cmd/compile: record original and absolute file names for line directives

Also, with this change, error locations don't print absolute positions
in [] brackets following positions relative to line directives. To get
the absolute positions as well, specify the -L flag.

Fixes #22660.

Change-Id: I9ecfa254f053defba9c802222874155fa12fee2c
Reviewed-on: https://go-review.googlesource.com/77090
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

10 files changed, 32 insertions, 26 deletions

diff --git a/src/cmd/asm/internal/lex/input.go b/src/cmd/asm/internal/lex/input.go
index ddfcddf36d..666611e179 100644
--- a/src/cmd/asm/internal/lex/input.go
+++ b/src/cmd/asm/internal/lex/input.go
@@ -13,6 +13,7 @@ import (
 	"text/scanner"
 
 	"cmd/asm/internal/flags"
+	"cmd/internal/objabi"
 	"cmd/internal/src"
 )
 
@@ -454,7 +455,7 @@ func (in *Input) line() {
 		in.Error("unexpected token at end of #line: ", tok)
 	}
 	pos := src.MakePos(in.Base(), uint(in.Line()), uint(in.Col()))
-	in.Stack.SetBase(src.NewLinePragmaBase(pos, file, uint(line)))
+	in.Stack.SetBase(src.NewLinePragmaBase(pos, file, objabi.AbsFile(objabi.WorkingDir(), file, *flags.TrimPath), uint(line)))
 }
 
 // #undef processing
diff --git a/src/cmd/compile/internal/gc/main.go b/src/cmd/compile/internal/gc/main.go
index 6f633a494f..be2fe552f6 100644
--- a/src/cmd/compile/internal/gc/main.go
+++ b/src/cmd/compile/internal/gc/main.go
@@ -192,6 +192,7 @@ func Main(archInit func(*Arch)) {
 	objabi.Flagcount("E", "debug symbol export", &Debug['E'])
 	objabi.Flagfn1("I", "add `directory` to import search path", addidir)
 	objabi.Flagcount("K", "debug missing line numbers", &Debug['K'])
+	objabi.Flagcount("L", "show full file names in error messages", &Debug['L'])
 	objabi.Flagcount("N", "disable optimizations", &Debug['N'])
 	flag.BoolVar(&Debug_asm, "S", false, "print assembly listing")
 	objabi.AddVersionFlag() // -V
diff --git a/src/cmd/compile/internal/gc/subr.go b/src/cmd/compile/internal/gc/subr.go
index b7d530c98c..81441ba700 100644
--- a/src/cmd/compile/internal/gc/subr.go
+++ b/src/cmd/compile/internal/gc/subr.go
@@ -93,7 +93,7 @@ func hcrash() {
 }
 
 func linestr(pos src.XPos) string {
-	return Ctxt.OutermostPos(pos).Format(Debug['C'] == 0)
+	return Ctxt.OutermostPos(pos).Format(Debug['C'] == 0, Debug['L'] == 1)
 }
 
 // lasterror keeps track of the most recently issued error.
diff --git a/src/cmd/compile/internal/syntax/parser.go b/src/cmd/compile/internal/syntax/parser.go
index 7047266a70..ff3e769864 100644
--- a/src/cmd/compile/internal/syntax/parser.go
+++ b/src/cmd/compile/internal/syntax/parser.go
@@ -80,11 +80,12 @@ func (p *parser) updateBase(line, col uint, text string) {
 		p.error_at(p.pos_at(line, col+uint(i+1)), "invalid line number: "+nstr)
 		return
 	}
-	absFile := text[:i]
+	filename := text[:i]
+	absFilename := filename
 	if p.fileh != nil {
-		absFile = p.fileh(absFile)
+		absFilename = p.fileh(filename)
 	}
-	p.base = src.NewLinePragmaBase(src.MakePos(p.base.Pos().Base(), line, col), absFile, uint(n))
+	p.base = src.NewLinePragmaBase(src.MakePos(p.base.Pos().Base(), line, col), filename, absFilename, uint(n))
 }
 
