cmd/compile,cmd/dist,cmd/go: compute -+ flag from package path

As we did for the asm -compiling-runtime flag, this CL modifies the
compiler to compute the -+ (compiling runtime) flag from the package
path. Unlike for asm, some tests use -+ explicitly to opt in to
runtime restrictions, so we leave the flag, but it's no longer passed
by any build tools.

This lets us eliminate cmd/go's list of "runtime packages" in favor of
the unified objabi.LookupPkgSpecial. It also fixes an inconsistency
with dist, which only passed -+ when compiling "runtime" itself.

One consequence of this is that the compiler now ignores the -N flag
when compiling runtime packages. Previously, cmd/go would strip -N
when passing -+ and the compiler would fatal if it got both -N and -+,
so the overall effect was that the compiler never saw -N when
compiling a runtime package. Now we simply move that logic to disable
-N down into the compiler.

Change-Id: I4876047a1563210ed122a31b72d62798762cbcf5
Reviewed-on: https://go-review.googlesource.com/c/go/+/521699
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

1 files changed, 0 insertions, 3 deletions

diff --git a/src/cmd/dist/build.go b/src/cmd/dist/build.go
index 031a8d9013..193db6f52d 100644
--- a/src/cmd/dist/build.go
+++ b/src/cmd/dist/build.go
@@ -946,9 +946,6 @@ func runInstall(pkg string, ch chan struct{}) {
 	if gogcflags != "" {
 		compile = append(compile, strings.Fields(gogcflags)...)
 	}
-	if pkg == "runtime" {
-		compile = append(compile, "-+")
-	}
 	if len(sfiles) > 0 {
 		compile = append(compile, "-asmhdr", goasmh)
 	}