[release-branch.go1.15] cmd/compile: make go:notinheap error message friendlier for cgo

Update #40954

Change-Id: Ifaab7349631ccb12fc892882bbdf7f0ebf3d845f
Reviewed-on: https://go-review.googlesource.com/c/go/+/251158
Run-TryBot: Keith Randall <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Trust: Keith Randall <[email protected]>
Reviewed-on: https://go-review.googlesource.com/c/go/+/255338
Reviewed-by: Austin Clements <[email protected]>

Author: randall77

src/cmd/compile/internal/gc/escape.go

@@ -1030,7 +1030,7 @@ func (e *Escape) newLoc(n *Node, transient bool) *EscLocation {
 		Fatalf("e.curfn isn't set")
 	}
 	if n != nil && n.Type != nil && n.Type.NotInHeap() {
-		yyerrorl(n.Pos, "%v is go:notinheap; stack allocation disallowed", n.Type)
+		yyerrorl(n.Pos, "%v is incomplete (or unallocatable); stack allocation disallowed", n.Type)
 	}
 
 	n = canonicalNode(n)

src/cmd/compile/internal/gc/subr.go

@@ -696,14 +696,14 @@ func convertop(srcConstant bool, src, dst *types.Type, why *string) Op {
 	// (a) Disallow (*T) to (*U) where T is go:notinheap but U isn't.
 	if src.IsPtr() && dst.IsPtr() && dst.Elem().NotInHeap() && !src.Elem().NotInHeap() {
 		if why != nil {
-			*why = fmt.Sprintf(":\n\t%v is go:notinheap, but %v is not", dst.Elem(), src.Elem())
+			*why = fmt.Sprintf(":\n\t%v is incomplete (or unallocatable), but %v is not", dst.Elem(), src.Elem())
 		}
 		return OXXX
 	}
 	// (b) Disallow string to []T where T is go:notinheap.
 	if src.IsString() && dst.IsSlice() && dst.Elem().NotInHeap() && (dst.Elem().Etype == types.Bytetype.Etype || dst.Elem().Etype == types.Runetype.Etype) {
 		if why != nil {
-			*why = fmt.Sprintf(":\n\t%v is go:notinheap", dst.Elem())
+			*why = fmt.Sprintf(":\n\t%v is incomplete (or unallocatable)", dst.Elem())
 		}
 		return OXXX
 	}

src/cmd/compile/internal/gc/typecheck.go

@@ -471,10 +471,10 @@ func typecheck1(n *Node, top int) (res *Node) {
 			return n
 		}
 		if l.Type.NotInHeap() {
-			yyerror("go:notinheap map key not allowed")
+			yyerror("incomplete (or unallocatable) map key not allowed")
 		}
 		if r.Type.NotInHeap() {
-			yyerror("go:notinheap map value not allowed")
+			yyerror("incomplete (or unallocatable) map value not allowed")
 		}
 
 		setTypeNode(n, types.NewMap(l.Type, r.Type))
@@ -491,7 +491,7 @@ func typecheck1(n *Node, top int) (res *Node) {
 			return n
 		}
 		if l.Type.NotInHeap() {
-			yyerror("chan of go:notinheap type not allowed")
+			yyerror("chan of incomplete (or unallocatable) type not allowed")
 		}
 
 		setTypeNode(n, types.NewChan(l.Type, n.TChanDir()))

src/cmd/compile/internal/gc/walk.go

@@ -640,7 +640,7 @@ opswitch:
 			// x = append(...)
 			r := n.Right
 			if r.Type.Elem().NotInHeap() {
-				yyerror("%v is go:notinheap; heap allocation disallowed", r.Type.Elem())
+				yyerror("%v can't be allocated in Go; it is incomplete (or unallocatable)", r.Type.Elem())
 			}
 			switch {
 			case isAppendOfMake(r):
@@ -1152,7 +1152,7 @@ opswitch:
 
