Add race detector support

Fixes #96

Adds the race detector you all know and love to gb.

Todo:
- [ ] Add support for rebuilding stdlib if -race support is not present.
- [ ] Add interlocks to restrict the race detector to certain amd64 for freebsd, linux, darwin, and linux.
- [ ] Make all binaries dependant on runtime/race.
- [ ] Add tests at cmd/gb as well as gb and gb/test.

cmd/gb/gb_test.go

@@ -80,6 +80,7 @@ func TestMain(m *testing.M) {
 	// Don't let these environment variables confuse the test.
 	os.Unsetenv("GOBIN")
 	os.Unsetenv("GOPATH")
+	os.Unsetenv("DEBUG")
 
 	r := m.Run()
 	os.Exit(r)

context.go

@@ -76,11 +76,30 @@ func Tags(tags ...string) func(*Context) error {
 	}
 }
 
+// Gcflags appends flags to the list passed to the compiler.
+func Gcflags(flags ...string) func(*Context) error {
+	return func(c *Context) error {
+		c.gcflags = append(c.gcflags, flags...)
+		return nil
+	}
+}
+
+// Ldflags appends flags to the list passed to the linker.
+func Ldflags(flags ...string) func(*Context) error {
+	return func(c *Context) error {
+		c.ldflags = append(c.ldflags, flags...)
+		return nil
+	}
+}
+
 // WithRace enables the race detector and adds the tag "race" to
 // the Context build tags.
 func WithRace(c *Context) error {
 	c.race = true
-	return Tags("race")(c)
+	Tags("race")(c)
+	Gcflags("-race")(c)
+	Ldflags("-race")(c)
+	return nil
 }
 
 // NewContext returns a new build context from this project.
@@ -149,22 +168,6 @@ func (p *Project) NewContext(opts ...func(*Context) error) (*Context, error) {
 	return &ctx, nil
 }
 
-// Gcflags sets options passed to the compiler.
-func Gcflags(flags ...string) func(*Context) error {
-	return func(c *Context) error {
-		c.gcflags = flags
-		return nil
-	}
-}
-
-// Ldflags sets options passed to the linker.
-func Ldflags(flags ...string) func(*Context) error {
-	return func(c *Context) error {
-		c.ldflags = flags
-		return nil
-	}
-}
-
 // IncludePaths returns the include paths visible in this context.
 func (c *Context) IncludePaths() []string {
 	return []string{

context_test.go

@@ -122,18 +122,36 @@ func TestContextOptions(t *testing.T) {
 		ctx:    Context{buildtags: []string{"foo"}},
 		fn:     Tags("bar"),
 		expect: matches(Context{buildtags: []string{"foo", "bar"}}),
+	}, {
+		fn:     Gcflags("foo"),
+		expect: matches(Context{gcflags: []string{"foo"}}),
+	}, {
+		ctx:    Context{gcflags: []string{"foo"}},
+		fn:     Gcflags("bar"),
+		expect: matches(Context{gcflags: []string{"foo", "bar"}}),
+	}, {
+		fn:     Ldflags("foo"),
+		expect: matches(Context{ldflags: []string{"foo"}}),
+	}, {
+		ctx:    Context{ldflags: []string{"foo"}},
+		fn:     Ldflags("bar"),
+		expect: matches(Context{ldflags: []string{"foo", "bar"}}),
 	}, {
 		fn: WithRace,
 		expect: matches(Context{
 			buildtags: []string{"race"},
 			race:      true,
+			gcflags:   []string{"-race"},
+			ldflags:   []string{"-race"},
 		}),
 	}, {
 		ctx: Context{buildtags: []string{"zzz"}},
 		fn:  WithRace,
 		expect: matches(Context{
 			buildtags: []string{"zzz", "race"},
 			race:      true,
+			gcflags:   []string{"-race"},
+			ldflags:   []string{"-race"},
 		}),
 	}}