all: don't use XXX strings unnecessarily

None of these were "XXX" comments in the sense that the code
cannot be in master, as described in #1959.
Use more realistic examples, other characters like NNN,
or Foo... rather than FooXXX when we mean any object with that prefix.

For #1959.

Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: Iece6ccbed29223ed44911f8fd1ecc622a6d443fc
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1193723
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Reviewed-by: Paul Jolly <paul@myitcv.io>

CONTRIBUTING.md

@@ -800,7 +800,7 @@ If you see something like...
 remote: Processing changes: refs: 1, done
 remote:
 remote: ERROR:  In commit ab13517fa29487dcf8b0d48916c51639426c5ee9
-remote: ERROR:  author email address XXXXXXXXXXXXXXXXXXX
+remote: ERROR:  author email address your.email@domain.com
 remote: ERROR:  does not match your user account.
 ```
 

cue/ast/astutil/sanitize.go

@@ -317,7 +317,7 @@ func (z *sanitizer) handleIdent(s *scope, n *ast.Ident) bool {
 }
 
 // uniqueName returns a new name globally unique name of the form
-// base_XX ... base_XXXXXXXXXXXXXX or _base or the same pattern with a '_'
+// base_NN ... base_NNNNNNNNNNNNNN or _base or the same pattern with a '_'
 // prefix if hidden is true.
 //
 // It prefers short extensions over large ones, while ensuring the likelihood of

cue/format/format_test.go

@@ -281,7 +281,7 @@ func TestNodes(t *testing.T) {
 
 }
 
-// Verify that the printer doesn't crash if the AST contains BadXXX nodes.
+// Verify that the printer doesn't crash if the AST contains Bad... nodes.
 func TestBadNodes(t *testing.T) {
 	const src = "package p\n("
 	const res = "package p\n\n(_|_)\n"

cue/parser/parser.go

@@ -52,11 +52,11 @@ type parser struct {
 	lit string      // token literal
 
 	// Error recovery
-	// (used to limit the number of calls to syncXXX functions
+	// (used to limit the number of calls to sync... functions
 	// w/o making scanning progress - avoids potential endless
 	// loops across multiple parser functions during error recovery)
 	syncPos token.Pos // last synchronization position
-	syncCnt int       // number of calls to syncXXX without progress
+	syncCnt int       // number of calls to sync... functions without progress
 
 	// Non-syntactic parser control
 	exprLev int // < 0: in control clause, >= 0: in expression

internal/core/adt/states.go

@@ -126,7 +126,7 @@ const (
 	// This is a signal condition that is reached when:
 	//    - a node is set to a concrete scalar value
 	//    - a node is set to an error
-	//    - or if XXXstate is reached.
+	//    - or if ...state is reached.
 	//
 	// TODO: rename to something better?
 	scalarKnown

internal/core/export/export.go

@@ -636,7 +636,7 @@ func (e *exporter) makeFeature(s string) (f adt.Feature, ok bool) {
 
 // uniqueFeature returns a name for an identifier that uniquely identifies
 // the given expression. If the preferred name is already taken, a new globally
-// unique name of the form base_X ... base_XXXXXXXXXXXXXX is generated.
+// unique name of the form base_N ... base_NNNNNNNNNNNNNN is generated.
 //
 // It prefers short extensions over large ones, while ensuring the likelihood of
 // fast termination is high. There are at least two digits to make it visually