 	case ONEW:
 		if n.Type.Elem().NotInHeap() {
-			yyerror("%v is go:notinheap; heap allocation disallowed", n.Type.Elem())
+			yyerror("%v can't be allocated in Go; it is incomplete (or unallocatable)", n.Type.Elem())
 		}
 		if n.Esc == EscNone {
 			if n.Type.Elem().Width >= maxImplicitStackVarSize {
@@ -1323,7 +1323,7 @@ opswitch:
 		}
 		t := n.Type
 		if t.Elem().NotInHeap() {
-			yyerror("%v is go:notinheap; heap allocation disallowed", t.Elem())
+			yyerror("%v can't be allocated in Go; it is incomplete (or unallocatable)", t.Elem())
 		}
 		if n.Esc == EscNone {
 			if !isSmallMakeSlice(n) {
@@ -1400,7 +1400,7 @@ opswitch:
 
 		t := n.Type
 		if t.Elem().NotInHeap() {
-			yyerror("%v is go:notinheap; heap allocation disallowed", t.Elem())
+			yyerror("%v can't be allocated in Go; it is incomplete (or unallocatable)", t.Elem())
 		}
 
 		length := conv(n.Left, types.Types[TINT])

test/notinheap.go

@@ -23,11 +23,11 @@ type embed3 struct { // ERROR "must be go:notinheap"
 	x [1]nih
 }
 
-type embed4 map[nih]int // ERROR "go:notinheap map key not allowed"
+type embed4 map[nih]int // ERROR "incomplete \(or unallocatable\) map key not allowed"
 
-type embed5 map[int]nih // ERROR "go:notinheap map value not allowed"
+type embed5 map[int]nih // ERROR "incomplete \(or unallocatable\) map value not allowed"
 
-type emebd6 chan nih // ERROR "chan of go:notinheap type not allowed"
+type emebd6 chan nih // ERROR "chan of incomplete \(or unallocatable\) type not allowed"
 
 type okay1 *nih
 
@@ -64,8 +64,8 @@ var sink interface{}
 
 func i() {
 	sink = new(t1)                     // no error
-	sink = (*t2)(new(t1))              // ERROR "cannot convert(.|\n)*t2 is go:notinheap"
-	sink = (*t2)(new(struct{ x int })) // ERROR "cannot convert(.|\n)*t2 is go:notinheap"
-	sink = []t3("foo")                 // ERROR "cannot convert(.|\n)*t3 is go:notinheap"
-	sink = []t4("bar")                 // ERROR "cannot convert(.|\n)*t4 is go:notinheap"
+	sink = (*t2)(new(t1))              // ERROR "cannot convert(.|\n)*t2 is incomplete \(or unallocatable\)"
+	sink = (*t2)(new(struct{ x int })) // ERROR "cannot convert(.|\n)*t2 is incomplete \(or unallocatable\)"
+	sink = []t3("foo")                 // ERROR "cannot convert(.|\n)*t3 is incomplete \(or unallocatable\)"
+	sink = []t4("bar")                 // ERROR "cannot convert(.|\n)*t4 is incomplete \(or unallocatable\)"
 }

test/notinheap2.go

@@ -20,7 +20,7 @@ var x nih
 // Stack variables are not okay.
 
 func f() {
-	var y nih // ERROR "nih is go:notinheap; stack allocation disallowed"
+	var y nih // ERROR "nih is incomplete \(or unallocatable\); stack allocation disallowed"
 	x = y
 }
 
@@ -34,13 +34,13 @@ var w []nih
 var n int
 
 func g() {
-	y = new(nih)              // ERROR "heap allocation disallowed"
-	y2 = new(struct{ x nih }) // ERROR "heap allocation disallowed"
-	y3 = new([1]nih)          // ERROR "heap allocation disallowed"
-	z = make([]nih, 1)        // ERROR "heap allocation disallowed"
-	z = append(z, x)          // ERROR "heap allocation disallowed"
+	y = new(nih)              // ERROR "can't be allocated in Go"
+	y2 = new(struct{ x nih }) // ERROR "can't be allocated in Go"
+	y3 = new([1]nih)          // ERROR "can't be allocated in Go"
+	z = make([]nih, 1)        // ERROR "can't be allocated in Go"
+	z = append(z, x)          // ERROR "can't be allocated in Go"
 	// Test for special case of OMAKESLICECOPY
-	x := make([]nih, n) // ERROR "heap allocation disallowed"
+	x := make([]nih, n) // ERROR "can't be allocated in Go"
 	copy(x, z)
 	z = x
 }