Provide Fx types before user types (#1191)

Consider the following example:
```go
func opts() fx.Option {
        return fx.Options(
                fx.WithLogger(func(fx.Lifecycle) fxevent.Logger {
                        return &fxevent.ConsoleLogger{ W: os.Stdout }
                }),
                fx.Provide(func() string { return "" }),
                fx.Provide(func() string { return "" }),
        )
}

func main() {
        fx.New(opts()).Run()
}
```

The relevant issue to surface to the user is that they are double
providing the same type. However, the actual error message is:
```
[Fx] ERROR              Failed to start: the following errors occurred:
 -  fx.Provide(main.opts.func3()) from:
    main.opts
        /home/user/go/src/scratch/fx_provide_order/main.go:17
    main.main
        /home/user/go/src/scratch/fx_provide_order/main.go:22
    runtime.main
        /opt/go/root/src/runtime/proc.go:271
    Failed: cannot provide function "main".opts.func3
(/home/user/go/src/scratch/fx_provide_order/main.go:17): cannot provide
string from [0]: already provided by "main".opts.func2
(/home/user/go/src/scratch/fx_provide_order/main.go:16)
 -  could not build arguments for function
"go.uber.org/fx".(*module).constructCustomLogger.func2
        /home/user/go-repos/pkg/mod/go.uber.org/[email protected]/module.go:292:
    failed to build fxevent.Logger:
    missing dependencies for function "main".opts.func1
        /home/user/go/src/scratch/fx_provide_order/main.go:11:
    missing type:
        - fx.Lifecycle (did you mean to Provide it?)
```
Which contains an additional error related to how the custom logger
could not be built.

This is because Fx will try to continue to build the custom logger in
the face of DI failure, theoretically to report issues through the right
channels. But after an error occurs when providing anything, [Fx refuses
to provide any more
types](https://github.com/uber-go/fx/blob/master/module.go#L184) -
leading to a subsequent error when trying to build this custom logger
that depends on the `fx.Lifecycle` type.

This is a common issue that can be misleading for new engineers
debugging their fx apps.

I couldn't find any particular reason why user-provided provides are
registered before these Fx types, so this PR switches this ordering so
that custom loggers can still be built if they rely on the Fx types,
which cleans up the error message:
```
[Fx] ERROR              Failed to start: fx.Provide(main.opts.func3())
from:
main.opts
        /home/user/go/src/scratch/fx_provide_order/main.go:17
main.main
        /home/user/go/src/scratch/fx_provide_order/main.go:22
runtime.main
        /opt/go/root/src/runtime/proc.go:271
Failed: cannot provide function "main".opts.func3
(/home/user/go/src/scratch/fx_provide_order/main.go:17): cannot provide
string from [0]: already provided by "main".opts.func2
(/home/user/go/src/scratch/fx_provide_order/main.go:16)
```

Author: JacobOaks

app.go

@@ -480,10 +480,9 @@ func New(opts ...Option) *App {
 		m.build(app, app.container)
 	}
 
-	for _, m := range app.modules {
-		m.provideAll()
-	}
-
+	// Provide Fx types first to increase the chance a custom logger
+	// can be successfully built in the face of unrelated DI failure.
+	// E.g., for a custom logger that relies on the Lifecycle type.
 	frames := fxreflect.CallerStack(0, 0) // include New in the stack for default Provides
 	app.root.provide(provide{
 		Target: func() Lifecycle { return app.lifecycle },
@@ -492,6 +491,10 @@ func New(opts ...Option) *App {
 	app.root.provide(provide{Target: app.shutdowner, Stack: frames})
 	app.root.provide(provide{Target: app.dotGraph, Stack: frames})
 
+	for _, m := range app.modules {
+		m.provideAll()
+	}
+
 	// Run decorators before executing any Invokes -- including the one
 	// inside constructCustomLogger.
 	app.err = multierr.Append(app.err, app.root.decorateAll())

app_test.go

@@ -113,7 +113,13 @@ func TestNewApp(t *testing.T) {
 			[]string{"Provided", "Provided", "Provided", "Provided", "LoggerInitialized", "Started"},
 			spy.EventTypes())
 
