fix(gnovm): source location always precise with line and column (#2362)

The column number was not stored in the GnoVM location. A `Nonce` field
was used to distinguished 2 block nodes on the same line. This was
applied only to block nodes, not expressions or statements.

As a result, the node location was the same for all expressions and
statements located at the same source line. This change ensures the
uniqueness of location for all nodes, in addition to providing an
accurate position in source code.

We replace `Nonce` by `Column`, computed by the Go tokenizer (the same
as line numbers). Column is always included in all AST nodes, and the
location string has a uniform format.

With this change it is now possible for the debugger to step in infinite
loops on one line like:

`for { i++; println(i) }`

This change is also necessary for a correct accounting for code
coverage, and also may be gas accounting.

Note: as `Nonce` is renamed to `Column` in protocol definitions (type
and index unchanged),
it may qualify as a BREAKING CHANGE, but I'm not completely sure of
that.
<!-- please provide a detailed description of the changes made in this
pull request. -->

<details><summary>Contributors' checklist...</summary>

- [*] Added new tests, or not needed, or not feasible
- [*] Provided an example (e.g. screenshot) to aid review or the PR is
self-explanatory
- [*] Updated the official documentation or not needed
- [*] No breaking changes were made, or a `BREAKING CHANGE: xxx` message
was included in the description
- [ ] Added references to related issues and PRs
- [*] Provided any useful hints for running manual tests
- [ ] Added new benchmarks to [generated
graphs](https://gnoland.github.io/benchmarks), if any. More info
[here](https://github.com/gnolang/gno/blob/master/.benchmarks/README.md).
</details>

examples/gno.land/p/demo/avl/z_0_filetest.gno

@@ -228,9 +228,9 @@ func main() {
 //         "@type": "/gno.RefNode",
 //         "BlockNode": null,
 //         "Location": {
+//             "Column": "0",
 //             "File": "",
 //             "Line": "0",
-//             "Nonce": "0",
 //             "PkgPath": "gno.land/r/test"
 //         }
 //     },
@@ -258,9 +258,9 @@ func main() {
 //                     "@type": "/gno.RefNode",
 //                     "BlockNode": null,
 //                     "Location": {
+//                         "Column": "1",
 //                         "File": "main.gno",
 //                         "Line": "10",
-//                         "Nonce": "0",
 //                         "PkgPath": "gno.land/r/test"
 //                     }
 //                 },
@@ -294,9 +294,9 @@ func main() {
 //                     "@type": "/gno.RefNode",
 //                     "BlockNode": null,
 //                     "Location": {
+//                         "Column": "1",
 //                         "File": "main.gno",
 //                         "Line": "15",
-//                         "Nonce": "0",
 //                         "PkgPath": "gno.land/r/test"
 //                     }
 //                 },

examples/gno.land/p/demo/avl/z_1_filetest.gno

@@ -301,9 +301,9 @@ func main() {
 //         "@type": "/gno.RefNode",
 //         "BlockNode": null,
 //         "Location": {
+//             "Column": "0",
 //             "File": "",
 //             "Line": "0",
-//             "Nonce": "0",
 //             "PkgPath": "gno.land/r/test"
 //         }
 //     },
@@ -331,9 +331,9 @@ func main() {
 //                     "@type": "/gno.RefNode",
 //                     "BlockNode": null,
 //                     "Location": {
+//                         "Column": "1",
 //                         "File": "main.gno",
 //                         "Line": "10",
-//                         "Nonce": "0",
 //                         "PkgPath": "gno.land/r/test"
 //                     }
 //                 },
@@ -367,9 +367,9 @@ func main() {
 //                     "@type": "/gno.RefNode",
 //                     "BlockNode": null,
 //                     "Location": {
+//                         "Column": "1",
 //                         "File": "main.gno",
 //                         "Line": "15",
-//                         "Nonce": "0",
 //                         "PkgPath": "gno.land/r/test"
 //                     }
 //                 },

gno.land/pkg/sdk/vm/gas_test.go

@@ -67,7 +67,7 @@ func TestAddPkgDeliverTx(t *testing.T) {
 	gasDeliver := gctx.GasMeter().GasConsumed()
 
 	assert.True(t, res.IsOK())
-	assert.Equal(t, int64(87809), gasDeliver)
+	assert.Equal(t, int64(87929), gasDeliver)
 }
 
 // Enough gas for a failed transaction.

