amr sarhan (amr807) · Nov 11, 2026 · Nov 12, 2026 · Nov 13, 2026
diff --git a/tsc/internal/checker/checker.go b/tsc/internal/checker/checker.go
@@ -31,6 +31,7 @@ import (
 	"github.com/microsoft/TypeScript/tsc/internal/tsoptions"
 	"github.com/microsoft/TypeScript/tsc/internal/tspath"
 	"github.com/zeebo/xxh3"
+	"unicode/utf8"
 )
 
 // CheckMode
@@ -8785,7 +8786,9 @@ func (c *Checker) resolveCallExpression(node *ast.Node, candidatesOutArray *[]*S
 			if len(node.Arguments()) == 1 {
 				text := ast.GetSourceFileOfNode(node).Text()
 				options := scanner.SkipTriviaOptions{StopAfterLineBreak: true}
-				if stringutil.IsLineBreak(rune(text[scanner.SkipTriviaEx(text, node.Expression().End(), &options)-1])) {
+				pos := scanner.SkipTriviaEx(text, node.Expression().End(), &options)
+				lineBreak, _ := utf8.DecodeLastRuneInString(text[:pos])
+				if stringutil.IsLineBreak(lineBreak) {
 					relatedInformation = createDiagnosticForNode(node.Expression(), diagnostics.Are_you_missing_a_semicolon)
 				}
 			}

diff --git a/tsc/internal/ls/change/delete.go b/tsc/internal/ls/change/delete.go
@@ -2,6 +2,7 @@ package change
 
 import (
 	"slices"
+	"unicode/utf8"
 
 	"github.com/microsoft/TypeScript/tsc/internal/ast"
 	"github.com/microsoft/TypeScript/tsc/internal/astnav"
@@ -234,12 +235,14 @@ func (t *Tracker) endPositionToDeleteNodeInList(sourceFile *ast.SourceFile, node
 		if isSeparator(prevNode, prevToken) {
 			pos := scanner.SkipTriviaEx(sourceFile.Text(), token.End(), &scanner.SkipTriviaOptions{StopAfterLineBreak: true, StopAtComments: true})
 			if positionsAreOnSameLine(astnav.GetStartOfNode(prevToken, sourceFile, false), astnav.GetStartOfNode(token, sourceFile, false), sourceFile) {
-				if pos > 0 && stringutil.IsLineBreak(rune(sourceFile.Text()[pos-1])) {
-					return pos - 1
+				lastRune, size := utf8.DecodeLastRuneInString(sourceFile.Text()[:pos])
+				if pos > 0 && stringutil.IsLineBreak(lastRune) {
+					return pos - size
 				}
 				return pos
 			}
-			if stringutil.IsLineBreak(rune(sourceFile.Text()[pos])) {
+			lineBreak, _ := utf8.DecodeRuneInString(sourceFile.Text()[pos:])
+			if stringutil.IsLineBreak(lineBreak) {
 				return pos
 			}
 		}

diff --git a/tsc/internal/ls/change/tracker.go b/tsc/internal/ls/change/tracker.go
@@ -3,6 +3,7 @@ package change
 import (
 	"context"
 	"slices"
+	"unicode/utf8"
 
 	"github.com/microsoft/TypeScript/tsc/internal/ast"
 	"github.com/microsoft/TypeScript/tsc/internal/astnav"
@@ -498,9 +499,13 @@ func (t *Tracker) InsertNodeInListAfter(sourceFile *ast.SourceFile, after *ast.N
 		indentation := format.FindFirstNonWhitespaceColumn(afterStartLinePosition, afterStart, sourceFile, t.formatSettings)
 		// insert element before the line break on the line that contains 'after' element
 		insertPos := scanner.SkipTriviaEx(sourceFile.Text(), end, &scanner.SkipTriviaOptions{StopAfterLineBreak: true, StopAtComments: false})
-		// find position before "\n" or "\r\n"
-		for insertPos != end && stringutil.IsLineBreak(rune(sourceFile.Text()[insertPos-1])) {
-			insertPos--
+		// find position before the line break
+		for insertPos != end {
+			lastRune, size := utf8.DecodeLastRuneInString(sourceFile.Text()[end:insertPos])
+			if !stringutil.IsLineBreak(lastRune) {
+				break
+			}
+			insertPos -= size
 		}
 		insertLSPos := core.TextPos(insertPos)
 		t.ReplaceRange(

diff --git a/tsc/internal/ls/change/trackerimpl.go b/tsc/internal/ls/change/trackerimpl.go
@@ -5,6 +5,7 @@ import (
 	"slices"
 	"strings"
 	"unicode"
+	"unicode/utf8"
 
 	"github.com/microsoft/TypeScript/tsc/internal/ast"
 	"github.com/microsoft/TypeScript/tsc/internal/astnav"
@@ -394,7 +395,8 @@ func (t *Tracker) getAdjustedEndPosition(sourceFile *ast.SourceFile, node *ast.N
 
 	newEnd := scanner.SkipTriviaEx(sourceFile.Text(), node.End(), &scanner.SkipTriviaOptions{StopAfterLineBreak: true})
 