-		assert.Contains(t, spy.Events()[0].(*fxevent.Provided).OutputTypeNames, "struct {}")
+		// Fx types get provided first to increase chance of
+		// successful custom logger build.
+		assert.Contains(t, spy.Events()[0].(*fxevent.Provided).OutputTypeNames, "fx.Lifecycle")
+		assert.Contains(t, spy.Events()[1].(*fxevent.Provided).OutputTypeNames, "fx.Shutdowner")
+		assert.Contains(t, spy.Events()[2].(*fxevent.Provided).OutputTypeNames, "fx.DotGraph")
+		// Our type should be index 3.
+		assert.Contains(t, spy.Events()[3].(*fxevent.Provided).OutputTypeNames, "struct {}")
 	})
 
 	t.Run("CircularGraphReturnsError", func(t *testing.T) {
@@ -575,7 +581,7 @@ func TestWithLogger(t *testing.T) {
 		)
 
 		assert.Equal(t, []string{
-			"Supplied", "Provided", "Provided", "Provided", "Run", "LoggerInitialized",
+			"Provided", "Provided", "Provided", "Supplied", "Run", "LoggerInitialized",
 		}, spy.EventTypes())
 
 		spy.Reset()
@@ -605,7 +611,7 @@ func TestWithLogger(t *testing.T) {
 			"must provide constructor function, got  (type *bytes.Buffer)",
 		)
 
-		assert.Equal(t, []string{"Supplied", "Provided", "Run", "LoggerInitialized"}, spy.EventTypes())
+		assert.Equal(t, []string{"Provided", "Provided", "Provided", "Supplied", "Provided", "Run", "LoggerInitialized"}, spy.EventTypes())
 	})
 
 	t.Run("logger failed to build", func(t *testing.T) {
@@ -1166,8 +1172,9 @@ func TestOptions(t *testing.T) {
 			Provide(&bytes.Buffer{}), // error, not a constructor
 			WithLogger(func() fxevent.Logger { return spy }),
 		)
-		require.Equal(t, []string{"Provided", "LoggerInitialized"}, spy.EventTypes())
-		assert.Contains(t, spy.Events()[0].(*fxevent.Provided).Err.Error(), "must provide constructor function")
+		require.Equal(t, []string{"Provided", "Provided", "Provided", "Provided", "LoggerInitialized"}, spy.EventTypes())
+		// First 3 provides are Fx types (Lifecycle, Shutdowner, DotGraph).
+		assert.Contains(t, spy.Events()[3].(*fxevent.Provided).Err.Error(), "must provide constructor function")
 	})
 }
 

module_test.go

@@ -261,15 +261,15 @@ func TestModuleSuccess(t *testing.T) {
 				desc:           "custom logger for module",
 				giveWithLogger: fx.NopLogger,
 				wantEvents: []string{
-					"Supplied", "Provided", "Provided", "Provided",
+					"Provided", "Provided", "Provided", "Supplied",
 					"Run", "LoggerInitialized", "Invoking", "Invoked",
 				},
 			},
 			{
 				desc:           "Not using a custom logger for module defaults to app logger",
 				giveWithLogger: fx.Options(),
 				wantEvents: []string{
-					"Supplied", "Provided", "Provided", "Provided", "Provided", "Run",
+					"Provided", "Provided", "Provided", "Supplied", "Provided", "Run",
 					"LoggerInitialized", "Invoking", "Run", "Invoked", "Invoking", "Invoked",
 				},
 			},
@@ -660,7 +660,7 @@ func TestModuleFailures(t *testing.T) {
 				giveAppOpts:     spyAsLogger,
 				wantErrContains: []string{"error building logger"},
 				wantEvents: []string{
-					"Supplied", "Provided", "Provided", "Provided", "Run",
+					"Provided", "Provided", "Provided", "Supplied", "Run",
 					"LoggerInitialized", "Provided", "LoggerInitialized",
 				},
 			},
@@ -678,7 +678,7 @@ func TestModuleFailures(t *testing.T) {
 				giveAppOpts:     spyAsLogger,
 				wantErrContains: []string{"error building logger dependency"},
 				wantEvents: []string{
-					"Supplied", "Provided", "Provided", "Provided", "Run",
+					"Provided", "Provided", "Provided", "Supplied", "Run",
 					"LoggerInitialized", "Provided", "Provided", "Run", "LoggerInitialized",
 				},
 			},
@@ -690,7 +690,7 @@ func TestModuleFailures(t *testing.T) {
 					"fx.WithLogger", "from:", "Failed",
 				},
 				wantEvents: []string{
-					"Supplied", "Provided", "Provided", "Provided", "Run",
+					"Provided", "Provided", "Provided", "Supplied", "Run",
 					"LoggerInitialized", "Provided", "LoggerInitialized",
 				},
 			},