gnovm/cmd/gno/testdata/gno_test/realm_correct.txtar

@@ -32,9 +32,9 @@ func main() {
 //         "@type": "/gno.RefNode",
 //         "BlockNode": null,
 //         "Location": {
+//             "Column": "0",
 //             "File": "",
 //             "Line": "0",
-//             "Nonce": "0",
 //             "PkgPath": "gno.land/r/x"
 //         }
 //     },
@@ -62,9 +62,9 @@ func main() {
 //                     "@type": "/gno.RefNode",
 //                     "BlockNode": null,
 //                     "Location": {
+//                         "Column": "1",
 //                         "File": "main.gno",
 //                         "Line": "6",
-//                         "Nonce": "0",
 //                         "PkgPath": "gno.land/r/x"
 //                     }
 //                 },

gnovm/cmd/gno/testdata/gno_test/realm_sync.txtar

@@ -47,9 +47,9 @@ func main() {
 //         "@type": "/gno.RefNode",
 //         "BlockNode": null,
 //         "Location": {
+//             "Column": "0",
 //             "File": "",
 //             "Line": "0",
-//             "Nonce": "0",
 //             "PkgPath": "gno.land/r/x"
 //         }
 //     },
@@ -77,9 +77,9 @@ func main() {
 //                     "@type": "/gno.RefNode",
 //                     "BlockNode": null,
 //                     "Location": {
+//                         "Column": "1",
 //                         "File": "main.gno",
 //                         "Line": "6",
-//                         "Nonce": "0",
 //                         "PkgPath": "gno.land/r/x"
 //                     }
 //                 },

gnovm/cmd/gno/testdata/gno_test/test_with-native-fallback.txtar

@@ -4,7 +4,7 @@
 
 ! stdout .+
 stderr 'panic: unknown import path net \[recovered\]'
-stderr '	panic: gno.land/r/\w{8}/contract.gno:3: unknown import path net'
+stderr '	panic: gno.land/r/\w{8}/contract.gno:3:8: unknown import path net'
 
 gno test -v --with-native-fallback .
 

gnovm/cmd/gno/testdata/gno_test/unknow_lib.txtar

@@ -4,13 +4,13 @@
 
 ! stdout .+
 stderr 'panic: unknown import path foobarbaz \[recovered\]'
-stderr '	panic: gno.land/r/\w{8}/contract.gno:3: unknown import path foobarbaz'
+stderr '	panic: gno.land/r/\w{8}/contract.gno:3:8: unknown import path foobarbaz'
 
 ! gno test -v --with-native-fallback .
 
 ! stdout .+
 stderr 'panic: unknown import path foobarbaz \[recovered\]'
-stderr '	panic: gno.land/r/\w{8}/contract.gno:3: unknown import path foobarbaz'
+stderr '	panic: gno.land/r/\w{8}/contract.gno:3:8: unknown import path foobarbaz'
 
 -- contract.gno --
 package contract

gnovm/gno.proto

@@ -140,7 +140,7 @@ message Location {
 	string PkgPath = 1;
 	string File = 2;
 	sint64 Line = 3;
-	sint64 Nonce = 4;
+	sint64 Column = 4;
 }
 
 message Attributes {
@@ -600,4 +600,4 @@ message tupleType {
 
 message RefType {
 	string ID = 1;
-}
+}

gnovm/pkg/gnolang/debugger.go

@@ -132,13 +132,11 @@ loop:
 					continue loop
 				}
 			default:
-				for _, b := range m.Debugger.breakpoints {
-					if b == m.Debugger.loc && m.Debugger.loc != m.Debugger.prevLoc {
-						m.Debugger.state = DebugAtCmd
-						m.Debugger.prevLoc = m.Debugger.loc
-						debugList(m, "")
-						continue loop
-					}
+				if atBreak(m) {
+					m.Debugger.state = DebugAtCmd
+					m.Debugger.prevLoc = m.Debugger.loc
+					debugList(m, "")
+					continue loop
 				}
 			}
 			break loop
@@ -159,6 +157,20 @@ loop:
 	}
 }
 
+// atBreak returns true if current machine location matches a breakpoint, false otherwise.
+func atBreak(m *Machine) bool {
+	loc := m.Debugger.loc
+	if loc == m.Debugger.prevLoc {
+		return false
+	}
+	for _, b := range m.Debugger.breakpoints {
+		if loc.File == b.File && loc.Line == b.Line {
+			return true
+		}
+	}
+	return false
+}
+
 // debugCmd processes a debugger REPL command. It displays a prompt, then
 // reads and parses a command from the debugger input stream, then executes
 // the corresponding function or returns an error.
@@ -231,6 +243,7 @@ func debugUpdateLocation(m *Machine) {
 		expr := m.Exprs[i]
 		if l := expr.GetLine(); l > 0 {
 			m.Debugger.loc.Line = l
+			m.Debugger.loc.Column = expr.GetColumn()
 			return
 		}
 	}
@@ -239,6 +252,7 @@ func debugUpdateLocation(m *Machine) {
 		if stmt := m.PeekStmt1(); stmt != nil {
 			if l := stmt.GetLine(); l > 0 {
 				m.Debugger.loc.Line = l
+				m.Debugger.loc.Column = stmt.GetColumn()
 				return
 			}
 		}

