Merge pull request #3578 from onflow/supun/improve-parser-errors

Always return parser errors gracefully

runtime/environment.go

@@ -522,9 +522,15 @@ func (e *interpreterEnvironment) parseAndCheckProgram(
 	err error,
 ) {
 	wrapParsingCheckingError := func(err error) error {
-		return &ParsingCheckingError{
-			Err:      err,
-			Location: location,
+		switch err.(type) {
+		// Wrap only parsing and checking errors.
+		case *sema.CheckerError, parser.Error:
+			return &ParsingCheckingError{
+				Err:      err,
+				Location: location,
+			}
+		default:
+			return err
 		}
 	}
 

runtime/error_test.go

@@ -59,6 +59,7 @@ func TestRuntimeError(t *testing.T) {
 				Location:  location,
 			},
 		)
+
 		require.EqualError(
 			t,
 			err,

runtime/old_parser/parser.go

@@ -91,8 +91,13 @@ func Parse[T any](
 	config Config,
 ) (result T, errors []error) {
 	// create a lexer, which turns the input string into tokens
-	tokens := lexer.Lex(input, memoryGauge)
+	tokens, err := lexer.Lex(input, memoryGauge)
+	if err != nil {
+		errors = append(errors, err)
+		return
+	}
 	defer tokens.Reclaim()
+
 	return ParseTokenStream(
 		memoryGauge,
 		tokens,
@@ -637,8 +642,12 @@ func ParseArgumentList(
 }
 
 func ParseProgram(memoryGauge common.MemoryGauge, code []byte, config Config) (program *ast.Program, err error) {
-	tokens := lexer.Lex(code, memoryGauge)
+	tokens, err := lexer.Lex(code, memoryGauge)
+	if err != nil {
+		return
+	}
 	defer tokens.Reclaim()
+
 	return ParseProgramFromTokenStream(memoryGauge, tokens, config)
 }
 

runtime/old_parser/parser_test.go

@@ -732,18 +732,11 @@ func TestParseArgumentList(t *testing.T) {
 		gauge := makeLimitingMemoryGauge()
 		gauge.Limit(common.MemoryKindTypeToken, 0)
 
-		var panicMsg any
-		(func() {
-			defer func() {
-				panicMsg = recover()
-			}()
+		_, err := ParseArgumentList(gauge, []byte(`(1, b: true)`), Config{})
+		require.Len(t, err, 1)
+		require.IsType(t, errors.MemoryError{}, err[0])
 
-			ParseArgumentList(gauge, []byte(`(1, b: true)`), Config{})
-		})()
-
-		require.IsType(t, errors.MemoryError{}, panicMsg)
-
-		fatalError, _ := panicMsg.(errors.MemoryError)
+		fatalError, _ := err[0].(errors.MemoryError)
 		var expectedError limitingMemoryGaugeError
 		assert.ErrorAs(t, fatalError, &expectedError)
 	})

runtime/parser/expression_test.go

@@ -324,17 +324,11 @@ func TestParseAdvancedExpression(t *testing.T) {
 		gauge.debug = true
 		gauge.Limit(common.MemoryKindPosition, 11)
 
-		var panicMsg any
-		(func() {
-			defer func() {
-				panicMsg = recover()
-			}()
-			ParseExpression(gauge, []byte("1 < 2"), Config{})
-		})()
+		_, errs := ParseExpression(gauge, []byte("1 < 2"), Config{})
+		require.Len(t, errs, 1)
+		require.IsType(t, errors.MemoryError{}, errs[0])
 
-		require.IsType(t, errors.MemoryError{}, panicMsg)
-
-		fatalError, _ := panicMsg.(errors.MemoryError)
+		fatalError, _ := errs[0].(errors.MemoryError)
 		var expectedError limitingMemoryGaugeError
 		assert.ErrorAs(t, fatalError, &expectedError)
 	})
@@ -346,18 +340,11 @@ func TestParseAdvancedExpression(t *testing.T) {
 		gauge := makeLimitingMemoryGauge()
 		gauge.Limit(common.MemoryKindIntegerExpression, 1)
 
