cmd/compile: make gc debug flags collector a struct

gc debug flags are currently stored in a 256-long array, that is then
addressed using the ASCII numeric value of the flag itself (a quirk
inherited from the old C compiler). It is also a little wasteful,
since we only define 16 flags, and the other 240 array elements are
always empty.

This change makes Debug a struct, which also provides static checking
that we're not referencing flags that does not exist.

Change-Id: I2f0dfef2529325514b3398cf78635543cdf48fe0
Reviewed-on: https://go-review.googlesource.com/c/go/+/263539
Trust: Alberto Donizetti <alb.donizetti@gmail.com>
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/src/cmd/compile/internal/gc/export.go b/src/cmd/compile/internal/gc/export.go
index 839c2c2c75..c6917e0f81 100644
--- a/src/cmd/compile/internal/gc/export.go
+++ b/src/cmd/compile/internal/gc/export.go
@@ -31,7 +31,7 @@ func exportsym(n *Node) {
 	}
 	n.Sym.SetOnExportList(true)
 
-	if Debug['E'] != 0 {
+	if Debug.E != 0 {
 		fmt.Printf("export symbol %v\n", n.Sym)
 	}
 
@@ -150,7 +150,7 @@ func importconst(ipkg *types.Pkg, pos src.XPos, s *types.Sym, t *types.Type, val
 
 	n.SetVal(val)
 
-	if Debug['E'] != 0 {
+	if Debug.E != 0 {
 		fmt.Printf("import const %v %L = %v\n", s, t, val)
 	}
 }
@@ -166,7 +166,7 @@ func importfunc(ipkg *types.Pkg, pos src.XPos, s *types.Sym, t *types.Type) {
 	n.Func = new(Func)
 	t.SetNname(asTypesNode(n))
 
-	if Debug['E'] != 0 {
+	if Debug.E != 0 {
 		fmt.Printf("import func %v%S\n", s, t)
 	}
 }
@@ -179,7 +179,7 @@ func importvar(ipkg *types.Pkg, pos src.XPos, s *types.Sym, t *types.Type) {
 		return
 	}
 
-	if Debug['E'] != 0 {
+	if Debug.E != 0 {
 		fmt.Printf("import var %v %L\n", s, t)
 	}
 }
@@ -192,7 +192,7 @@ func importalias(ipkg *types.Pkg, pos src.XPos, s *types.Sym, t *types.Type) {
 		return
 	}
 
-	if Debug['E'] != 0 {
+	if Debug.E != 0 {
 		fmt.Printf("import type %v = %L\n", s, t)
 	}
 }