cmd/compile, cmd/compile/internal/syntax: print relative column info

This change enables printing of relative column information if a
prior line directive specified a valid column. If there was no
line directive, or the line directive didn't specify a column
(or the -C flag is specified), no column information is shown in
file positions.

Implementation: Column values (and line values, for that matter)
that are zero are interpreted as "unknown". A line directive that
doesn't specify a column records that as a zero column in the
respective PosBase data structure. When computing relative columns,
a relative value is zero of the base's column value is zero.
When formatting a position, a zero column value is not printed.

To make this work without special cases, the PosBase for a file
is given a concrete (non-0:0) position 1:1 with the PosBase's
line and column also being 1:1. In other words, at the position
1:1 of a file, it's relative positions are starting with 1:1 as
one would expect.

In the package syntax, this requires self-recursive PosBases for
file bases, matching what cmd/internal/src.PosBase was already
doing. In src.PosBase, file and inlining bases also need to be
based at 1:1 to indicate "known" positions.

This change completes the cmd/compiler part of the issue below.

Fixes #22662.

Change-Id: I6c3d2dee26709581fba0d0261b1d12e93f1cba1a
Reviewed-on: https://go-review.googlesource.com/97375
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

1 files changed, 85 insertions, 85 deletions

diff --git a/src/cmd/compile/internal/syntax/parser_test.go b/src/cmd/compile/internal/syntax/parser_test.go
index c253a5c345..3cf55defc7 100644
--- a/src/cmd/compile/internal/syntax/parser_test.go
+++ b/src/cmd/compile/internal/syntax/parser_test.go
@@ -193,113 +193,113 @@ func TestLineDirectives(t *testing.T) {
 	for _, test := range []struct {
 		src, msg  string
 		filename  string
-		line, col uint // 0-based
+		line, col uint // 1-based; 0 means unknown
 	}{
 		// ignored //line directives
-		{"//\n", valid, filename, 1, 0},            // no directive
-		{"//line\n", valid, filename, 1, 0},        // missing colon
-		{"//line foo\n", valid, filename, 1, 0},    // missing colon
-		{"  //line foo:\n", valid, filename, 1, 0}, // not a line start
-		{"//  line foo:\n", valid, filename, 1, 0}, // space between // and line
+		{"//\n", valid, filename, 2, 1},            // no directive
+		{"//line\n", valid, filename, 2, 1},        // missing colon
+		{"//line foo\n", valid, filename, 2, 1},    // missing colon
+		{"  //line foo:\n", valid, filename, 2, 1}, // not a line start
+		{"//  line foo:\n", valid, filename, 2, 1}, // space between // and line
 
 		// invalid //line directives with one colon
-		{"//line :\n", "invalid line number: ", filename, 0, 8},
-		{"//line :x\n", "invalid line number: x", filename, 0, 8},
-		{"//line foo :\n", "invalid line number: ", filename, 0, 12},
-		{"//line foo:x\n", "invalid line number: x", filename, 0, 11},
-		{"//line foo:0\n", "invalid line number: 0", filename, 0, 11},
-		{"//line foo:1 \n", "invalid line number: 1 ", filename, 0, 11},
-		{"//line foo:-12\n", "invalid line number: -12", filename, 0, 11},
-		{"//line C:foo:0\n", "invalid line number: 0", filename, 0, 13},
-		{fmt.Sprintf("//line foo:%d\n", tooLarge), fmt.Sprintf("invalid line number: %d", tooLarge), filename, 0, 11},
+		{"//line :\n", "invalid line number: ", filename, 1, 9},
+		{"//line :x\n", "invalid line number: x", filename, 1, 9},
+		{"//line foo :\n", "invalid line number: ", filename, 1, 13},
+		{"//line foo:x\n", "invalid line number: x", filename, 1, 12},
+		{"//line foo:0\n", "invalid line number: 0", filename, 1, 12},
+		{"//line foo:1 \n", "invalid line number: 1 ", filename, 1, 12},
+		{"//line foo:-12\n", "invalid line number: -12", filename, 1, 12},
+		{"//line C:foo:0\n", "invalid line number: 0", filename, 1, 14},
+		{fmt.Sprintf("//line foo:%d\n", tooLarge), fmt.Sprintf("invalid line number: %d", tooLarge), filename, 1, 12},
 
