cmd/dist: bootstrap with gccgo fails

[stevenpackardblp]

What version of Go are you using (go version)?

Compiling 1.16.4 release source code using GCC 9.3 gccgo.

Does this issue reproduce with the latest release?

Yes.

What operating system and processor architecture are you using (go env)?

linux amd64

What did you do?

Attempting to build the 1.16.4 release using GCC 9.3 gccgo fails with:

GOOS=linux GOARCH=amd64 \
GOROOT=/tmp/go-1.16 \
GOROOT_FINAL=/opt/go-1.16 \
GOROOT_BOOTSTRAP=/opt/go \
GCCGO=gccgo \
./make.bash
Building Go cmd/dist using /opt/go. (go1.12.2 gccgo (9.3.0-2+b20210507T23473637) 9.3.0 linux/amd64)
Building Go toolchain1 using /opt/go.
# bootstrap/cmd/compile/internal/ssa
cmd/compile/internal/ssa/flags_amd64_test.s:11:10: fatal error: textflag.h: No such file or directory
   11 | #include "textflag.h"
      |          ^~~~~~~~~~~~
compilation terminated.

What did you expect to see?

Successful build

What did you see instead?

Failed build

This is the same regression as #40855 and #30771. This worked in 1.16.3, and has regressed in 1.16.4.

[apaprocki]

It appears that #40875 was entered to help detect/prevent this regression.

[cherrymui]

This is weird. I don't think there is anything changed related to this between 1.16.3 and 1.16.4. Could you double check you're building Go 1.16.4? Maybe try ./clean.bash; ./make.bash -v=3 and paste the output? Thanks.

[stevenpackardblp]

Well, this is embarrassing. I apparently copied the 1.15.12 URL and imported it as the 1.16.4 source into our system. Once I imported the correct source, everything worked as expected, so this is totally on me. Please do consider working on #40875, though!