internal/core/export: fix dereferencing bug

In a previous fix we posponed the dereferencing of
a value, because we needed the non-dereferenced value
of the ArcType.

As it turns out, we also need the non-dereferenced value
for the docs and attributes. This change fixes that.

Note that the test has some modifications for a debug
testing. We leave this in for convenience down the line.
We leave the snippet itself to get an idea of the reducer
that was used to fix the code.

Issue #2884

Signed-off-by: Marcel van Lohuizen <mpvl@gmail.com>
Change-Id: I59c97bfdb53918cd83b88be23a3a4bc5391fdb6f
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1194651
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>

internal/core/export/testdata/main/attrs.txtar

@@ -331,7 +331,7 @@ dynamicSimple: {
 	} @field(2) @field(1) @field(4) @field(3) @field(5)
 	doNotPropagate: {
 		#A: {} @attr1()
-		a: {} @attr1()
+		a: {}
 
 		// Do not accumulated field attributes in embedding.
 		#B: {} @attr1()
@@ -399,7 +399,7 @@ dynamicSimple: {
 	} @field(2) @field(1) @field(4) @field(3) @field(5)
 	doNotPropagate: {
 		#A: {} @attr1()
-		a: {} @attr1()
+		a: {}
 		#B: {} @attr1()
 		b: {}
 	}
@@ -456,35 +456,10 @@ dynamicSimple: {
 diff old new
 --- old
 +++ new
-@@ -125,44 +125,45 @@
- 	} @field(2) @field(1) @field(4) @field(3) @field(5)
- 	doNotPropagate: {
- 		#A: {} @attr1()
--		a: {}
--
--		// Do not accumulated field attributes in embedding.
--		#B: {} @attr1()
--		b: {}
--	}
--	embedScalarField: {
--		a: 2 @attr1() @attr2()
--	}
--	embedScalarDecl: {
--		b0: {
--			2, @attr1()
--		}
--		b1: {
--			2, @attr1()
--		}
--		b2: {
--			2, @attr2(), @attr1()
--		}
--	}
--	dontMergeForDef: {
--		a: {
--			@decl1()
--		}
--		b: {
+@@ -150,19 +150,20 @@
+ 			@decl1()
+ 		}
+ 		b: {
 -			@decl1(), @decl2()
 -			x: 1
 -		}
@@ -498,31 +473,6 @@ diff old new
 -	comprehensions: {
 -		@step(0)
 -		@step(2c)
-+		a: {} @attr1()
-+
-+		// Do not accumulated field attributes in embedding.
-+		#B: {} @attr1()
-+		b: {}
-+	}
-+	embedScalarField: {
-+		a: 2 @attr1() @attr2()
-+	}
-+	embedScalarDecl: {
-+		b0: {
-+			2, @attr1()
-+		}
-+		b1: {
-+			2, @attr1()
-+		}
-+		b2: {
-+			2, @attr2(), @attr1()
-+		}
-+	}
-+	dontMergeForDef: {
-+		a: {
-+			@decl1()
-+		}
-+		b: {
 +			@decl2(), @decl1()
 +			x: 1
 +		}
@@ -540,33 +490,10 @@ diff old new
  		c1: {} @step(1)
  		c2: {
  			@step(2a)
-@@ -192,42 +193,43 @@
- 	} @field(2) @field(1) @field(4) @field(3) @field(5)
- 	doNotPropagate: {
- 		#A: {} @attr1()
--		a: {}
--		#B: {} @attr1()
--		b: {}
--	}
--	embedScalarField: {
--		a: 2 @attr1() @attr2()
--	}
--	embedScalarDecl: {
--		b0: {
--			2, @attr1()
--		}
--		b1: {
--			2, @attr1()
--		}
--		b2: {
--			2, @attr2(), @attr1()
--		}
--	}
--	dontMergeForDef: {
--		a: {
--			@decl1()
--		}
--		b: {
+@@ -215,19 +216,20 @@
+ 			@decl1()
+ 		}
+ 		b: {
 -			@decl1(), @decl2()
 -			x: 1
 -		}
@@ -580,29 +507,6 @@ diff old new
 -	comprehensions: {
 -		@step(0)
 -		@step(2c)
-+		a: {} @attr1()
-+		#B: {} @attr1()
-+		b: {}
-+	}
-+	embedScalarField: {
-+		a: 2 @attr1() @attr2()
-+	}
-+	embedScalarDecl: {
-+		b0: {
-+			2, @attr1()
-+		}
-+		b1: {
-+			2, @attr1()
-+		}
-+		b2: {
-+			2, @attr2(), @attr1()
-+		}
-+	}
-+	dontMergeForDef: {
-+		a: {
-+			@decl1()
-+		}
-+		b: {
 +			@decl2(), @decl1()
 +			x: 1
 +		}
@@ -621,9 +525,9 @@ diff old new
  		c2: {
  			@step(2a)
 -- diff/value/todo/p1 --
-== Eval.doNotPropagate
-.a: missing attribute.
-#B: missing comment
+comprehension: @step(4c) added in comprehensions
+-- diff/value/todo/p3 --
+Reordering of attributes.
 -- out/value --
 == Simplified
 {