 		// invalid //line directives with two colons
-		{"//line ::\n", "invalid line number: ", filename, 0, 9},
-		{"//line ::x\n", "invalid line number: x", filename, 0, 9},
-		{"//line foo::123abc\n", "invalid line number: 123abc", filename, 0, 12},
-		{"//line foo::0\n", "invalid line number: 0", filename, 0, 12},
-		{"//line foo:0:1\n", "invalid line number: 0", filename, 0, 11},
+		{"//line ::\n", "invalid line number: ", filename, 1, 10},
+		{"//line ::x\n", "invalid line number: x", filename, 1, 10},
+		{"//line foo::123abc\n", "invalid line number: 123abc", filename, 1, 13},
+		{"//line foo::0\n", "invalid line number: 0", filename, 1, 13},
+		{"//line foo:0:1\n", "invalid line number: 0", filename, 1, 12},
 
-		{"//line :123:0\n", "invalid column number: 0", filename, 0, 12},
-		{"//line foo:123:0\n", "invalid column number: 0", filename, 0, 15},
-		{fmt.Sprintf("//line foo:10:%d\n", tooLarge), fmt.Sprintf("invalid column number: %d", tooLarge), filename, 0, 14},
+		{"//line :123:0\n", "invalid column number: 0", filename, 1, 13},
+		{"//line foo:123:0\n", "invalid column number: 0", filename, 1, 16},
+		{fmt.Sprintf("//line foo:10:%d\n", tooLarge), fmt.Sprintf("invalid column number: %d", tooLarge), filename, 1, 15},
 
 		// effect of valid //line directives on lines
-		{"//line foo:123\n   foo", valid, "foo", 123 - linebase, 3},
-		{"//line  foo:123\n   foo", valid, " foo", 123 - linebase, 3},
-		{"//line foo:123\n//line bar:345\nfoo", valid, "bar", 345 - linebase, 0},
-		{"//line C:foo:123\n", valid, "C:foo", 123 - linebase, 0},
-		{"//line /src/a/a.go:123\n   foo", valid, "/src/a/a.go", 123 - linebase, 3},
-		{"//line :x:1\n", valid, ":x", 1 - linebase, 0},
-		{"//line foo ::1\n", valid, "foo :", 1 - linebase, 0},
-		{"//line foo:123abc:1\n", valid, "foo:123abc", 0, 0},
-		{"//line foo :123:1\n", valid, "foo ", 123 - linebase, 0},
-		{"//line ::123\n", valid, ":", 123 - linebase, 0},
+		{"//line foo:123\n   foo", valid, "foo", 123, 0},
+		{"//line  foo:123\n   foo", valid, " foo", 123, 0},
+		{"//line foo:123\n//line bar:345\nfoo", valid, "bar", 345, 0},
+		{"//line C:foo:123\n", valid, "C:foo", 123, 0},
+		{"//line /src/a/a.go:123\n   foo", valid, "/src/a/a.go", 123, 0},
+		{"//line :x:1\n", valid, ":x", 1, 0},
+		{"//line foo ::1\n", valid, "foo :", 1, 0},
+		{"//line foo:123abc:1\n", valid, "foo:123abc", 1, 0},
+		{"//line foo :123:1\n", valid, "foo ", 123, 1},
+		{"//line ::123\n", valid, ":", 123, 0},
 
 		// effect of valid //line directives on columns
-		{"//line :x:1:10\n", valid, ":x", 1 - linebase, 10 - colbase},
-		{"//line foo ::1:2\n", valid, "foo :", 1 - linebase, 2 - colbase},
-		{"//line foo:123abc:1:1000\n", valid, "foo:123abc", 1 - linebase, 1000 - colbase},
-		{"//line foo :123:1000\n\n", valid, "foo ", 124 - linebase, 0},
-		{"//line ::123:1234\n", valid, ":", 123 - linebase, 1234 - colbase},
+		{"//line :x:1:10\n", valid, ":x", 1, 10},
+		{"//line foo ::1:2\n", valid, "foo :", 1, 2},
+		{"//line foo:123abc:1:1000\n", valid, "foo:123abc", 1, 1000},
+		{"//line foo :123:1000\n\n", valid, "foo ", 124, 1},
+		{"//line ::123:1234\n", valid, ":", 123, 1234},
 
