wire: give wire.Bind access to the arguments to the injector function (google/go-cloud#715)

cmd/wire/main.go

@@ -238,6 +238,9 @@ func gather(info *wire.Info, key wire.ProviderSetID) (_ []outGroup, imports map[
 			case pv.IsNil():
 				// This is an input.
 				inputVisited.Set(curr, -1)
+			case pv.IsArg():
+				// This is an injector argument.
+				inputVisited.Set(curr, -1)
 			case pv.IsProvider():
 				// Try to see if any args haven't been visited.
 				p := pv.Provider()

internal/wire/analyze.go

@@ -80,37 +80,14 @@ type call struct {
 
 // solve finds the sequence of calls required to produce an output type
 // with an optional set of provided inputs.
-func solve(fset *token.FileSet, out types.Type, given []types.Type, set *ProviderSet) ([]call, []error) {
+func solve(fset *token.FileSet, out types.Type, given *types.Tuple, set *ProviderSet) ([]call, []error) {
 	ec := new(errorCollector)
-	for i, g := range given {
-		for _, h := range given[:i] {
-			if types.Identical(g, h) {
-				ec.add(fmt.Errorf("multiple inputs of the same type %s", types.TypeString(g, nil)))
-			}
-		}
-	}
 
 	// Start building the mapping of type to local variable of the given type.
 	// The first len(given) local variables are the given types.
 	index := new(typeutil.Map)
-	for i, g := range given {
-		if pv := set.For(g); !pv.IsNil() {
-			switch {
-			case pv.IsProvider():
-				ec.add(fmt.Errorf("input of %s conflicts with provider %s at %s",
-					types.TypeString(g, nil), pv.Provider().Name, fset.Position(pv.Provider().Pos)))
-			case pv.IsValue():
-				ec.add(fmt.Errorf("input of %s conflicts with value at %s",
-					types.TypeString(g, nil), fset.Position(pv.Value().Pos)))
-			default:
-				panic("unknown return value from ProviderSet.For")
-			}
-		} else {
-			index.Set(g, i)
-		}
-	}
-	if len(ec.errors) > 0 {
-		return nil, ec.errors
+	for i := 0; i < given.Len(); i++ {
+		index.Set(given.At(i).Type(), i)
 	}
 
 	// Topological sort of the directed graph defined by the providers
@@ -149,6 +126,19 @@ dfs:
 			ec.add(errors.New(sb.String()))
 			index.Set(curr.t, errAbort)
 			continue
+		case pv.IsArg():
+			src := set.srcMap.At(curr.t).(*providerSetSrc)
+			used = append(used, src)
+			if concrete := pv.ConcreteType(); !types.Identical(concrete, curr.t) {
+				// Interface binding.
+				i := index.At(concrete)
+				if i == nil {
+					stk = append(stk, curr, frame{t: concrete, from: curr.t, up: &curr})
+					continue
+				}
+				index.Set(curr.t, i)
+			}
+			continue
 		case pv.IsProvider():
 			p := pv.Provider()
 			src := set.srcMap.At(curr.t).(*providerSetSrc)
@@ -192,7 +182,7 @@ dfs:
 				}
 				args[i] = v.(int)
 			}
-			index.Set(curr.t, len(given)+len(calls))
+			index.Set(curr.t, given.Len()+len(calls))
 			kind := funcProviderCall
 			if p.IsStruct {
 				kind = structProvider
@@ -222,7 +212,7 @@ dfs:
 			}
 			src := set.srcMap.At(curr.t).(*providerSetSrc)
 			used = append(used, src)
-			index.Set(curr.t, len(given)+len(calls))
+			index.Set(curr.t, given.Len()+len(calls))
 			calls = append(calls, call{
 				kind:          valueExpr,
 				out:           curr.t,
@@ -308,8 +298,23 @@ func buildProviderMap(fset *token.FileSet, hasher typeutil.Hasher, set *Provider
 	srcMap := new(typeutil.Map) // to *providerSetSrc
 	srcMap.SetHasher(hasher)
 
