stdout '^\tbuild\t-ldflags=example\.com/m=-w$'

go build -trimpath
go version -m m$GOEXE
stdout '\tbuild\t-trimpath=true$'

# gccgoflags are not added when gc is used, and vice versa.
# TODO: test gccgo.
go build -gccgoflags=all=UNUSED
go version -m m$GOEXE
! stdout gccgoflags

# Build and tool tags are added but not release tags.
# "race" is included with build tags but not "cgo".
go build -tags=a,b

	"fmt"
	"strings"
)

var (
	BuildAsmflags   PerPackageFlag // -asmflags
	BuildGcflags    PerPackageFlag // -gcflags
	BuildLdflags    PerPackageFlag // -ldflags
	BuildGccgoflags PerPackageFlag // -gccgoflags
)

// A PerPackageFlag is a command-line flag implementation (a flag.Value)
// that allows specifying different effective flags for different packages.
// See 'go help build' for more details about per-package flags.

				},
				Imports:    ximports,
				RawImports: rawXTestImports,

				Asmflags:       p.Internal.Asmflags,
				Gcflags:        p.Internal.Gcflags,
				Ldflags:        p.Internal.Ldflags,
				Gccgoflags:     p.Internal.Gccgoflags,
				Embed:          xtestEmbed,
				OrigImportPath: p.Internal.OrigImportPath,
				PGOProfile:     p.Internal.PGOProfile,
			},
		}
		if pxtestNeedsPtest {

	case "gccgo":
		if load.BuildGcflags.Present() {
			fmt.Println("go build: when using gccgo toolchain, please pass compiler flags using -gccgoflags, not -gcflags")
		}
		if load.BuildLdflags.Present() {
			fmt.Println("go build: when using gccgo toolchain, please pass linker flags using -gccgoflags, not -ldflags")
		}
	case "gc":
		if load.BuildGccgoflags.Present() {

					toPath = "." + toPath[len(base.Cwd()):]
				}
				args = append(args, "-ffile-prefix-map="+overlayPath+"="+toPath)
			}
		}
	}

	args = append(args, a.Package.Internal.Gccgoflags...)
	for _, f := range gofiles {
		f := mkAbs(p.Dir, f)
		// Overlay files if necessary.
		// See comment on gctoolchain.gc about overlay TODOs
		f, _ = fsys.OverlayPath(f)
		args = append(args, f)
	}

			buildmode = "archive"
		}
	}
	appendSetting("-buildmode", buildmode)
	appendSetting("-compiler", cfg.BuildContext.Compiler)
	if gccgoflags := BuildGccgoflags.String(); gccgoflags != "" && cfg.BuildContext.Compiler == "gccgo" {
		appendSetting("-gccgoflags", gccgoflags)
	}
	if gcflags := BuildGcflags.String(); gcflags != "" && cfg.BuildContext.Compiler == "gc" {
		appendSetting("-gcflags", gcflags)
	}

		// we let them use the flags specified for the command-line arguments.
		p := &load.Package{}
		p.Internal.CmdlinePkg = true
		p.Internal.Ldflags = load.BuildLdflags.For(p)
		p.Internal.Gccgoflags = load.BuildGccgoflags.For(p)

		// Add implicit dependencies to pkgs list.
		// Currently buildmode=shared forces external linking mode, and
		// external linking mode forces an import of runtime/cgo (and

			cgoCFLAGS = append(cgoCFLAGS, "-fsplit-stack")
		}
		cgoflags = append(cgoflags, "-gccgo")
		if pkgpath := gccgoPkgpath(p); pkgpath != "" {
			cgoflags = append(cgoflags, "-gccgopkgpath="+pkgpath)
		}
		if !BuildToolchain.(gccgoToolchain).supportsCgoIncomplete(b, a) {
			cgoflags = append(cgoflags, "-gccgo_define_cgoincomplete")
		}
	}

	switch cfg.BuildBuildmode {

	tg.runFail("build", "x")
	tg.grepStderr("invalid input file name \"-y.go\"", "did not reject -y.go")
	tg.must(os.Remove(tg.path("src/x/-y.go")))

	if runtime.Compiler == "gccgo" {
		tg.runFail("build", "-gccgoflags=all=@x", "x")
	} else {
		tg.runFail("build", "-gcflags=all=@x", "x")
	}
	tg.grepStderr("invalid command-line argument @x in command", "did not reject @x during exec")

//		cannot be included due to a missing tool or ambiguous directory structure.
//	-compiler name
//		name of compiler to use, as in runtime.Compiler (gccgo or gc).
//	-gccgoflags '[pattern=]arg list'
//		arguments to pass on each gccgo compiler/linker invocation.
//	-gcflags '[pattern=]arg list'
//		arguments to pass on each go tool compile invocation.
//	-installsuffix suffix