 		// //line directives with omitted filenames lead to empty filenames
-		{"//line :10\n", valid, "", 10 - linebase, 0},
-		{"//line :10:20\n", valid, filename, 10 - linebase, 20 - colbase},
-		{"//line bar:1\n//line :10\n", valid, "", 10 - linebase, 0},
-		{"//line bar:1\n//line :10:20\n", valid, "bar", 10 - linebase, 20 - colbase},
+		{"//line :10\n", valid, "", 10, 0},
+		{"//line :10:20\n", valid, filename, 10, 20},
+		{"//line bar:1\n//line :10\n", valid, "", 10, 0},
+		{"//line bar:1\n//line :10:20\n", valid, "bar", 10, 20},
 
 		// ignored /*line directives
-		{"/**/", valid, filename, 0, 4},             // no directive
-		{"/*line*/", valid, filename, 0, 8},         // missing colon
-		{"/*line foo*/", valid, filename, 0, 12},    // missing colon
-		{"  //line foo:*/", valid, filename, 0, 15}, // not a line start
-		{"/*  line foo:*/", valid, filename, 0, 15}, // space between // and line
+		{"/**/", valid, filename, 1, 5},             // no directive
+		{"/*line*/", valid, filename, 1, 9},         // missing colon
+		{"/*line foo*/", valid, filename, 1, 13},    // missing colon
+		{"  //line foo:*/", valid, filename, 1, 16}, // not a line start
+		{"/*  line foo:*/", valid, filename, 1, 16}, // space between // and line
 
 		// invalid /*line directives with one colon
-		{"/*line :*/", "invalid line number: ", filename, 0, 8},
-		{"/*line :x*/", "invalid line number: x", filename, 0, 8},
-		{"/*line foo :*/", "invalid line number: ", filename, 0, 12},
-		{"/*line foo:x*/", "invalid line number: x", filename, 0, 11},
-		{"/*line foo:0*/", "invalid line number: 0", filename, 0, 11},
-		{"/*line foo:1 */", "invalid line number: 1 ", filename, 0, 11},
-		{"/*line C:foo:0*/", "invalid line number: 0", filename, 0, 13},
-		{fmt.Sprintf("/*line foo:%d*/", tooLarge), fmt.Sprintf("invalid line number: %d", tooLarge), filename, 0, 11},
+		{"/*line :*/", "invalid line number: ", filename, 1, 9},
+		{"/*line :x*/", "invalid line number: x", filename, 1, 9},
+		{"/*line foo :*/", "invalid line number: ", filename, 1, 13},
+		{"/*line foo:x*/", "invalid line number: x", filename, 1, 12},
+		{"/*line foo:0*/", "invalid line number: 0", filename, 1, 12},
+		{"/*line foo:1 */", "invalid line number: 1 ", filename, 1, 12},
+		{"/*line C:foo:0*/", "invalid line number: 0", filename, 1, 14},
+		{fmt.Sprintf("/*line foo:%d*/", tooLarge), fmt.Sprintf("invalid line number: %d", tooLarge), filename, 1, 12},
 
 		// invalid /*line directives with two colons
-		{"/*line ::*/", "invalid line number: ", filename, 0, 9},
-		{"/*line ::x*/", "invalid line number: x", filename, 0, 9},
-		{"/*line foo::123abc*/", "invalid line number: 123abc", filename, 0, 12},
-		{"/*line foo::0*/", "invalid line number: 0", filename, 0, 12},
-		{"/*line foo:0:1*/", "invalid line number: 0", filename, 0, 11},
+		{"/*line ::*/", "invalid line number: ", filename, 1, 10},
+		{"/*line ::x*/", "invalid line number: x", filename, 1, 10},
+		{"/*line foo::123abc*/", "invalid line number: 123abc", filename, 1, 13},
+		{"/*line foo::0*/", "invalid line number: 0", filename, 1, 13},
+		{"/*line foo:0:1*/", "invalid line number: 0", filename, 1, 12},
 
-		{"/*line :123:0*/", "invalid column number: 0", filename, 0, 12},
-		{"/*line foo:123:0*/", "invalid column number: 0", filename, 0, 15},
-		{fmt.Sprintf("/*line foo:10:%d*/", tooLarge), fmt.Sprintf("invalid column number: %d", tooLarge), filename, 0, 14},
+		{"/*line :123:0*/", "invalid column number: 0", filename, 1, 13},
+		{"/*line foo:123:0*/", "invalid column number: 0", filename, 1, 16},
+		{fmt.Sprintf("/*line foo:10:%d*/", tooLarge), fmt.Sprintf("invalid column number: %d", tooLarge), filename, 1, 15},
 
