internal/core/export: don't add empty temp struct

Fixes bug where a temporary struct was added even if the
underlying value itself was not a struct.

Fixes cue-lang#1284

Signed-off-by: Marcel van Lohuizen <[email protected]>

Change-Id: I29c615c4670594d00725dd54e13ca96b3b33e304
Signed-off-by: Marcel van Lohuizen <[email protected]>
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/527841
Unity-Result: CUEcueckoo <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>
Reviewed-by: Paul Jolly <[email protected]>

internal/core/export/expr.go

@@ -191,13 +191,6 @@ func (x *exporter) mergeValues(label adt.Feature, src *adt.Vertex, a []conjunct,
 				s.Elts = append(s.Elts, st.Elts...)
 				return s
 			}
-		case 2:
-			if len(e.attrs) > 0 {
-				break
-			}
-			// Simplify.
-			e.conjuncts = append(e.conjuncts, e.embed...)
-			return ast.NewBinExpr(token.AND, e.conjuncts...)
 		}
 	}
 
@@ -258,7 +251,13 @@ func (x *exporter) mergeValues(label adt.Feature, src *adt.Vertex, a []conjunct,
 	// return ast.NewCall(ast.NewIdent("close"), s)
 	// }
 
-	e.conjuncts = append(e.conjuncts, s)
+	switch {
+	case len(e.conjuncts) == 0:
+		return s
+
+	case len(e.structs) > 0, len(s.Elts) > 0:
+		e.conjuncts = append(e.conjuncts, s)
+	}
 
 	return ast.NewBinExpr(token.AND, e.conjuncts...)
 }

internal/core/export/testdata/issue1284.txtar

@@ -0,0 +1,105 @@
+-- in.cue --
+a0: {
+    l: ["a",...]
+    l: ["a","b",...]
+}
+a1: {
+    l: [...]
+    l: ["a",...]
+    l: ["a","b",...]
+}
+a2: {
+    l: [...]
+    l: ["a",...]
+    l: ["a","b",...]
+    l: {}
+}
+a3: {
+    l: [...]
+    l: ["a",...]
+    l: ["a","b",...]
+    l: { _ }
+}
+a4: {
+    l: [...]
+    l: ["a",...]
+    l: ["a","b",...]
+    l: { _, #foo: 1 }
+    l: { _, @decl(1) }
+}
+-- out/definition --
+a0: {
+	l: ["a", ...] & ["a", "b", ...]
+}
+a1: {
+	l: [...] & ["a", ...] & ["a", "b", ...]
+}
+a2: {
+	l: [...] & ["a", ...] & ["a", "b", ...] & {}
+}
+a3: {
+	l: [...] & ["a", ...] & ["a", "b", ...] & {
+		_
+	}
+}
+a4: {
+	l: [...] & ["a", ...] & ["a", "b", ...] & {
+		@decl(1)
+		_
+		#foo: 1
+	}
+}
+-- out/doc --
+[]
+[a0]
+[a0 l]
+[a0 l 0]
+[a0 l 1]
+[a1]
+[a1 l]
+[a1 l 0]
+[a1 l 1]
+[a2]
+[a2 l]
+[a2 l 0]
+[a2 l 1]
+[a3]
+[a3 l]
+[a3 l 0]
+[a3 l 1]
+[a4]
+[a4 l]
+[a4 l #foo]
+[a4 l 0]
+[a4 l 1]
+-- out/value --
+== Simplified
+_|_ // a2.l: conflicting values ["a","b",...] and {} (mismatched types list and struct)
+== Raw
+_|_ // a2.l: conflicting values ["a","b",...] and {} (mismatched types list and struct)
+== Final
+_|_ // a2.l: conflicting values ["a","b",...] and {} (mismatched types list and struct)
+== All
+{
+	a0: {
+		l: ["a", "b"]
+	}
+	a1: {
+		l: ["a", "b"]
+	}
+	a2: {
+		l: _|_ // a2.l: conflicting values ["a","b",...] and {} (mismatched types list and struct)
+	}
+	a3: {
+		l: ["a", "b"]
+	}
+	a4: {
+		l: {
+			@decl(1)
+			#foo: 1
+			["a", "b"]
+		}
+	}
+}
+== Eval
+_|_ // a2.l: conflicting values ["a","b",...] and {} (mismatched types list and struct)