 func (p *parser) got(tok token) bool {
diff --git a/src/cmd/compile/internal/syntax/parser_test.go b/src/cmd/compile/internal/syntax/parser_test.go
index 0478088ec8..309f1333f4 100644
--- a/src/cmd/compile/internal/syntax/parser_test.go
+++ b/src/cmd/compile/internal/syntax/parser_test.go
@@ -221,7 +221,7 @@ func TestLineDirectives(t *testing.T) {
 		if msg := perr.Msg; msg != test.msg {
 			t.Errorf("%s: got msg = %q; want %q", test.src, msg, test.msg)
 		}
-		if filename := perr.Pos.RelFilename(); filename != test.filename {
+		if filename := perr.Pos.AbsFilename(); filename != test.filename {
 			t.Errorf("%s: got filename = %q; want %q", test.src, filename, test.filename)
 		}
 		if line := perr.Pos.RelLine(); line != test.line+linebase {
diff --git a/src/cmd/internal/obj/line_test.go b/src/cmd/internal/obj/line_test.go
index 6b21abecd2..f159a65e2b 100644
--- a/src/cmd/internal/obj/line_test.go
+++ b/src/cmd/internal/obj/line_test.go
@@ -17,7 +17,7 @@ func TestLinkgetlineFromPos(t *testing.T) {
 
 	afile := src.NewFileBase("a.go", "a.go")
 	bfile := src.NewFileBase("b.go", "/foo/bar/b.go")
-	lfile := src.NewLinePragmaBase(src.MakePos(afile, 7, 0), "linedir", 100)
+	lfile := src.NewLinePragmaBase(src.MakePos(afile, 7, 0), "linedir", "linedir", 100)
 
 	var tests = []struct {
 		pos  src.Pos
diff --git a/src/cmd/internal/obj/util.go b/src/cmd/internal/obj/util.go
index f1ac1a8808..867c69f3ef 100644
--- a/src/cmd/internal/obj/util.go
+++ b/src/cmd/internal/obj/util.go
@@ -15,7 +15,7 @@ const REG_NONE = 0
 
 // Line returns a string containing the filename and line number for p
 func (p *Prog) Line() string {
-	return p.Ctxt.OutermostPos(p.Pos).Format(false)
+	return p.Ctxt.OutermostPos(p.Pos).Format(false, true)
 }
 
 // LineNumber returns a string containing the line number for p's position
diff --git a/src/cmd/internal/src/pos.go b/src/cmd/internal/src/pos.go
index a1ea3fcdac..10fa924c0b 100644
--- a/src/cmd/internal/src/pos.go
+++ b/src/cmd/internal/src/pos.go
@@ -79,15 +79,15 @@ func (p Pos) AbsFilename() string { return p.base.AbsFilename() }
 func (p Pos) SymFilename() string { return p.base.SymFilename() }
 
 func (p Pos) String() string {
-	return p.Format(true)
+	return p.Format(true, true)
 }
 
 // Format formats a position as "filename:line" or "filename:line:column",
-// controlled by the showCol flag.
-// If the position is relative to a line directive, the original position
-// is appended in square brackets without column (since the column doesn't
-// change).
-func (p Pos) Format(showCol bool) string {
+// controlled by the showCol flag. A position relative to a line directive
+// is always formatted without column information. In that case, if showOrig
+// is set, the original position (again controlled by showCol) is appended
+// in square brackets: "filename:line[origfile:origline:origcolumn]".
+func (p Pos) Format(showCol, showOrig bool) string {
 	if !p.IsKnown() {
 		return "<unknown line number>"
 	}
@@ -105,8 +105,11 @@ func (p Pos) Format(showCol bool) string {
 	// that's provided via a line directive).
 	// TODO(gri) This may not be true if we have an inlining base.
 	// We may want to differentiate at some point.
-	return format(p.RelFilename(), p.RelLine(), 0, false) +
-		"[" + format(p.Filename(), p.Line(), p.Col(), showCol) + "]"
+	s := format(p.RelFilename(), p.RelLine(), 0, false)
+	if showOrig {
+		s += "[" + format(p.Filename(), p.Line(), p.Col(), showCol) + "]"
+	}
+	return s
 }
 
