing, 1)
+            if path === nothing
+                return true # Won't be able to fullfill dependency
+            end
+        end
 
         # check if this file is going to provide one of our concrete dependencies
         # or if it provides a version that conflicts with our concrete dependencies

test/compile.jl

@@ -184,13 +184,13 @@ try
         @test stringmime("text/plain", Base.Docs.doc(Foo.foo)) == "foo function\n"
         @test stringmime("text/plain", Base.Docs.doc(Foo.Bar.bar)) == "bar function\n"
 
-        modules, deps = Base.parse_cache_header(cachefile)
+        modules, deps, required_modules = Base.parse_cache_header(cachefile)
         @test modules == Dict(Foo_module => Base.module_uuid(Foo))
         @test map(x -> x[1],  sort(deps)) == [Foo_file, joinpath(dir, "bar.jl"), joinpath(dir, "foo.jl")]
 
         modules, deps1 = Base.cache_dependencies(cachefile)
-        @test sort(modules) == Any[(s, Base.module_uuid(getfield(Foo, s))) for s in
-                                   [:Base, :Core, Foo2_module, FooBase_module, :Main]]
+        @test modules == Dict(s => Base.module_uuid(getfield(Foo, s)) for s in
+                                    [:Base, :Core, Foo2_module, FooBase_module, :Main])
         @test deps == deps1
 
         @test current_task()(0x01, 0x4000, 0x30031234) == 2