-	// Process imports first, verifying that there are no conflicts between sets.
 	ec := new(errorCollector)
+	// Process injector arguments.
+	if set.InjectorArgs != nil {
+		givens := set.InjectorArgs.Tuple
+		for i := 0; i < givens.Len(); i++ {
+			typ := givens.At(i).Type()
+			arg := &InjectorArg{Args: set.InjectorArgs, Index: i}
+			src := &providerSetSrc{InjectorArg: arg}
+			if prevSrc := srcMap.At(typ); prevSrc != nil {
+				ec.add(bindingConflictError(fset, typ, set, src, prevSrc.(*providerSetSrc)))
+				continue
+			}
+			providerMap.Set(typ, &ProvidedType{t: typ, a: arg})
+			srcMap.Set(typ, src)
+		}
+	}
+	// Process imports, verifying that there are no conflicts between sets.
 	for _, imp := range set.Imports {
 		src := &providerSetSrc{Import: imp}
 		imp.providerMap.Iterate(func(k types.Type, v interface{}) {
@@ -407,6 +412,10 @@ func verifyAcyclic(providerMap *typeutil.Map, hasher typeutil.Hasher) []error {
 				// Leaf: values do not have dependencies.
 				continue
 			}
+			if pt.IsArg() {
+				// Injector arguments do not have dependencies.
+				continue
+			}
 			if !pt.IsProvider() {
 				panic("invalid provider map value")
 			}

internal/wire/parse.go

@@ -36,6 +36,7 @@ type providerSetSrc struct {
 	Binding     *IfaceBinding
 	Value       *Value
 	Import      *ProviderSet
+	InjectorArg *InjectorArg
 }
 
 // description returns a string describing the source of p, including line numbers.
@@ -59,6 +60,9 @@ func (p *providerSetSrc) description(fset *token.FileSet, typ types.Type) string
 		return fmt.Sprintf("wire.Value (%s)", fset.Position(p.Value.Pos))
 	case p.Import != nil:
 		return fmt.Sprintf("provider set %s(%s)", quoted(p.Import.VarName), fset.Position(p.Import.Pos))
+	case p.InjectorArg != nil:
+		args := p.InjectorArg.Args
+		return fmt.Sprintf("argument %s to injector function %s (%s)", args.Tuple.At(p.InjectorArg.Index).Name(), args.Name, fset.Position(args.Pos))
 	}
 	panic("providerSetSrc with no fields set")
 }
@@ -93,6 +97,8 @@ type ProviderSet struct {
 	Bindings  []*IfaceBinding
 	Values    []*Value
 	Imports   []*ProviderSet
+	// InjectorArgs is only filled in for wire.Build.
+	InjectorArgs *InjectorArgs
 
 	// providerMap maps from provided type to a *ProvidedType.
 	// It includes all of the imported types.
@@ -190,6 +196,24 @@ type Value struct {
 	info *types.Info
 }
 
+// InjectorArg describes a specific argument passed to an injector function.
+type InjectorArg struct {
+	// Args is the full set of arguments.
+	Args *InjectorArgs
+	// Index is the index into Args.Tuple for this argument.
+	Index int
+}
+
+// InjectorArgs describes the arguments passed to an injector function.
+type InjectorArgs struct {
+	// Name is the name of the injector function.
+	Name string
+	// Tuple represents the arguments.
+	Tuple *types.Tuple
+	// Pos is the source position of the injector function.
+	Pos token.Pos
+}
+
 // Load finds all the provider sets in the packages that match the given
 // patterns, as well as the provider sets' transitive dependencies. It
 // may return both errors and Info. The patterns are defined by the
@@ -252,11 +276,6 @@ func Load(ctx context.Context, wd string, env []string, patterns []string) (*Inf
 				if buildCall == nil {
 					continue
 				}
-				set, errs := oc.processNewSet(pkg.TypesInfo, pkg.PkgPath, buildCall, "")
-				if len(errs) > 0 {
-					ec.add(notePositionAll(fset.Position(fn.Pos()), errs)...)
-					continue
-				}
 				sig := pkg.TypesInfo.ObjectOf(fn.Name).Type().(*types.Signature)
 				ins, out, err := injectorFuncSignature(sig)
 				if err != nil {
@@ -267,6 +286,16 @@ func Load(ctx context.Context, wd string, env []string, patterns []string) (*Inf
 					}
 					continue
 				}
+				injectorArgs := &InjectorArgs{
+					Name:  fn.Name.Name,
+					Tuple: ins,
+					Pos:   fn.Pos(),
+				}
+				set, errs := oc.processNewSet(pkg.TypesInfo, pkg.PkgPath, buildCall, injectorArgs, "")
+				if len(errs) > 0 {
+					ec.add(notePositionAll(fset.Position(fn.Pos()), errs)...)
+					continue
+				}
 				_, errs = solve(fset, out.out, ins, set)
 				if len(errs) > 0 {
 					ec.add(mapErrors(errs, func(e error) error {
@@ -482,7 +511,7 @@ func (oc *objectCache) processExpr(info *types.Info, pkgPath string, expr ast.Ex
 		}
 		switch fnObj.Name() {
 		case "NewSet":
-			pset, errs := oc.processNewSet(info, pkgPath, call, varName)
+			pset, errs := oc.processNewSet(info, pkgPath, call, nil, varName)
 			return pset, notePositionAll(exprPos, errs)
 		case "Bind":
 			b, err := processBind(oc.fset, info, call)
@@ -516,11 +545,12 @@ func (oc *objectCache) processExpr(info *types.Info, pkgPath string, expr ast.Ex
 	return nil, []error{notePosition(exprPos, errors.New("unknown pattern"))}
 }
 
