[THRIFT-2793] Go compiler produces uncompilable code

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.9.2
• Fix Version/s: 0.9.2
• Component/s: Go - Compiler

Environment

OSX 10.10

• Patch Info: Patch Available
• Assignee: Jens Geyer
• Reporter: Frank Schroeder
• Created: 28/Oct/14 20:25
• Updated: 02/Feb/15 11:54
• Resolved: 05/Nov/14 08:26

Description

The Thrift Go compiler produces wrong code for the following code:

struct A { 1: list<B> b }
struct B { 1: i64 id }

The abbreviated reader method creates a []B instead of a []*B but still tries to add a &B{}.

 func (p *A) ReadField1(iprot thrift.TProtocol) error {
     ...
     tSlice := make([]B, 0, size)
     ...
     for i := 0; i < size; i++ {
         _elem0 := &B{}
         ...
         p.B = append(p.B, _elem0)
     }
     ...
 }

The Go compiler message is:

$ go version
go version go1.3.3 darwin/amd64
$ go build
./ttypes.go:74: cannot use _elem0 (type *B) as type B in append

Moving struct B above struct A produces correct code:

struct B { 1: i64 id }
struct A { 1: list<B> b }

The abbreviated reader method:

 func (p *A) ReadField1(iprot thrift.TProtocol) error {
     ...
     tSlice := make([]*B, 0, size)
     ...
     for i := 0; i < size; i++ {
         _elem0 := &B{}
         ...
         p.B = append(p.B, _elem0)
     }
     ...
 }

This problem does not occurr with enums since they are aliases for int64. So both versions generate correct code:

struct A { 1: list<B> b }
enum B { X }

and

enum B { X }
struct A { 1: list<B> b }

Tested with version 902b7af4c84b8f716668d4d4f10612c16109c09a from https://git-wip-us.apache.org/repos/asf/thrift.git.
I've built the thrift compiler with the following flags:

PATH=/opt/boxen/homebrew/Cellar/bison27/2.7.1/bin:$PATH ./configure \
    --without-cpp \
    --without-qt4 \
    --without-c_glib \
    --without-csharp \
    --without-java \
    --without-erlang \
    --without-nodejs \
    --without-lua \
    --without-python \
    --without-perl \
    --without-php \
    --without-php_extension \
    --without-ruby \
    --without-haskell \
    --with-go

and generate the thrift stubs as follows:

../compiler/cpp/thrift --gen go -out . model.thrift

I'll try to dig a bit through the source of the generator to see whether I can produce a patch.

Issue Links

• blocks: THRIFT-2796 Testcase for THRIFT-2793
• breaks: THRIFT-2955 Using list of typedefs does not compile on Go