cmd/cgo: annotate named return struct members in comments

If an exported function has named return variables, then show the names
as comments in the return struct we create in the header file.

Example here:

 https://groups.google.com/forum/#!topic/golang-nuts/r393ne4zIfY

Change-Id: I21fb4ca2673f6977bec35ccab0cef7d42b311f96
Reviewed-on: https://go-review.googlesource.com/13061
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/cmd/cgo/out.go b/src/cmd/cgo/out.go
index 4a371fe702a989d1ca1a22d07e1a0b38efc30797..aaa105d6fd1bc0b03cdd4230f9511448f1140902 100644 (file)
--- a/src/cmd/cgo/out.go
+++ b/src/cmd/cgo/out.go
@@ -693,7 +693,7 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
                }
                fntype := fn.Type
                forFieldList(fntype.Params,
-                       func(i int, atype ast.Expr) {
+                       func(i int, aname string, atype ast.Expr) {
                                t := p.cgoType(atype)
                                if off%t.Align != 0 {
                                        pad := t.Align - off%t.Align
@@ -711,7 +711,7 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
                        npad++
                }
                forFieldList(fntype.Results,
-                       func(i int, atype ast.Expr) {
+                       func(i int, aname string, atype ast.Expr) {
                                t := p.cgoType(atype)
                                if off%t.Align != 0 {
                                        pad := t.Align - off%t.Align
@@ -744,8 +744,12 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
                        fmt.Fprintf(fgcch, "\n/* Return type for %s */\n", exp.ExpName)
                        fmt.Fprintf(fgcch, "struct %s_return {\n", exp.ExpName)
                        forFieldList(fntype.Results,
-                               func(i int, atype ast.Expr) {
-                                       fmt.Fprintf(fgcch, "\t%s r%d;\n", p.cgoType(atype).C, i)
+                               func(i int, aname string, atype ast.Expr) {
+                                       fmt.Fprintf(fgcch, "\t%s r%d;", p.cgoType(atype).C, i)
+                                       if len(aname) > 0 {
+                                               fmt.Fprintf(fgcch, " /* %s */", aname)
+                                       }
+                                       fmt.Fprint(fgcch, "\n")
                                })
                        fmt.Fprintf(fgcch, "};\n")
                        gccResult = "struct " + exp.ExpName + "_return"
@@ -758,7 +762,7 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
                        s += " recv"
                }
                forFieldList(fntype.Params,
-                       func(i int, atype ast.Expr) {
+                       func(i int, aname string, atype ast.Expr) {
                                if i > 0 || fn.Recv != nil {
                                        s += ", "
                                }
@@ -783,7 +787,7 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
                        fmt.Fprintf(fgcc, "\ta.recv = recv;\n")
                }
                forFieldList(fntype.Params,
-                       func(i int, atype ast.Expr) {
+                       func(i int, aname string, atype ast.Expr) {
                                fmt.Fprintf(fgcc, "\ta.p%d = p%d;\n", i, i)
                        })
                fmt.Fprintf(fgcc, "\tcrosscall2(_cgoexp%s_%s, &a, %d);\n", cPrefix, exp.ExpName, off)
@@ -792,7 +796,7 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
                                fmt.Fprintf(fgcc, "\treturn a.r0;\n")
                        } else {
                                forFieldList(fntype.Results,
-                                       func(i int, atype ast.Expr) {
+                                       func(i int, aname string, atype ast.Expr) {
                                                fmt.Fprintf(fgcc, "\tr.r%d = a.r%d;\n", i, i)
                                        })
                                fmt.Fprintf(fgcc, "\treturn r;\n")
@@ -824,7 +828,7 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
                        fmt.Fprintf(fgo2, "func %s(recv ", goname)
                        conf.Fprint(fgo2, fset, fn.Recv.List[0].Type)
                        forFieldList(fntype.Params,
-                               func(i int, atype ast.Expr) {
+                               func(i int, aname string, atype ast.Expr) {
                                        fmt.Fprintf(fgo2, ", p%d ", i)
                                        conf.Fprint(fgo2, fset, atype)
                                })
@@ -832,7 +836,7 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
                        if gccResult != "void" {
                                fmt.Fprint(fgo2, " (")
                                forFieldList(fntype.Results,
-                                       func(i int, atype ast.Expr) {
+                                       func(i int, aname string, atype ast.Expr) {
                                                if i > 0 {
                                                        fmt.Fprint(fgo2, ", ")
                                                }
@@ -847,7 +851,7 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
                        }
                        fmt.Fprintf(fgo2, "recv.%s(", exp.Func.Name)
                        forFieldList(fntype.Params,