internal/core/export/testdata/main/def.txtar

@@ -38,98 +38,6 @@ g: #d
 
 [g e]
 [g f]
--- out/value-v3 --
-== Simplified
-{
-	a: *2 | int
-	c: {}
-	g: {
-		e!: =~"a"
-	}
-}
-== Raw
-{
-	a:  *2 | int
-	b?: 4 | 5
-	c: {}
-	#d: {
-		e!: =~"a"
-		f?: 1
-	}
-	g: {
-		e!: =~"a"
-		f?: 1
-	}
-}
-== Final
-{
-	a: 2
-	c: {}
-	g: {
-		e!: =~"a"
-	}
-}
-== All
-{
-	a:  *2 | int
-	b?: 4 | 5
-	c: {}
-	#d: {
-		e!: =~"a"
-		f?: 1
-	}
-	g: {
-		e!: =~"a"
-		f?: 1
-	}
-}
-== Eval
-{
-	a:  2
-	b?: 4 | 5
-	c: {}
-	#d: {
-		e!: =~"a"
-		f?: 1
-	}
-	g: {
-		e!: =~"a"
-		f?: 1
-	}
-}
--- diff/-out/value-v3<==>+out/value --
-diff old new
---- old
-+++ new
-@@ -2,8 +2,6 @@
- {
- 	a: *2 | int
- 	c: {}
--
--	// Issue #2305
- 	g: {
- 		e!: =~"a"
- 	}
-@@ -17,8 +15,6 @@
- 		e!: =~"a"
- 		f?: 1
- 	}
--
--	// Issue #2305
- 	g: {
- 		e!: =~"a"
- 		f?: 1
-@@ -41,8 +37,6 @@
- 		e!: =~"a"
- 		f?: 1
- 	}
--
--	// Issue #2305
- 	g: {
- 		e!: =~"a"
- 		f?: 1
--- diff/value/todo/p1 --
-Missing comments.
 -- out/value --
 == Simplified
 {

internal/core/export/value.go

@@ -446,8 +446,7 @@ func (e *exporter) structComposite(v *adt.Vertex, attrs []*ast.Attribute) ast.Ex
 
 		internal.SetConstraint(f, arc.ArcType.Token())
 
-		arc = arc.DerefValue()
-		f.Value = e.vertex(arc)
+		f.Value = e.vertex(arc.DerefValue())
 
 		if label.IsDef() {
 			e.inDefinition--

internal/core/export/value_test.go

@@ -37,11 +37,21 @@ var exclude = map[string]string{
 }
 
 func TestValue(t *testing.T) {
+	const debugValue = `
+-- in.cue --
+// Issue #2305
+g: #d
+#d: 1
+`
+
 	test := cuetxtar.TxTarTest{
 		Root:   "./testdata/main",
 		Name:   "value",
 		Skip:   exclude,
 		Matrix: cuetdtest.SmallMatrix,
+
+		// Uncomment to debug an isolated test case.
+		// DebugArchive: debugValue,
 	}
 
 	test.Run(t, func(t *cuetxtar.Test) {