-func (oc *objectCache) processNewSet(info *types.Info, pkgPath string, call *ast.CallExpr, varName string) (*ProviderSet, []error) {
+func (oc *objectCache) processNewSet(info *types.Info, pkgPath string, call *ast.CallExpr, args *InjectorArgs, varName string) (*ProviderSet, []error) {
 	// Assumes that call.Fun is wire.NewSet or wire.Build.
 
 	pset := &ProviderSet{
 		Pos:          call.Pos(),
+		InjectorArgs: args,
 		PkgPath:      pkgPath,
 		VarName:      varName,
 	}
@@ -626,17 +656,12 @@ func processFuncProvider(fset *token.FileSet, fn *types.Func) (*Provider, []erro
 	return provider, nil
 }
 
-func injectorFuncSignature(sig *types.Signature) ([]types.Type, outputSignature, error) {
+func injectorFuncSignature(sig *types.Signature) (*types.Tuple, outputSignature, error) {
 	out, err := funcOutput(sig)
 	if err != nil {
 		return nil, outputSignature{}, err
 	}
-	params := sig.Params()
-	given := make([]types.Type, params.Len())
-	for i := 0; i < params.Len(); i++ {
-		given[i] = params.At(i).Type()
-	}
-	return given, out, nil
+	return sig.Params(), out, nil
 }
 
 type outputSignature struct {
@@ -893,49 +918,66 @@ func isProviderSetType(t types.Type) bool {
 	return obj.Pkg() != nil && isWireImport(obj.Pkg().Path()) && obj.Name() == "ProviderSet"
 }
 
-// ProvidedType is a pointer to a Provider or a Value. The zero value is
-// a nil pointer. It also holds the concrete type that the Provider or Value
-// provided.
+// ProvidedType represents a type provided from a source. The source
+// can be a *Provider (a provider function), a *Value (wire.Value), or an
+// *InjectorArgs (arguments to the injector function). The zero value has
+// none of the above, and returns true for IsNil.
 type ProvidedType struct {
+	// t is the provided concrete type.
 	t types.Type
 	p *Provider
 	v *Value
+	a *InjectorArg
 }
 
-// IsNil reports whether pv is the zero value.
-func (pv ProvidedType) IsNil() bool {
-	return pv.p == nil && pv.v == nil
+// IsNil reports whether pt is the zero value.
+func (pt ProvidedType) IsNil() bool {
+	return pt.p == nil && pt.v == nil && pt.a == nil
 }
 
 // ConcreteType returns the concrete type that was provided.
-func (pv ProvidedType) ConcreteType() types.Type {
-	return pv.t
+func (pt ProvidedType) ConcreteType() types.Type {
+	return pt.t
 }
 
-// IsProvider reports whether pv points to a Provider.
-func (pv ProvidedType) IsProvider() bool {
-	return pv.p != nil
+// IsProvider reports whether pt points to a Provider.
+func (pt ProvidedType) IsProvider() bool {
+	return pt.p != nil
 }
 
-// IsValue reports whether pv points to a Value.
-func (pv ProvidedType) IsValue() bool {
-	return pv.v != nil
+// IsValue reports whether pt points to a Value.
+func (pt ProvidedType) IsValue() bool {
+	return pt.v != nil
 }
 
-// Provider returns pv as a Provider pointer. It panics if pv points to a
-// Value.
-func (pv ProvidedType) Provider() *Provider {
-	if pv.v != nil {
-		panic("Value pointer converted to a Provider")
-	}
-	return pv.p
+// IsArg reports whether pt points to an injector argument.
+func (pt ProvidedType) IsArg() bool {
+	return pt.a != nil
 }
 
