cmd/cue: remove support for CUE_DEBUG_SORT_ARCS

This fairly old debugging flag worked on the old evaluator but never
worked on the new evaluator; we instead focused on a new field ordering
available for both versions via CUE_EXPERIMENT=toposort, which should
be enabled by default very soon, as well as a lexicographical ordering
available for now under CUE_DEBUG=sortfields.

Given that CUE_DEBUG_SORT_ARCS was never meant for end users nor
properly documented, that it never worked for evalv3, and that we now
have the two new field ordering mechanisms which work on both evaluator
versions, it's time to delete this code for v0.12.0-alpha.1.

Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: Ic02403693c871608929b65d4b019432e8a81c849
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1205985
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Reviewed-by: Matthew Sackman <matthew@cue.works>

cmd/cue/cmd/common.go

@@ -19,7 +19,6 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
-	"strconv"
 	"strings"
 
 	"github.com/spf13/pflag"
@@ -33,7 +32,6 @@ import (
 	"cuelang.org/go/cue/parser"
 	"cuelang.org/go/cue/token"
 	"cuelang.org/go/internal"
-	"cuelang.org/go/internal/core/adt"
 	"cuelang.org/go/internal/encoding"
 	"cuelang.org/go/internal/filetypes"
 )
@@ -504,8 +502,6 @@ func parseArgs(cmd *Command, args []string, cfg *config) (p *buildPlan, err erro
 		return nil, err
 	}
 
-	adt.DebugSort, _ = strconv.Atoi(os.Getenv("CUE_DEBUG_SORT_ARCS"))
-
 	builds := loadFromArgs(args, cfg.loadCfg)
 	if builds == nil {
 		return nil, errors.Newf(token.NoPos, "invalid args")

internal/core/adt/context.go

@@ -19,7 +19,6 @@ import (
 	"log"
 	"reflect"
 	"regexp"
-	"sort"
 	"strings"
 
 	"github.com/cockroachdb/apd/v3"
@@ -33,47 +32,6 @@ import (
 	"cuelang.org/go/internal/cuedebug"
 )
 
-// DebugSort specifies that arcs be sorted consistently between implementations.
-//
-//	0: default
-//	1: sort by Feature: this should be consistent between implementations where
-//		   there is no change in the compiler and indexing code.
-//	2: alphabetical
-//
-// TODO: move to DebugFlags
-var DebugSort int
-
-func DebugSortArcs(c *OpContext, n *Vertex) {
-	if n.IsList() {
-		return
-	}
-	switch a := n.Arcs; DebugSort {
-	case 1:
-		sort.SliceStable(a, func(i, j int) bool {
-			return a[i].Label < a[j].Label
-		})
-	case 2:
-		sort.SliceStable(a, func(i, j int) bool {
-			return a[i].Label.SelectorString(c.Runtime) <
-				a[j].Label.SelectorString(c.Runtime)
-		})
-	}
-}
-
-func DebugSortFields(c *OpContext, a []Feature) {
-	switch DebugSort {
-	case 1:
-		sort.SliceStable(a, func(i, j int) bool {
-			return a[i] < a[j]
-		})
-	case 2:
-		sort.SliceStable(a, func(i, j int) bool {
-			return a[i].SelectorString(c.Runtime) <
-				a[j].SelectorString(c.Runtime)
-		})
-	}
-}
-
 // Assert panics if the condition is false. Assert can be used to check for
 // conditions that are considers to break an internal variant or unexpected
 // condition, but that nonetheless probably will be handled correctly down the

internal/core/adt/eval.go

@@ -809,10 +809,6 @@ func (n *nodeContext) checkClosed(state vertexStatus) bool {
 func (n *nodeContext) completeArcs(state vertexStatus) {
 	unreachableForDev(n.ctx)
 
-	if DebugSort > 0 {
-		DebugSortArcs(n.ctx, n.node)
-	}
-
 	if n.node.hasAllConjuncts || n.node.Parent == nil {
 		n.node.setParentDone()
 	}

internal/core/adt/unify.go

@@ -250,10 +250,6 @@ func (v *Vertex) unify(c *OpContext, needs condition, mode runMode) bool {
 		// done
 
 	case needs&subFieldsProcessed != 0:
-		if DebugSort > 0 {
-			DebugSortArcs(n.ctx, n.node)
-		}
-
 		switch {
 		case assertStructuralCycleV3(n):
 		// TODO: consider bailing on error if n.errs != nil.

internal/core/export/expr.go

@@ -189,20 +189,16 @@ func (x *exporter) mergeValues(label adt.Feature, src *adt.Vertex, a []conjunct,
 		return -cmp.Compare(f1, f2)
 	})
 
-	if adt.DebugSort == 0 {
-		m := sortArcs(extractFeatures(e.structs))
-		slices.SortStableFunc(fields, func(f1, f2 adt.Feature) int {
-			if m[f2] == 0 {
-				if m[f1] == 0 {
-					return +1
-				}
-				return -1
+	m := sortArcs(extractFeatures(e.structs))
+	slices.SortStableFunc(fields, func(f1, f2 adt.Feature) int {
+		if m[f2] == 0 {
+			if m[f1] == 0 {
+				return +1
 			}
-			return -cmp.Compare(m[f1], m[f2])
-		})
-	} else {
-		adt.DebugSortFields(e.ctx, fields)
-	}
+			return -1
+		}
+		return -cmp.Compare(m[f1], m[f2])
+	})
 
 	if len(e.fields) == 0 && !e.hasEllipsis {
 		switch len(e.embed) + len(e.conjuncts) {

internal/core/export/toposort.go

@@ -32,11 +32,11 @@ func VertexFeatures(c *adt.OpContext, v *adt.Vertex) []adt.Feature {
 	if c.TopoSort {
 		return toposort.VertexFeatures(c, v)
 	} else {
-		return vertexFeatures(c, v)
+		return vertexFeatures(v)
 	}
 }
 
-func vertexFeatures(c *adt.OpContext, v *adt.Vertex) []adt.Feature {
+func vertexFeatures(v *adt.Vertex) []adt.Feature {
 	sets := extractFeatures(v.Structs)
 	m := sortArcs(sets) // TODO: use for convenience.
 
@@ -54,11 +54,7 @@ func vertexFeatures(c *adt.OpContext, v *adt.Vertex) []adt.Feature {
 		sets = append(sets, a)
 	}
 
-	a = sortedArcs(sets)
-	if adt.DebugSort > 0 {
-		adt.DebugSortFields(c, a)
-	}
-	return a
+	return sortedArcs(sets)
 }
 
 func extractFeatures(in []*adt.StructInfo) (a [][]adt.Feature) {

tools/flow/flow.go

@@ -90,6 +90,7 @@ var (
 	// TODO: ErrUpdate: update and run a dependency, but don't complete a
 	// dependency as more results may come. This is useful in server mode.
 
+	// TODO: move CUE_DEBUG_TOOLS_FLOW=1 to e.g. CUE_DEBUG=toolsflow
 	debug = os.Getenv("CUE_DEBUG_TOOLS_FLOW") != ""
 )