-		var panicMsg any
-		(func() {
-			defer func() {
-				panicMsg = recover()
-			}()
-
-			ParseExpression(gauge, []byte("1 < 2 > 3"), Config{})
-		})()
-
-		require.IsType(t, errors.MemoryError{}, panicMsg)
+		_, errs := ParseExpression(gauge, []byte("1 < 2 > 3"), Config{})
+		require.Len(t, errs, 1)
+		require.IsType(t, errors.MemoryError{}, errs[0])
 
-		fatalError, _ := panicMsg.(errors.MemoryError)
+		fatalError, _ := errs[0].(errors.MemoryError)
 		var expectedError limitingMemoryGaugeError
 		assert.ErrorAs(t, fatalError, &expectedError)
 	})

runtime/parser/lexer/lexer.go

@@ -144,13 +144,13 @@ var pool = sync.Pool{
 	},
 }
 
-func Lex(input []byte, memoryGauge common.MemoryGauge) TokenStream {
+func Lex(input []byte, memoryGauge common.MemoryGauge) (TokenStream, error) {
 	l := pool.Get().(*lexer)
 	l.clear()
 	l.memoryGauge = memoryGauge
 	l.input = input
-	l.run(rootState)
-	return l
+	err := l.run(rootState)
+	return l, err
 }
 
 // run executes the stateFn, which will scan the runes in the input
@@ -162,32 +162,29 @@ func Lex(input []byte, memoryGauge common.MemoryGauge) TokenStream {
 // stateFn is returned, which for example happens when reaching the end of the file.
 //
 // When all stateFn have been executed, an EOF token is emitted.
-func (l *lexer) run(state stateFn) {
+func (l *lexer) run(state stateFn) (err error) {
 
 	// catch panic exceptions, emit it to the tokens channel before
 	// closing it
 	defer func() {
 		if r := recover(); r != nil {
-			var err error
 			switch r := r.(type) {
-			case errors.MemoryError, errors.InternalError:
-				// fatal errors and internal errors percolates up.
-				// Note: not all fatal errors are internal errors.
-				// e.g: memory limit exceeding is a fatal error, but also a user error.
-				panic(r)
+			// fatal errors and internal errors percolates up.
+			// Note: not all fatal errors are internal errors.
+			// e.g: memory limit exceeding is a fatal error, but also a user error.
 			case error:
 				err = r
 			default:
 				err = fmt.Errorf("lexer: %v", r)
 			}
-
-			l.emitError(err)
 		}
 	}()
 
 	for state != nil {
 		state = state(l)
 	}
+
+	return
 }
 
 // next decodes the next rune (UTF8 character) from the input string.

runtime/parser/lexer/lexer_test.go

@@ -63,7 +63,10 @@ func testLex(t *testing.T, input string, expected []token) {
 
 	bytes := []byte(input)
 
-	withTokens(Lex(bytes, nil), func(actualTokens []Token) {
+	tokenStream, err := Lex(bytes, nil)
+	require.NoError(t, err)
+
+	withTokens(tokenStream, func(actualTokens []Token) {
 		utils.AssertEqualWithDiff(t, expectedTokens, actualTokens)
 
 		require.Len(t, actualTokens, len(expectedTokens))
@@ -2385,7 +2388,8 @@ func TestRevert(t *testing.T) {
 
 	t.Parallel()
 
-	tokenStream := Lex([]byte("1 2 3"), nil)
+	tokenStream, err := Lex([]byte("1 2 3"), nil)
+	require.NoError(t, err)
 
 	// Assert all tokens
 
@@ -2550,7 +2554,8 @@ func TestEOFsAfterError(t *testing.T) {
 
 	t.Parallel()
 
-	tokenStream := Lex([]byte(`1 ''`), nil)
+	tokenStream, err := Lex([]byte(`1 ''`), nil)
+	require.NoError(t, err)
 
 	// Assert all tokens
 
@@ -2613,7 +2618,8 @@ func TestEOFsAfterEmptyInput(t *testing.T) {
 
 	t.Parallel()
 
-	tokenStream := Lex(nil, nil)
+	tokenStream, err := Lex(nil, nil)
+	require.NoError(t, err)
 
 	// Assert EOFs keep on being returned for Next()
 	// at the end of the stream
@@ -2644,10 +2650,6 @@ func TestLimit(t *testing.T) {
 
 	code := b.String()
 
