[release-branch.go1.11] cmd/cgo: ignore unrecognized GCC warning group pragmas

CL 159859 causes build failure with old clang versions (3.4.1) on FreeBSD 10.3/10.4.

Update #29962

Reviewed-on: https://go-review.googlesource.com/c/160777
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
(cherry picked from commit 6f4dc1ccf9735013fdb7cd044bda29d19bebb906)

Change-Id: Ie78d552ea6494fe3c4059847b26c2a6e206f9515
Reviewed-on: https://go-review.googlesource.com/c/160780
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/cmd/cgo/out.go b/src/cmd/cgo/out.go
index bbed5d598fc2353d4ef0c4cf4b88634513ca4c13..1c36b80088c3a477637b66d7f54ac87f8f57a241 100644 (file)
--- a/src/cmd/cgo/out.go
+++ b/src/cmd/cgo/out.go
@@ -741,6 +741,8 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
        fmt.Fprintf(fgcc, "#include \"_cgo_export.h\"\n\n")
 
        // We use packed structs, but they are always aligned.
+       // The pragmas and address-of-packed-member are not recognized as warning groups in clang 3.4.1, so ignore unknown pragmas first.
+       fmt.Fprintf(fgcc, "#pragma GCC diagnostic ignored \"-Wunknown-pragmas\"\n")
        fmt.Fprintf(fgcc, "#pragma GCC diagnostic ignored \"-Wpragmas\"\n")
        fmt.Fprintf(fgcc, "#pragma GCC diagnostic ignored \"-Waddress-of-packed-member\"\n")
 
@@ -1345,6 +1347,9 @@ __cgo_size_assert(double, 8)
 extern char* _cgo_topofstack(void);
 
 /* We use packed structs, but they are always aligned.  */
+/* The pragmas and address-of-packed-member are not recognized as warning groups in clang 3.4.1, so ignore unknown pragmas first. */
+
+#pragma GCC diagnostic ignored "-Wunknown-pragmas"
 #pragma GCC diagnostic ignored "-Wpragmas"
 #pragma GCC diagnostic ignored "-Waddress-of-packed-member"