-                               func(i int, atype ast.Expr) {
+                               func(i int, aname string, atype ast.Expr) {
                                        if i > 0 {
                                                fmt.Fprint(fgo2, ", ")
                                        }
@@ -879,13 +883,13 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
                cdeclBuf := new(bytes.Buffer)
                resultCount := 0
                forFieldList(fntype.Results,
-                       func(i int, atype ast.Expr) { resultCount++ })
+                       func(i int, aname string, atype ast.Expr) { resultCount++ })
                switch resultCount {
                case 0:
                        fmt.Fprintf(cdeclBuf, "void")
                case 1:
                        forFieldList(fntype.Results,
-                               func(i int, atype ast.Expr) {
+                               func(i int, aname string, atype ast.Expr) {
                                        t := p.cgoType(atype)
                                        fmt.Fprintf(cdeclBuf, "%s", t.C)
                                })
@@ -894,9 +898,13 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
                        fmt.Fprintf(fgcch, "\n/* Return type for %s */\n", exp.ExpName)
                        fmt.Fprintf(fgcch, "struct %s_result {\n", exp.ExpName)
                        forFieldList(fntype.Results,
-                               func(i int, atype ast.Expr) {
+                               func(i int, aname string, atype ast.Expr) {
                                        t := p.cgoType(atype)
-                                       fmt.Fprintf(fgcch, "\t%s r%d;\n", t.C, i)
+                                       fmt.Fprintf(fgcch, "\t%s r%d;", t.C, i)
+                                       if len(aname) > 0 {
+                                               fmt.Fprintf(fgcch, " /* %s */", aname)
+                                       }
+                                       fmt.Fprint(fgcch, "\n")
                                })
                        fmt.Fprintf(fgcch, "};\n")
                        fmt.Fprintf(cdeclBuf, "struct %s_result", exp.ExpName)
@@ -911,7 +919,7 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
                }
                // Function parameters.
                forFieldList(fntype.Params,
-                       func(i int, atype ast.Expr) {
+                       func(i int, aname string, atype ast.Expr) {
                                if i > 0 || fn.Recv != nil {
                                        fmt.Fprintf(cdeclBuf, ", ")
                                }
@@ -956,7 +964,7 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
                        fmt.Fprint(fgcc, "recv")
                }
                forFieldList(fntype.Params,
-                       func(i int, atype ast.Expr) {
+                       func(i int, aname string, atype ast.Expr) {
                                if i > 0 || fn.Recv != nil {
                                        fmt.Fprintf(fgcc, ", ")
                                }
@@ -982,7 +990,7 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
                        printer.Fprint(fgo2, fset, fn.Recv.List[0].Type)
                }
                forFieldList(fntype.Params,
-                       func(i int, atype ast.Expr) {
+                       func(i int, aname string, atype ast.Expr) {
                                if i > 0 || fn.Recv != nil {
                                        fmt.Fprintf(fgo2, ", ")
                                }
@@ -993,7 +1001,7 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
                if resultCount > 0 {
                        fmt.Fprintf(fgo2, " (")
                        forFieldList(fntype.Results,
-                               func(i int, atype ast.Expr) {
+                               func(i int, aname string, atype ast.Expr) {
                                        if i > 0 {
                                                fmt.Fprint(fgo2, ", ")
                                        }
@@ -1013,7 +1021,7 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
                }
                fmt.Fprintf(fgo2, "%s(", exp.Func.Name)
                forFieldList(fntype.Params,
-                       func(i int, atype ast.Expr) {
+                       func(i int, aname string, atype ast.Expr) {
                                if i > 0 {
                                        fmt.Fprint(fgo2, ", ")
                                }
@@ -1071,19 +1079,19 @@ func (p *Package) gccgoSymbolPrefix() string {
 }
 
 // Call a function for each entry in an ast.FieldList, passing the
-// index into the list and the type.
-func forFieldList(fl *ast.FieldList, fn func(int, ast.Expr)) {
+// index into the list, the name if any, and the type.
+func forFieldList(fl *ast.FieldList, fn func(int, string, ast.Expr)) {
        if fl == nil {
                return
        }
        i := 0
        for _, r := range fl.List {
                if r.Names == nil {
-                       fn(i, r.Type)
+                       fn(i, "", r.Type)
                        i++
                } else {
-                       for range r.Names {
-                               fn(i, r.Type)
+                       for _, n := range r.Names {
+                               fn(i, n.Name, r.Type)
                                i++
                        }
                }