cmd/link: update flag doc

Update the go doc for linker flags. Remove flags that no longer
exist. Also remove flags that are intended for debugging the
linker from user docs. Add -aslr to the doc.

The -n flag does nothing except print a nearly useless message on
XCOFF linking. Deprecate it.

Fixes #64476.

Change-Id: I518c9c6cc009eae50b7c11308348524ad6a62b69
Reviewed-on: https://go-review.googlesource.com/c/go/+/546615
Reviewed-by: Than McIntosh <thanm@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/cmd/link/doc.go

@@ -43,10 +43,10 @@ Flags:
 		or initialized to a constant string expression. -X will not work if the initializer makes
 		a function call or refers to other variables.
 		Note that before Go 1.5 this option took two separate arguments.
-	-a
-		Disassemble output.
 	-asan
 		Link with C/C++ address sanitizer support.
+	-aslr
+		Enable ASLR for buildmode=c-shared on windows (default true).
 	-buildid id
 		Record id as Go toolchain build id.
 	-buildmode mode
@@ -64,8 +64,6 @@ Flags:
 		The dynamic header is on by default, even without any
 		references to dynamic libraries, because many common
 		system tools now assume the presence of the header.
-	-debugtramp int
-		Debug trampolines.
 	-dumpdep
 		Dump symbol dependency graph.
 	-extar ar
@@ -104,8 +102,6 @@ Flags:
 		Set runtime.MemProfileRate to rate.
 	-msan
 		Link with C/C++ memory sanitizer support.
-	-n
-		Dump symbol table.
 	-o file
 		Write output to file (default a.out, or a.out.exe on Windows).
 	-pluginpath path
@@ -116,13 +112,9 @@ Flags:
 		Link with race detection libraries.
 	-s
 		Omit the symbol table and debug information.
-	-shared
-		Generated shared object (implies -linkmode external; experimental).
 	-tmpdir dir
 		Write temporary files to dir.
 		Temporary files are only used in external linking mode.
-	-u
-		Reject unsafe packages.
 	-v
 		Print trace of linker operations.
 	-w

src/cmd/link/internal/ld/main.go

@@ -90,7 +90,7 @@ var (
 	flagF             = flag.Bool("f", false, "ignore version mismatch")
 	flagG             = flag.Bool("g", false, "disable go package data checks")
 	flagH             = flag.Bool("h", false, "halt on error")
-	flagN             = flag.Bool("n", false, "dump symbol table")
+	flagN             = flag.Bool("n", false, "no-op (deprecated)")
 	FlagS             = flag.Bool("s", false, "disable symbol table")
 	flag8             bool // use 64-bit addresses in symbol table
 	flagInterpreter   = flag.String("I", "", "use `linker` as ELF dynamic linker")

src/cmd/link/internal/ld/xcoff.go

@@ -1140,7 +1140,7 @@ func (f *xcoffFile) asmaixsym(ctxt *Link) {
 		putaixsym(ctxt, s, TextSym)
 	}
 
-	if ctxt.Debugvlog != 0 || *flagN {
+	if ctxt.Debugvlog != 0 {
 		ctxt.Logf("symsize = %d\n", uint32(symSize))
 	}
 	xfile.updatePreviousFile(ctxt, true)