[dev.inline] cmd/compile: split mkpackage into separate functions

Previously, mkpackage jumbled together three unrelated tasks: handling
package declarations, clearing imports from processing previous source
files, and assigning a default value to outfile.

Change-Id: I1e124335768aeabfd1a6d9cc2499fbb980d951cf
Reviewed-on: https://go-review.googlesource.com/35124
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/gc/go.go

@@ -113,8 +113,6 @@ var sizeof_String int // runtime sizeof(String)
 
 var pragcgobuf string
 
-var infile string
-
 var outfile string
 var linkobj string
 

src/cmd/compile/internal/gc/main.go

@@ -218,6 +218,26 @@ func Main() {
 		usage()
 	}
 
+	if outfile == "" {
+		p := flag.Arg(0)
+		if i := strings.LastIndex(p, "/"); i >= 0 {
+			p = p[i+1:]
+		}
+		if runtime.GOOS == "windows" {
+			if i := strings.LastIndex(p, `\`); i >= 0 {
+				p = p[i+1:]
+			}
+		}
+		if i := strings.LastIndex(p, "."); i >= 0 {
+			p = p[:i]
+		}
+		suffix := ".o"
+		if writearchive {
+			suffix = ".a"
+		}
+		outfile = p + suffix
+	}
+
 	startProfile()
 
 	if flag_race {
@@ -306,7 +326,7 @@ func Main() {
 
 	timings.Start("fe", "parse")
 	var lines uint
-	for _, infile = range flag.Args() {
+	for _, infile := range flag.Args() {
 		block = 1
 		iota_ = -1000000
 		imported_unsafe = false
@@ -319,7 +339,6 @@ func Main() {
 	timings.AddEvent(int64(lines), "lines")
 
 	testdclstack()
-	mkpackage(localpkg.Name) // final import not used checks
 	finishUniverse()
 
 	typecheckok = true
@@ -900,6 +919,10 @@ func mkpackage(pkgname string) {
 		if pkgname != localpkg.Name {
 			yyerror("package %s; expected %s", pkgname, localpkg.Name)
 		}
+	}
+}
+
+func clearImports() {
 	for _, s := range localpkg.Syms {
 		if s.Def == nil {
 			continue
@@ -929,25 +952,4 @@ func mkpackage(pkgname string) {
 			continue
 		}
 	}
-	}
-
-	if outfile == "" {
-		p := infile
-		if i := strings.LastIndex(p, "/"); i >= 0 {
-			p = p[i+1:]
-		}
-		if runtime.GOOS == "windows" {
-			if i := strings.LastIndex(p, `\`); i >= 0 {
-				p = p[i+1:]
-			}
-		}
-		if i := strings.LastIndex(p, "."); i >= 0 {
-			p = p[:i]
-		}
-		suffix := ".o"
-		if writearchive {
-			suffix = ".a"
-		}
-		outfile = p + suffix
-	}
 }

src/cmd/compile/internal/gc/noder.go

@@ -70,6 +70,8 @@ func (p *noder) file(file *syntax.File) {
 	// TODO(gri) fix this once we switched permanently to the new
 	// position information.
 	lineno = MakePos(file.Pos().Base(), uint(file.Lines), 0)
+
+	clearImports()
 }
 
 func (p *noder) decls(decls []syntax.Decl) (l []*Node) {