From 622a1ffd7236529d9774498742810ce1102b009f Mon Sep 17 00:00:00 2001
From: Dmitry Vyukov <dvyukov@google.com>
Date: Mon, 4 Sep 2017 19:53:01 +0200
Subject: pkg/compiler: prohibit bitfields of size 0

They don't work the way C bitfields work.
So this will lead to confusion at least.
---
 pkg/compiler/testdata/errors.txt |  2 +-
 pkg/compiler/types.go            | 17 +++++++++++++----
 2 files changed, 14 insertions(+), 5 deletions(-)

(limited to 'pkg')

diff --git a/pkg/compiler/testdata/errors.txt b/pkg/compiler/testdata/errors.txt
index 512d615c8..c339dcb80 100644
--- a/pkg/compiler/testdata/errors.txt
+++ b/pkg/compiler/testdata/errors.txt
@@ -128,7 +128,7 @@ resource inout[int32]		### resource uses reserved name inout
 bar()
 
 s3 {
-	f1	int8:0
+	f1	int8:0		### bitfields of size 0 are not supported
 	f2	int8:1
 	f3	int8:7
 	f4	int8:8
diff --git a/pkg/compiler/types.go b/pkg/compiler/types.go
index 035a47165..29ef4dbf5 100644
--- a/pkg/compiler/types.go
+++ b/pkg/compiler/types.go
@@ -539,10 +539,19 @@ var typeArgBase = namedArg{
 		Names:      []string{"int8", "int16", "int32", "int64", "int16be", "int32be", "int64be", "intptr"},
 		AllowColon: true,
 		Check: func(comp *compiler, t *ast.Type) {
-			size, _ := comp.parseIntType(t.Ident)
-			if t.Value2 > size*8 {
-				comp.error(t.Pos2, "bitfield of size %v is too large for base type of size %v",
-					t.Value2, size*8)
+			if t.HasColon {
+				if t.Value2 == 0 {
+					// This was not supported historically
+					// and does not work the way C bitfields of size 0 work.
+					// We could allow this, but then we need to make
+					// this work the way C bitfields work.
+					comp.error(t.Pos2, "bitfields of size 0 are not supported")
+				}
+				size, _ := comp.parseIntType(t.Ident)
+				if t.Value2 > size*8 {
+					comp.error(t.Pos2, "bitfield of size %v is too large for base type of size %v",
+						t.Value2, size*8)
+				}
 			}
 		},
 	},
-- 
cgit mrf-deployment