gnovm/pkg/gnolang/debugger_test.go

@@ -147,7 +147,7 @@ func TestDebug(t *testing.T) {
 		{in: "b 37\nc\np b\n", out: "(3 int)"},
 		{in: "b 27\nc\np b\n", out: `("!zero" string)`},
 		{in: "b 22\nc\np t.A[3]\n", out: "Command failed: slice index out of bounds: 3 (len=3)"},
-		{in: "b 43\nc\nc\np i\nd\n", out: "(1 int)"},
+		{in: "b 43\nc\nc\nc\np i\ndetach\n", out: "(1 int)"},
 	})
 
 	runDebugTest(t, "../../tests/files/a1.gno", []dtest{

gnovm/pkg/gnolang/gnolang.proto

@@ -142,7 +142,7 @@ message Location {
 	string pkg_path = 1 [json_name = "PkgPath"];
 	string file = 2 [json_name = "File"];
 	sint64 line = 3 [json_name = "Line"];
-	sint64 nonce = 4 [json_name = "Nonce"];
+	sint64 column = 4 [json_name = "Column"];
 }
 
 message Attributes {
@@ -602,4 +602,4 @@ message tupleType {
 
 message RefType {
 	string id = 1 [json_name = "ID"];
-}
+}

gnovm/pkg/gnolang/go2gno.go

@@ -137,6 +137,7 @@ func ParseFile(filename string, body string) (fn *FileNode, err error) {
 func setLoc(fs *token.FileSet, pos token.Pos, n Node) Node {
 	posn := fs.Position(pos)
 	n.SetLine(posn.Line)
+	n.SetColumn(posn.Column)
 	return n
 }
 

gnovm/pkg/gnolang/machine.go

@@ -448,11 +448,13 @@ func (m *Machine) injectLocOnPanic() {
 		// Show last location information.
 		// First, determine the line number of expression or statement if any.
 		lastLine := 0
+		lastColumn := 0
 		if len(m.Exprs) > 0 {
 			for i := len(m.Exprs) - 1; i >= 0; i-- {
 				expr := m.Exprs[i]
 				if expr.GetLine() > 0 {
 					lastLine = expr.GetLine()
+					lastColumn = expr.GetColumn()
 					break
 				}
 			}
@@ -462,6 +464,7 @@ func (m *Machine) injectLocOnPanic() {
 				stmt := m.Stmts[i]
 				if stmt.GetLine() > 0 {
 					lastLine = stmt.GetLine()
+					lastColumn = stmt.GetColumn()
 					break
 				}
 			}
@@ -476,6 +479,7 @@ func (m *Machine) injectLocOnPanic() {
 				lastLoc = loc
 				if lastLine > 0 {
 					lastLoc.Line = lastLine
+					lastLoc.Column = lastColumn
 				}
 				break
 			}

gnovm/pkg/gnolang/nodes.go

@@ -118,31 +118,23 @@ type Location struct {
 	PkgPath string
 	File    string
 	Line    int
-	Nonce   int
+	Column  int
 }
 
 func (loc Location) String() string {
-	if loc.Nonce == 0 {
-		return fmt.Sprintf("%s/%s:%d",
-			loc.PkgPath,
-			loc.File,
-			loc.Line,
-		)
-	} else {
-		return fmt.Sprintf("%s/%s:%d#%d",
-			loc.PkgPath,
-			loc.File,
-			loc.Line,
-			loc.Nonce,
-		)
-	}
+	return fmt.Sprintf("%s/%s:%d:%d",
+		loc.PkgPath,
+		loc.File,
+		loc.Line,
+		loc.Column,
+	)
 }
 
 func (loc Location) IsZero() bool {
 	return loc.PkgPath == "" &&
 		loc.File == "" &&
 		loc.Line == 0 &&
-		loc.Nonce == 0
+		loc.Column == 0
 }
 
 // ----------------------------------------
@@ -153,9 +145,10 @@ func (loc Location) IsZero() bool {
 // for preprocessing) are stored in .data.
 
 type Attributes struct {
-	Line  int
-	Label Name
-	data  map[interface{}]interface{} // not persisted
+	Line   int
+	Column int
+	Label  Name
+	data   map[interface{}]interface{} // not persisted
 }
 
 func (attr *Attributes) GetLine() int {
@@ -166,6 +159,14 @@ func (attr *Attributes) SetLine(line int) {
 	attr.Line = line
 }
 
+func (attr *Attributes) GetColumn() int {
+	return attr.Column
+}
+
+func (attr *Attributes) SetColumn(column int) {
+	attr.Column = column
+}
+
 func (attr *Attributes) GetLabel() Name {
 	return attr.Label
 }
@@ -199,6 +200,8 @@ type Node interface {
 	Copy() Node
 	GetLine() int
 	SetLine(int)
+	GetColumn() int
+	SetColumn(int)
 	GetLabel() Name
 	SetLabel(Name)
 	HasAttribute(key interface{}) bool