internal/pkg: optional shallow external cure

This saves time and is often more practical even for package maintainers.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pkg/ir.go

@@ -90,7 +90,7 @@ type IContext struct {
 	// returns and must not be exposed directly.
 	w io.Writer
 	// Optional [Artifact] to cureRes cache, replaces [IRKindIdent] with
-	// checksum values if non-nil.
+	// checksum values if non-nil. The pathname field may not be populated.
 	inputs map[Artifact]cureRes
 }
 
@@ -173,7 +173,7 @@ func (i *IContext) mustWrite(p []byte) {
 
 // WriteIdent writes the identifier of [Artifact] to the IR. The behaviour of
 // WriteIdent is not defined for an [Artifact] not part of the slice returned by
-// [Artifact.Dependencies].
+// [Artifact.Inputs].
 func (i *IContext) WriteIdent(a Artifact) {
 	buf := i.ic.getIdentBuf()
 	defer i.ic.putIdentBuf(buf)
@@ -235,7 +235,8 @@ func (ic *irCache) Encode(w io.Writer, a Artifact) (err error) {
 }
 
 // encode implements Encode but replaces identifiers with their cured checksums
-// for a non-nil ident. Caller must acquire Cache.identMu.
+// for a non-nil ident. The pathname field is unused. Caller must acquire
+// Cache.identMu.
 func (ic *irCache) encode(
 	w io.Writer,
 	a Artifact,
@@ -432,9 +433,9 @@ type (
 		// Common buffer for word-sized reads.
 		buf [wordSize]byte
 
-		// Dependencies sent before params, sorted by identifier. Resliced on
+		// Inputs sent before params, sorted by identifier. Resliced on
 		// each call to Next and checked to be depleted during Finalise.
-		deps []*extIdent
+		inputs []*extIdent
 
 		// Number of values already read, -1 denotes a finalised IRReader.
 		count int
@@ -518,7 +519,7 @@ const (
 	irMaxValues = 1 << 12
 
 	// irMaxDeps is the arbitrary maximum number of direct dependencies allowed
-	// to be returned by [Artifact.Dependencies] and subsequently decoded by
+	// to be returned by [Artifact.Inputs] and subsequently decoded by
 	// [IRDecoder].
 	irMaxDeps = 1 << 10
 )
@@ -603,17 +604,17 @@ func (ir *IRReader) mustReadHeader(k IRValueKind) {
 
 // putAll returns all dependency buffers to the underlying [Cache].
 func (ir *IRReader) putAll() {
-	for _, buf := range ir.deps {
+	for _, buf := range ir.inputs {
 		ir.d.c.putIdentBuf(buf)
 	}
-	ir.deps = nil
+	ir.inputs = nil
 }
 
 // DiscardAll discards all unstructured dependencies. This is useful to
 // implementations that encode dependencies as [IRKindIdent] which are read back
 // via ReadIdent.
 func (ir *IRReader) DiscardAll() {
-	if ir.deps == nil {
+	if ir.inputs == nil {
 		panic("attempting to discard dependencies twice")
 	}
 	ir.putAll()
@@ -625,13 +626,13 @@ var ErrDependencyDepleted = errors.New("reading past end of dependencies")
 
 // Next returns the next unstructured dependency.
 func (ir *IRReader) Next() Artifact {
-	if len(ir.deps) == 0 {
+	if len(ir.inputs) == 0 {
 		panic(ErrDependencyDepleted)
 	}
 
-	id := unique.Make(ID(ir.deps[0][wordSize:]))
-	ir.d.c.putIdentBuf(ir.deps[0])
-	ir.deps = ir.deps[1:]
+	id := unique.Make(ID(ir.inputs[0][wordSize:]))
+	ir.d.c.putIdentBuf(ir.inputs[0])
+	ir.inputs = ir.inputs[1:]
 
 	if a, ok := ir.d.ident[id]; !ok {
 		ir.putAll()
@@ -684,8 +685,8 @@ func (ir *IRReader) Finalise() (checksum unique.Handle[Checksum], ok bool) {
 	}
 	ir.r, ir.ibw = nil, nil
 
-	if len(ir.deps) != 0 {
-		panic(MissedDependencyError(len(ir.deps)))
+	if len(ir.inputs) != 0 {
+		panic(MissedDependencyError(len(ir.inputs)))
 	}
 
 	return
@@ -778,11 +779,11 @@ func (d *IRDecoder) decode() (a Artifact, err error) {
 		err = ErrIRDepend
 		return
 	}
-	ir.deps = make([]*extIdent, sz)
-	for i := range ir.deps {
-		ir.deps[i] = d.c.getIdentBuf()
+	ir.inputs = make([]*extIdent, sz)
+	for i := range ir.inputs {
+		ir.inputs[i] = d.c.getIdentBuf()
 	}
-	for _, buf := range ir.deps {
+	for _, buf := range ir.inputs {
 		ir.mustRead(buf[:])
 	}