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cmd/cgo: for -godefs, promote first field of anonymous union

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Update #6677

When a struct contains an anonymous union, use the type and
name of the first field in the union.

This should make the glibc <sys/resource.h> file work; in that
file struct rusage has fields like

__extension__ union
{
        long int ru_maxrss;
        __syscall_slong_t __ru_maxrss_word;
};

in which the field that matters is ru_maxrss and
__ru_maxrss_word just exists to advance to the next field on
systems where the kernel uses long long fields but userspace
expects long fields.

LGTM=mikioh.mikioh
R=golang-codereviews, mikioh.mikioh
CC=golang-codereviews
https://golang.org/cl/106260044
This commit is contained in:
Ian Lance Taylor 2014-08-05 17:10:15 -07:00
parent f6f2f77142
commit f2f17c0ff2
4 changed files with 79 additions and 2 deletions
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23
src/cmd/cgo/gcc.go
View file

@ -1548,7 +1548,27 @@ func (c *typeConv) Struct(dt *dwarf.StructType, pos token.Pos) (expr *ast.Struct
fld = c.pad(fld, f.ByteOffset-off)
off = f.ByteOffset
}
t := c.Type(f.Type, pos)
name := f.Name
ft := f.Type
// In godefs or cdefs mode, if this field is a C11
// anonymous union then treat the first field in the
// union as the field in the struct. This handles
// cases like the glibc <sys/resource.h> file; see
// issue 6677.
if *godefs || *cdefs {
if st, ok := f.Type.(*dwarf.StructType); ok && name == "" && st.Kind == "union" && len(st.Field) > 0 && !used[st.Field[0].Name] {
name = st.Field[0].Name
ident[name] = name
ft = st.Field[0].Type
}
}
// TODO: Handle fields that are anonymous structs by
// promoting the fields of the inner struct.
t := c.Type(ft, pos)
tgo := t.Go
size := t.Size
talign := t.Align
@ -1577,7 +1597,6 @@ func (c *typeConv) Struct(dt *dwarf.StructType, pos token.Pos) (expr *ast.Struct
}
n := len(fld)
fld = fld[0 : n+1]
name := f.Name
if name == "" {
name = fmt.Sprintf("anon%d", anon)
anon++