 // format formats a (filename, line, col) tuple as "filename:line" (showCol
@@ -155,8 +158,8 @@ func NewFileBase(filename, absFilename string) *PosBase {
 // NewLinePragmaBase returns a new *PosBase for a line pragma of the form
 //      //line filename:line
 // at position pos.
-func NewLinePragmaBase(pos Pos, filename string, line uint) *PosBase {
-	return &PosBase{pos, filename, filename, FileSymPrefix + filename, line - 1, -1}
+func NewLinePragmaBase(pos Pos, filename, absFilename string, line uint) *PosBase {
+	return &PosBase{pos, filename, absFilename, FileSymPrefix + absFilename, line - 1, -1}
 }
 
 // NewInliningBase returns a copy of the old PosBase with the given inlining
diff --git a/src/cmd/internal/src/pos_test.go b/src/cmd/internal/src/pos_test.go
index a101bc10b1..b06d382536 100644
--- a/src/cmd/internal/src/pos_test.go
+++ b/src/cmd/internal/src/pos_test.go
@@ -12,16 +12,16 @@ import (
 func TestPos(t *testing.T) {
 	f0 := NewFileBase("", "")
 	f1 := NewFileBase("f1", "f1")
-	f2 := NewLinePragmaBase(Pos{}, "f2", 10)
-	f3 := NewLinePragmaBase(MakePos(f1, 10, 1), "f3", 100)
-	f4 := NewLinePragmaBase(MakePos(f3, 10, 1), "f4", 100)
+	f2 := NewLinePragmaBase(Pos{}, "f2", "f2", 10)
+	f3 := NewLinePragmaBase(MakePos(f1, 10, 1), "f3", "f3", 100)
+	f4 := NewLinePragmaBase(MakePos(f3, 10, 1), "f4", "f4", 100)
 
 	// line directives from issue #19392
 	fp := NewFileBase("p.go", "p.go")
-	fc := NewLinePragmaBase(MakePos(fp, 3, 0), "c.go", 10)
-	ft := NewLinePragmaBase(MakePos(fp, 6, 0), "t.go", 20)
-	fv := NewLinePragmaBase(MakePos(fp, 9, 0), "v.go", 30)
-	ff := NewLinePragmaBase(MakePos(fp, 12, 0), "f.go", 40)
+	fc := NewLinePragmaBase(MakePos(fp, 3, 0), "c.go", "c.go", 10)
+	ft := NewLinePragmaBase(MakePos(fp, 6, 0), "t.go", "t.go", 20)
+	fv := NewLinePragmaBase(MakePos(fp, 9, 0), "v.go", "v.go", 30)
+	ff := NewLinePragmaBase(MakePos(fp, 12, 0), "f.go", "f.go", 40)
 
 	for _, test := range []struct {
 		pos    Pos
diff --git a/src/cmd/internal/src/xpos_test.go b/src/cmd/internal/src/xpos_test.go
index 4cfeedcd05..8ac9c9dc4e 100644
--- a/src/cmd/internal/src/xpos_test.go
+++ b/src/cmd/internal/src/xpos_test.go
@@ -19,7 +19,7 @@ func TestNoXPos(t *testing.T) {
 func TestConversion(t *testing.T) {
 	b1 := NewFileBase("b1", "b1")
 	b2 := NewFileBase("b2", "b2")
-	b3 := NewLinePragmaBase(MakePos(b1, 10, 0), "b3", 123)
+	b3 := NewLinePragmaBase(MakePos(b1, 10, 0), "b3", "b3", 123)
 
 	var tab PosTable
 	for _, want := range []Pos{