-// Value returns pv as a Value pointer. It panics if pv points to a
-// Provider.
-func (pv ProvidedType) Value() *Value {
-	if pv.p != nil {
-		panic("Provider pointer converted to a Value")
+// Provider returns pt as a Provider pointer. It panics if pt does not point
+// to a Provider.
+func (pt ProvidedType) Provider() *Provider {
+	if pt.p == nil {
+		panic("ProvidedType does not hold a Provider")
 	}
-	return pv.v
+	return pt.p
+}
+
+// Value returns pt as a Value pointer. It panics if pt does not point
+// to a Value.
+func (pt ProvidedType) Value() *Value {
+	if pt.v == nil {
+		panic("ProvidedType does not hold a Value")
+	}
+	return pt.v
+}
+
+// Arg returns pt as an *InjectorArg representing an injector argument. It
+// panics if pt does not point to an arg.
+func (pt ProvidedType) Arg() *InjectorArg {
+	if pt.a == nil {
+		panic("ProvidedType does not hold an Arg")
+	}
+	return pt.a
 }

internal/wire/testdata/BindInjectorArg/want/program_out.txt

@@ -0,0 +1 @@
+hello

internal/wire/testdata/BindInjectorArg/want/wire_errs.txt

@@ -1 +0,0 @@
-example.com/foo/wire.go:x:y: no binding for *example.com/foo.Foo

internal/wire/testdata/BindInjectorArg/want/wire_gen.go

@@ -0,0 +1,13 @@
+// Code generated by Wire. DO NOT EDIT.
+
+//go:generate wire
+//+build !wireinject
+
+package main
+
+// Injectors from wire.go:
+
+func inject(foo *Foo) *Bar {
+	bar := NewBar(foo)
+	return bar
+}

internal/wire/testdata/InjectInputConflict/want/wire_errs.txt

@@ -1 +1,6 @@
-example.com/foo/wire.go:x:y: inject injectBar: input of example.com/foo.Foo conflicts with provider provideFoo at example.com/foo/foo.go:x:y
+example.com/foo/wire.go:x:y: wire.Build has multiple bindings for example.com/foo.Foo
+current:
+<- provider "provideFoo" (example.com/foo/foo.go:x:y)
+<- provider set "Set" (example.com/foo/foo.go:x:y)
+previous:
+<- argument foo to injector function injectBar (example.com/foo/wire.go:x:y)

internal/wire/testdata/MultipleArgsSameType/want/wire_errs.txt

@@ -1 +1,5 @@
-example.com/foo/wire.go:x:y: inject inject: multiple inputs of the same type string
+example.com/foo/wire.go:x:y: wire.Build has multiple bindings for string
+current:
+<- argument b to injector function inject (example.com/foo/wire.go:x:y)
+previous:
+<- argument a to injector function inject (example.com/foo/wire.go:x:y)

internal/wire/testdata/UnexportedStruct/bar/bar.go

@@ -17,5 +17,3 @@ package bar
 var foo struct {
 	X int
 }
-
-

internal/wire/wire.go

@@ -132,12 +132,26 @@ func generateInjectors(g *gen, pkg *packages.Package) (injectorFiles []*ast.File
 				g.p("// Injectors from %s:\n\n", name)
 				injectorFiles = append(injectorFiles, f)
 			}
-			set, errs := oc.processNewSet(pkg.TypesInfo, pkg.PkgPath, buildCall, "")
+			sig := pkg.TypesInfo.ObjectOf(fn.Name).Type().(*types.Signature)
+			ins, _, err := injectorFuncSignature(sig)
+			if err != nil {
+				if w, ok := err.(*wireErr); ok {
+					ec.add(notePosition(w.position, fmt.Errorf("inject %s: %v", fn.Name.Name, w.error)))
+				} else {
+					ec.add(notePosition(g.pkg.Fset.Position(fn.Pos()), fmt.Errorf("inject %s: %v", fn.Name.Name, err)))
+				}
+				continue
+			}
+			injectorArgs := &InjectorArgs{
+				Name:  fn.Name.Name,
+				Tuple: ins,
+				Pos:   fn.Pos(),
+			}
+			set, errs := oc.processNewSet(pkg.TypesInfo, pkg.PkgPath, buildCall, injectorArgs, "")
 			if len(errs) > 0 {
 				ec.add(notePositionAll(g.pkg.Fset.Position(fn.Pos()), errs)...)
 				continue
 			}
-			sig := pkg.TypesInfo.ObjectOf(fn.Name).Type().(*types.Signature)
 			if errs := g.inject(fn.Pos(), fn.Name.Name, sig, set); len(errs) > 0 {
 				ec.add(errs...)
 				continue
@@ -249,11 +263,7 @@ func (g *gen) inject(pos token.Pos, name string, sig *types.Signature, set *Prov
 			fmt.Errorf("inject %s: %v", name, err))}
 	}
 	params := sig.Params()
-	given := make([]types.Type, params.Len())
-	for i := 0; i < params.Len(); i++ {
-		given[i] = params.At(i).Type()
-	}
-	calls, errs := solve(g.pkg.Fset, injectSig.out, given, set)
+	calls, errs := solve(g.pkg.Fset, injectSig.out, params, set)
 	if len(errs) > 0 {
 		return mapErrors(errs, func(e error) error {
 			if w, ok := e.(*wireErr); ok {