-	assert.PanicsWithValue(t,
-		TokenLimitReachedError{},
-		func() {
-			_ = Lex([]byte(code), nil)
-		},
-	)
+	_, err := Lex([]byte(code), nil)
+	require.ErrorAs(t, err, &TokenLimitReachedError{})
 }

runtime/parser/parser.go

@@ -100,8 +100,13 @@ func Parse[T any](
 	config Config,
 ) (result T, errors []error) {
 	// create a lexer, which turns the input string into tokens
-	tokens := lexer.Lex(input, memoryGauge)
+	tokens, err := lexer.Lex(input, memoryGauge)
+	if err != nil {
+		errors = append(errors, err)
+		return
+	}
 	defer tokens.Reclaim()
+
 	return ParseTokenStream(
 		memoryGauge,
 		tokens,
@@ -127,29 +132,34 @@ func ParseTokenStream[T any](
 
 	defer func() {
 		if r := recover(); r != nil {
+			var err error
 			switch r := r.(type) {
 			case ParseError:
 				// Report parser errors.
 				p.report(r)
 
 			// Do not treat non-parser errors as syntax errors.
-			case errors.InternalError, errors.UserError:
-				// Also do not wrap non-parser errors, that are already
-				// known cadence errors. i.e: internal errors / user errors.
-				// e.g: `errors.MemoryError`
-				panic(r)
+			// Also do not wrap non-parser errors, that are already
+			// known cadence errors. i.e: internal errors / user errors.
+			// e.g: `errors.MemoryError`
+			case errors.UserError:
+				err = r
+			case errors.InternalError:
+				err = r
 			case error:
 				// Any other error/panic is an internal error.
 				// Thus, wrap with an UnexpectedError to mark it as an internal error
 				// and propagate up the call stack.
-				panic(errors.NewUnexpectedErrorFromCause(r))
+				err = errors.NewUnexpectedErrorFromCause(r)
 			default:
-				panic(errors.NewUnexpectedError("parser: %v", r))
+				err = errors.NewUnexpectedError("parser: %v", r)
 			}
 
 			var zero T
 			result = zero
 			errs = p.errors
+
+			errs = append(errs, err)
 		}
 
 		for _, bufferedErrors := range p.bufferedErrorsStack {
@@ -677,8 +687,12 @@ func ParseArgumentList(
 }
 
 func ParseProgram(memoryGauge common.MemoryGauge, code []byte, config Config) (program *ast.Program, err error) {
-	tokens := lexer.Lex(code, memoryGauge)
+	tokens, err := lexer.Lex(code, memoryGauge)
+	if err != nil {
+		return
+	}
 	defer tokens.Reclaim()
+
 	return ParseProgramFromTokenStream(memoryGauge, tokens, config)
 }
 

runtime/parser/parser_test.go

@@ -734,18 +734,12 @@ func TestParseArgumentList(t *testing.T) {
 		gauge := makeLimitingMemoryGauge()
 		gauge.Limit(common.MemoryKindTypeToken, 0)
 
-		var panicMsg any
-		(func() {
-			defer func() {
-				panicMsg = recover()
-			}()
+		_, errs := ParseArgumentList(gauge, []byte(`(1, b: true)`), Config{})
+		require.Len(t, errs, 1)
 
-			ParseArgumentList(gauge, []byte(`(1, b: true)`), Config{})
-		})()
+		require.IsType(t, errors.MemoryError{}, errs[0])
 
-		require.IsType(t, errors.MemoryError{}, panicMsg)
-
-		fatalError, _ := panicMsg.(errors.MemoryError)
+		fatalError, _ := errs[0].(errors.MemoryError)
 		var expectedError limitingMemoryGaugeError
 		assert.ErrorAs(t, fatalError, &expectedError)
 	})

runtime/repl.go

@@ -254,8 +254,11 @@ func (r *REPL) Accept(code []byte, eval bool) (inputIsComplete bool, err error)
 		code = prefixedCode
 	}
 
-	tokens := lexer.Lex(code, nil)
+	tokens, err := lexer.Lex(code, nil)
 	defer tokens.Reclaim()
+	if err != nil {
+		return
+	}
 
 	inputIsComplete = isInputComplete(tokens)
 

runtime/runtime_test.go

@@ -7497,7 +7497,7 @@ func TestRuntimeInternalErrors(t *testing.T) {
 
 		RequireError(t, err)
 
-		assertRuntimeErrorIsInternalError(t, err)
+		assertRuntimeErrorIsExternalError(t, err)
 	})
 
 }