cmd/compile: improve typechecking of OSLICEHEADER nodes

Create a new node for OSLICEHEADER nodes to ensure typechecks are applied.
Add nil checks for OSLICEHEADER type and pointer parameters
for better error messages when these are not set.
Improve formatting of OSLICEHEADER nodes in compiler error messages.

Change-Id: Idea8f41bb4beb636f0e1fc381ff8d79b1d44fbae
Reviewed-on: https://go-review.googlesource.com/c/146997
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

diff --git a/src/cmd/compile/internal/gc/fmt.go b/src/cmd/compile/internal/gc/fmt.go
index 0f4b6c9936b7035353f9b84eb5e29c666538a71c..16b81e6a88df62994036febdf7df3c29e3f51120 100644 (file)
--- a/src/cmd/compile/internal/gc/fmt.go
+++ b/src/cmd/compile/internal/gc/fmt.go
@@ -1114,6 +1114,7 @@ var opprec = []int{
        OSLICEARR:     8,
        OSLICE3:       8,
        OSLICE3ARR:    8,
+       OSLICEHEADER:  8,
        ODOTINTER:     8,
        ODOTMETH:      8,
        ODOTPTR:       8,
@@ -1393,6 +1394,12 @@ func (n *Node) exprfmt(s fmt.State, prec int, mode fmtMode) {
                }
                fmt.Fprint(s, "]")
 
+       case OSLICEHEADER:
+               if n.List.Len() != 2 {
+                       Fatalf("bad OSLICEHEADER list length %d", n.List.Len())
+               }
+               mode.Fprintf(s, "sliceheader{%v,%v,%v}", n.Left, n.List.First(), n.List.Second())
+
        case OCOPY, OCOMPLEX:
                mode.Fprintf(s, "%#v(%v, %v)", n.Op, n.Left, n.Right)
 

diff --git a/src/cmd/compile/internal/gc/typecheck.go b/src/cmd/compile/internal/gc/typecheck.go
index 8ec60cbbba763cfe25255b5c2ec3d89986c4b310..e6a8ed4bda149ae951ad8c61cf12c22a413e666e 100644 (file)
--- a/src/cmd/compile/internal/gc/typecheck.go
+++ b/src/cmd/compile/internal/gc/typecheck.go
@@ -1160,11 +1160,15 @@ func typecheck1(n *Node, top int) (res *Node) {
                ok |= Erv
 
                t := n.Type
+               if t == nil {
+                       Fatalf("no type specified for OSLICEHEADER")
+               }
+
                if !t.IsSlice() {
                        Fatalf("invalid type %v for OSLICEHEADER", n.Type)
                }
 
-               if !n.Left.Type.IsUnsafePtr() {
+               if n.Left == nil || n.Left.Type == nil || !n.Left.Type.IsUnsafePtr() {
                        Fatalf("need unsafe.Pointer for OSLICEHEADER")
                }
 

diff --git a/src/cmd/compile/internal/gc/walk.go b/src/cmd/compile/internal/gc/walk.go
index f459cb3decd37327fbce908b3c3f067ed2156d27..fa0dcab5ebdee52cada8967ab108cd75af35a9ec 100644 (file)
--- a/src/cmd/compile/internal/gc/walk.go
+++ b/src/cmd/compile/internal/gc/walk.go
@@ -1351,14 +1351,17 @@ opswitch:
                                argtype = types.Types[TINT]
                        }
 
+                       m := nod(OSLICEHEADER, nil, nil)
+                       m.Type = t
+
                        fn := syslook(fnname)
-                       n.Left = mkcall1(fn, types.Types[TUNSAFEPTR], init, typename(t.Elem()), conv(len, argtype), conv(cap, argtype))
-                       n.Left.SetNonNil(true)
-                       n.List.Set2(conv(len, types.Types[TINT]), conv(cap, types.Types[TINT]))
-                       n.Op = OSLICEHEADER
-                       n.Type = t
-                       n = typecheck(n, Erv)
-                       n = walkexpr(n, init)
+                       m.Left = mkcall1(fn, types.Types[TUNSAFEPTR], init, typename(t.Elem()), conv(len, argtype), conv(cap, argtype))
+                       m.Left.SetNonNil(true)
+                       m.List.Set2(conv(len, types.Types[TINT]), conv(cap, types.Types[TINT]))
+
+                       m = typecheck(m, Erv)
+                       m = walkexpr(m, init)
+                       n = m
                }
 
        case ORUNESTR: