cmd: support space and quotes in CC and CXX

The CC and CXX environment variables now support spaces and quotes
(both double and single). This fixes two issues: first, if CC is a
single path that contains spaces (like 'c:\Program
Files\gcc\bin\gcc.exe'), that should now work if the space is quoted
or escaped (#41400). Second, if CC or CXX has multiple arguments (like
'gcc -O2'), they are now split correctly, and the arguments are passed
before other arguments when invoking the C compiler. Previously,
strings.Fields was used to split arguments, and the arguments were
placed later in the command line. (#43078).

Fixes golang/go#41400
Fixes golang/go#43078

NOTE: This change also includes a fix (CL 341929) for a test that was
broken by the original CL. Commit message for the fix is below.

[dev.cmdgo] cmd/link: fix TestBuildForTvOS

This test was broken in CL 334732 on darwin.

The test invokes 'go build' with a CC containing the arguments
-framework CoreFoundation. Previously, the go command split CC on
whitespace, and inserted the arguments after the command line when
running CC directly. Those arguments weren't passed to cgo though,
so cgo ran CC without -framework CoreFoundation (or any of the other
flags).

In CL 334732, we pass CC through to cgo, and cgo splits arguments
using str.SplitQuotedFields. So -framework CoreFoundation actually
gets passed to the C compiler. It appears that -framework flags are
only meant to be used in linking operations, so when cgo invokes clang
with -E (run preprocessor only), clang emits an error that -framework
is unused.

This change fixes the test by moving -framework CoreFoundation out of
CC and into CGO_LDFLAGS.

Change-Id: I2d5d89ddb19c94adef65982a8137b01f037d5c11
Reviewed-on: https://go-review.googlesource.com/c/go/+/334732
Trust: Jay Conrod <jayconrod@google.com>
Trust: Michael Matloob <matloob@golang.org>
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
Reviewed-on: https://go-review.googlesource.com/c/go/+/341936
Reviewed-by: Bryan C. Mills <bcmills@google.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/cmd/compile/internal/ssa/stmtlines_test.go b/src/cmd/compile/internal/ssa/stmtlines_test.go
index a510d0b3d0..843db8c07e 100644
--- a/src/cmd/compile/internal/ssa/stmtlines_test.go
+++ b/src/cmd/compile/internal/ssa/stmtlines_test.go
@@ -2,6 +2,7 @@ package ssa_test
 
 import (
 	cmddwarf "cmd/internal/dwarf"
+	"cmd/internal/str"
 	"debug/dwarf"
 	"debug/elf"
 	"debug/macho"
@@ -57,7 +58,11 @@ func TestStmtLines(t *testing.T) {
 		if extld == "" {
 			extld = "gcc"
 		}
-		enabled, err := cmddwarf.IsDWARFEnabledOnAIXLd(extld)
+		extldArgs, err := str.SplitQuotedFields(extld)
+		if err != nil {
+			t.Fatal(err)
+		}
+		enabled, err := cmddwarf.IsDWARFEnabledOnAIXLd(extldArgs)
 		if err != nil {
 			t.Fatal(err)
 		}