cmd/asm: improve assembler error messages

Provide file/line numbers for errors when we have them.
Make the assembler error text closer to the equivalent errors from the compiler.

Abort further processing when we come across errors.
Fixes #53994

Change-Id: I4d6a037d6d713c1329923fce4c1189b5609f3660
Reviewed-on: https://go-review.googlesource.com/c/go/+/455276
Reviewed-by: Keith Randall <[email protected]>
Run-TryBot: Keith Randall <[email protected]>
Auto-Submit: Keith Randall <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: randall77

src/cmd/asm/internal/asm/asm.go

@@ -297,7 +297,7 @@ func (p *Parser) asmGlobl(operands [][]lex.Token) {
 	}
 
 	// log.Printf("GLOBL %s %d, $%d", name, flag, size)
-	p.ctxt.Globl(nameAddr.Sym, addr.Offset, int(flag))
+	p.ctxt.GloblPos(nameAddr.Sym, addr.Offset, int(flag), p.pos())
 }
 
 // asmPCData assembles a PCDATA pseudo-op.

src/cmd/asm/internal/asm/endtoend_test.go

@@ -381,6 +381,10 @@ func TestGoBuildErrors(t *testing.T) {
 	testErrors(t, "amd64", "buildtagerror")
 }
 
+func TestGenericErrors(t *testing.T) {
+	testErrors(t, "amd64", "duperror")
+}
+
 func TestARMErrors(t *testing.T) {
 	testErrors(t, "arm", "armerror")
 }

src/cmd/asm/internal/asm/testdata/duperror.s

@@ -0,0 +1,14 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+TEXT foo(SB), 0, $0
+	RET
+TEXT foo(SB), 0, $0 // ERROR "symbol foo redeclared"
+	RET
+
+GLOBL bar(SB), 0, $8
+GLOBL bar(SB), 0, $8 // ERROR "symbol bar redeclared"
+
+DATA bar+0(SB)/8, $0
+DATA bar+0(SB)/8, $0 // ERROR "overlapping DATA entry for bar"

src/cmd/internal/obj/plist.go

@@ -58,12 +58,12 @@ func Flushplist(ctxt *Link, plist *Plist, newprog ProgAlloc, myimportpath string
 			switch p.To.Sym.Name {
 			case "go_args_stackmap":
 				if p.From.Type != TYPE_CONST || p.From.Offset != objabi.FUNCDATA_ArgsPointerMaps {
-					ctxt.Diag("FUNCDATA use of go_args_stackmap(SB) without FUNCDATA_ArgsPointerMaps")
+					ctxt.Diag("%s: FUNCDATA use of go_args_stackmap(SB) without FUNCDATA_ArgsPointerMaps", p.Pos)
 				}
 				p.To.Sym = ctxt.LookupDerived(curtext, curtext.Name+".args_stackmap")
 			case "no_pointers_stackmap":
 				if p.From.Type != TYPE_CONST || p.From.Offset != objabi.FUNCDATA_LocalsPointerMaps {
-					ctxt.Diag("FUNCDATA use of no_pointers_stackmap(SB) without FUNCDATA_LocalsPointerMaps")
+					ctxt.Diag("%s: FUNCDATA use of no_pointers_stackmap(SB) without FUNCDATA_LocalsPointerMaps", p.Pos)
 				}
 				// funcdata for functions with no local variables in frame.
 				// Define two zero-length bitmaps, because the same index is used
@@ -166,11 +166,13 @@ func (ctxt *Link) InitTextSym(s *LSym, flag int, start src.XPos) {
 		return
 	}
 	if s.Func() != nil {
-		ctxt.Diag("InitTextSym double init for %s", s.Name)
+		ctxt.Diag("%s: symbol %s redeclared\n\t%s: other declaration of symbol %s", ctxt.PosTable.Pos(start), s.Name, ctxt.PosTable.Pos(s.Func().Text.Pos), s.Name)
+		return
 	}
 	s.NewFuncInfo()
 	if s.OnList() {
-		ctxt.Diag("symbol %s listed multiple times", s.Name)
+		ctxt.Diag("%s: symbol %s redeclared", ctxt.PosTable.Pos(start), s.Name)
+		return
 	}
 
 	// startLine should be the same line number that would be displayed via
@@ -210,8 +212,12 @@ func (ctxt *Link) toFuncFlag(flag int) objabi.FuncFlag {
 }
 
 func (ctxt *Link) Globl(s *LSym, size int64, flag int) {
+	ctxt.GloblPos(s, size, flag, src.NoXPos)
+}
+func (ctxt *Link) GloblPos(s *LSym, size int64, flag int, pos src.XPos) {
 	if s.OnList() {
-		ctxt.Diag("symbol %s listed multiple times", s.Name)
+		// TODO: print where the first declaration was.
+		ctxt.Diag("%s: symbol %s redeclared", ctxt.PosTable.Pos(pos), s.Name)
 	}
 	s.Set(AttrOnList, true)
 	ctxt.Data = append(ctxt.Data, s)