stack: add support for 1.17 stack traces (#74)

go1.17 adds "uncertainty" to the stack trace. Add support to process the trailing "?" and add Arg.IsInaccurate to represent this.

https://go.dev/doc/go1.17#compiler

stack/context.go

@@ -257,14 +257,15 @@ var (
 	// gotRaceHeader1, done
 	raceHeaderFooter = []byte("==================")
 	// gotRaceHeader2
-	raceHeader = []byte("WARNING: DATA RACE")
-	crlf       = []byte("\r\n")
-	lf         = []byte("\n")
-	commaSpace = []byte(", ")
-	writeCap   = []byte("Write")
-	writeLow   = []byte("write")
-	threeDots  = []byte("...")
-	underscore = []byte("_")
+	raceHeader             = []byte("WARNING: DATA RACE")
+	crlf                   = []byte("\r\n")
+	lf                     = []byte("\n")
+	commaSpace             = []byte(", ")
+	writeCap               = []byte("Write")
+	writeLow               = []byte("write")
+	threeDots              = []byte("...")
+	underscore             = []byte("_")
+	inaccurateQuestionMark = []byte("?")
 )
 
 // These are effectively constants.
@@ -854,13 +855,18 @@ func parseArgs(line []byte) (Args, error) {
 				arg := Arg{IsOffsetTooLarge: true}
 				cur.Values = append(cur.Values, arg)
 			default:
+				inaccurate := bytes.HasSuffix(a, inaccurateQuestionMark)
+				if inaccurate {
+					a = a[:len(a)-len(inaccurateQuestionMark)]
+				}
+
 				v, err := strconv.ParseUint(unsafeString(a), 0, 64)
 				if err != nil {
 					return Args{}, errors.New("failed to parse int")
 				}
 				// Assume the stack was generated with the same bitness (32 vs 64) as
 				// the code processing it.
-				arg := Arg{Value: v, IsPtr: v > pointerFloor && v < pointerCeiling}
+				arg := Arg{Value: v, IsPtr: v > pointerFloor && v < pointerCeiling, IsInaccurate: inaccurate}
 				cur.Values = append(cur.Values, arg)
 			}
 		}

stack/context_test.go

@@ -1057,6 +1057,56 @@ func TestScanSnapshotSynthetic(t *testing.T) {
 			},
 		},
 
+		{
+			name: "WithCarriageReturn1.18Inaccurate",
+			in: []string{
+				"goroutine 1 [running]:",
+				"github.com/cockroachdb/cockroach/storage/engine._Cfunc_DBIterSeek()",
+				" ??:0 +0x6d",
+				"gopkg.in/yaml%2ev2.handleErr(0x433b20?)",
+				"\t/gopath/src/gopkg.in/yaml.v2/yaml.go:153 +0xc6",
+				"reflect.Value.assignTo(0x570860, 0x803f3e0, 0x15)",
+				"\t/goroot/src/reflect/value.go:2125 +0x368",
+				"main.main()",
+				"\t/gopath/src/github.com/maruel/panicparse/stack/stack.go:428 +0x27",
+				"",
+			},
+			err: io.EOF,
+			want: []*Goroutine{
+				{
+					Signature: Signature{
+						State: "running",
+						Stack: Stack{
+							Calls: []Call{
+								newCall(
+									"github.com/cockroachdb/cockroach/storage/engine._Cfunc_DBIterSeek",
+									Args{},
+									"??",
+									0),
+								newCall(
+									"gopkg.in/yaml%2ev2.handleErr",
+									Args{Values: []Arg{{Value: 0x433b20, IsPtr: true, IsInaccurate: true}}},
+									"/gopath/src/gopkg.in/yaml.v2/yaml.go",
+									153),
+								newCall(
+									"reflect.Value.assignTo",
+									Args{Values: []Arg{{Value: 0x570860, IsPtr: true}, {Value: 0x803f3e0, IsPtr: true}, {Value: 0x15}}},
+									"/goroot/src/reflect/value.go",
+									2125),
+								newCall(
+									"main.main",
+									Args{},
+									"/gopath/src/github.com/maruel/panicparse/stack/stack.go",
+									428),
+							},
+						},
+					},
+					ID:    1,
+					First: true,
+				},
+			},
+		},
+
 		// goconvey is culprit of this.
 		{
 			name: "Indented",

stack/stack.go

@@ -122,6 +122,10 @@ type Arg struct {
 	// preventing the argument from being printed in the stack trace.
 	IsOffsetTooLarge bool
 
+	// IsInaccurate determines if Value is inaccurate. Stacks could have inaccurate values
+	// for arguments passed in registers. Go 1.18 prints a ? for these values.
+	IsInaccurate bool
+
 	// The following are set if IsAggregate == true.
 
 	// Fields are the fields/elements of aggregate-typed arguments.