 		// effect of valid /*line directives on lines
-		{"/*line foo:123*/   foo", valid, "foo", 123 - linebase, 3},
-		{"/*line foo:123*/\n//line bar:345\nfoo", valid, "bar", 345 - linebase, 0},
-		{"/*line C:foo:123*/", valid, "C:foo", 123 - linebase, 0},
-		{"/*line /src/a/a.go:123*/   foo", valid, "/src/a/a.go", 123 - linebase, 3},
-		{"/*line :x:1*/", valid, ":x", 1 - linebase, 0},
-		{"/*line foo ::1*/", valid, "foo :", 1 - linebase, 0},
-		{"/*line foo:123abc:1*/", valid, "foo:123abc", 1 - linebase, 0},
-		{"/*line foo :123:10*/", valid, "foo ", 123 - linebase, 10 - colbase},
-		{"/*line ::123*/", valid, ":", 123 - linebase, 0},
+		{"/*line foo:123*/   foo", valid, "foo", 123, 0},
+		{"/*line foo:123*/\n//line bar:345\nfoo", valid, "bar", 345, 0},
+		{"/*line C:foo:123*/", valid, "C:foo", 123, 0},
+		{"/*line /src/a/a.go:123*/   foo", valid, "/src/a/a.go", 123, 0},
+		{"/*line :x:1*/", valid, ":x", 1, 0},
+		{"/*line foo ::1*/", valid, "foo :", 1, 0},
+		{"/*line foo:123abc:1*/", valid, "foo:123abc", 1, 0},
+		{"/*line foo :123:10*/", valid, "foo ", 123, 10},
+		{"/*line ::123*/", valid, ":", 123, 0},
 
 		// effect of valid /*line directives on columns
-		{"/*line :x:1:10*/", valid, ":x", 1 - linebase, 10 - colbase},
-		{"/*line foo ::1:2*/", valid, "foo :", 1 - linebase, 2 - colbase},
-		{"/*line foo:123abc:1:1000*/", valid, "foo:123abc", 1 - linebase, 1000 - colbase},
-		{"/*line foo :123:1000*/\n", valid, "foo ", 124 - linebase, 0},
-		{"/*line ::123:1234*/", valid, ":", 123 - linebase, 1234 - colbase},
+		{"/*line :x:1:10*/", valid, ":x", 1, 10},
+		{"/*line foo ::1:2*/", valid, "foo :", 1, 2},
+		{"/*line foo:123abc:1:1000*/", valid, "foo:123abc", 1, 1000},
+		{"/*line foo :123:1000*/\n", valid, "foo ", 124, 1},
+		{"/*line ::123:1234*/", valid, ":", 123, 1234},
 
 		// /*line directives with omitted filenames lead to the previously used filenames
-		{"/*line :10*/", valid, "", 10 - linebase, 0},
-		{"/*line :10:20*/", valid, filename, 10 - linebase, 20 - colbase},
-		{"//line bar:1\n/*line :10*/", valid, "", 10 - linebase, 0},
-		{"//line bar:1\n/*line :10:20*/", valid, "bar", 10 - linebase, 20 - colbase},
+		{"/*line :10*/", valid, "", 10, 0},
+		{"/*line :10:20*/", valid, filename, 10, 20},
+		{"//line bar:1\n/*line :10*/", valid, "", 10, 0},
+		{"//line bar:1\n/*line :10:20*/", valid, "bar", 10, 20},
 	} {
 		base := NewFileBase(filename)
 		_, err := Parse(base, strings.NewReader(test.src), nil, nil, 0)
@@ -320,11 +320,11 @@ func TestLineDirectives(t *testing.T) {
 		if filename := pos.RelFilename(); filename != test.filename {
 			t.Errorf("%s: got filename = %q; want %q", test.src, filename, test.filename)
 		}
-		if line := pos.RelLine(); line != test.line+linebase {
-			t.Errorf("%s: got line = %d; want %d", test.src, line, test.line+linebase)
+		if line := pos.RelLine(); line != test.line {
+			t.Errorf("%s: got line = %d; want %d", test.src, line, test.line)
 		}
-		if col := pos.RelCol(); col != test.col+colbase {
-			t.Errorf("%s: got col = %d; want %d", test.src, col, test.col+colbase)
+		if col := pos.RelCol(); col != test.col {
+			t.Errorf("%s: got col = %d; want %d", test.src, col, test.col)
 		}
 	}
 }