-	if newEnd != node.End() && (TrailingTriviaOption == TrailingTriviaOptionInclude || stringutil.IsLineBreak(rune(sourceFile.Text()[newEnd-1]))) {
+	lastRune, _ := utf8.DecodeLastRuneInString(sourceFile.Text()[:newEnd])
+	if newEnd != node.End() && (TrailingTriviaOption == TrailingTriviaOptionInclude || stringutil.IsLineBreak(lastRune)) {
 		return newEnd
 	}
 	return node.End()

diff --git a/tsc/internal/ls/change/trackerimpl_test.go b/tsc/internal/ls/change/trackerimpl_test.go
@@ -1,9 +1,14 @@
 package change
 
 import (
-	"testing"
-
+	"context"
+	"github.com/microsoft/TypeScript/tsc/internal/ast"
+	"github.com/microsoft/TypeScript/tsc/internal/core"
+	"github.com/microsoft/TypeScript/tsc/internal/ls/lsutil"
 	"github.com/microsoft/TypeScript/tsc/internal/lsp/lsproto"
+	"github.com/microsoft/TypeScript/tsc/internal/parser"
+	"strings"
+	"testing"
 )
 
 func TestTextEditsConflictAtSameInsertionPointAcrossProjections(t *testing.T) {
@@ -20,3 +25,76 @@ func TestTextEditsConflictAtSameInsertionPointAcrossProjections(t *testing.T) {
 		t.Fatal("insertions at the same position within one projection should retain their existing ordering")
 	}
 }
+func TestInsertNodeInListAfterUnicodeLineSeparators(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name      string
+		separator string
+	}{
+		{name: "U+2028", separator: "\u2028"},
+		{name: "U+2029", separator: "\u2029"},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+
+			text := "const values = [\n    1,\n    2  " + test.separator + "];"
+
+			sourceFile := parser.ParseSourceFile(ast.SourceFileParseOptions{
+				FileName: "/index.ts",
+				PathKey:  "/index.ts",
+			}, text, core.ScriptKindTS)
+
+			declaration := sourceFile.Statements.Nodes[0].
+				AsVariableStatement().
+				DeclarationList.
+				AsVariableDeclarationList().
+				Declarations.Nodes[0]
+
+			array := declaration.AsVariableDeclaration().Initializer
+			elements := array.AsArrayLiteralExpression().Elements.Nodes
+			after := elements[1]
+
+			tracker := NewTracker(
+				context.Background(),
+				core.EmptyCompilerOptions,
+				lsutil.GetDefaultFormatCodeSettings(),
+				nil,
+			)
+
+			newNode := tracker.NewNumericLiteral("3", ast.TokenFlagsNone)
+
+			tracker.InsertNodeInListAfter(
+				sourceFile,
+				after,
+				newNode,
+				array.AsArrayLiteralExpression().Elements,
+			)
+
+			expectedPosition := strings.Index(text, test.separator)
+			found := false
+
+			for _, edit := range tracker.changes.Get(sourceFile) {
+				if edit.Node == newNode {
+					found = true
+					actualPosition := edit.TextRange.Pos()
+
+					if actualPosition != expectedPosition {
+						t.Fatalf(
+							"insertion position = %d, want %d",
+							actualPosition,
+							expectedPosition,
+						)
+					}
+					break
+				}
+			}
+
+			if !found {
+				t.Fatal("could not find the edit inserting the new node")
+			}
+		})
+	}
+}
diff --git a/tsc/internal/scanner/scanner.go b/tsc/internal/scanner/scanner.go
@@ -2388,6 +2388,13 @@ func SkipTriviaEx(text string, pos int, options *SkipTriviaOptions) int {
 			}
 			canConsumeStar = options.InJSDoc
 			continue
+		case '\u2028', '\u2029':
+			pos += size
+			if options.StopAfterLineBreak {
+				return pos
+			}
+			canConsumeStar = options.InJSDoc
+			continue
 		case '\t', '\v', '\f', ' ':
 			pos++
 			continue

diff --git a/tsc/internal/scanner/scanner_test.go b/tsc/internal/scanner/scanner_test.go
@@ -173,3 +173,73 @@ func TestRegExpLiteralReplacementCharacterInClassRange(t *testing.T) {
 		})
 	}
 }
+
+func TestSkipTriviaExHandlesUnicodeLineSeparators(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name               string
+		text               string
+		stopAfterLineBreak bool
+		expected           int
+	}{
+		{
+			name:               "U+2028 stops after line separator",
+			text:               " \u2028  next",
+			stopAfterLineBreak: true,
+			expected:           len(" \u2028"),
+		},
+		{
+			name:               "U+2029 stops after paragraph separator",
+			text:               " \u2029  next",
+			stopAfterLineBreak: true,
+			expected:           len(" \u2029"),
+		},
+		{
+			name:     "U+2028 continues when not stopping",
+			text:     " \u2028  next",
+			expected: len(" \u2028  "),
+		},
+		{
+			name:     "U+2029 continues when not stopping",
+			text:     " \u2029  next",
+			expected: len(" \u2029  "),
+		},
+		{
+			name:               "LF preserves existing behavior",
+			text:               " \n  next",
+			stopAfterLineBreak: true,
+			expected:           len(" \n"),
+		},
+		{
+			name:               "CRLF preserves existing behavior",
+			text:               " \r\n  next",
+			stopAfterLineBreak: true,
+			expected:           len(" \r\n"),
+		},
+		{
+			name:               "line comment stops at U+2028",
+			text:               "// comment\u2028  next",
+			stopAfterLineBreak: true,
+			expected:           len("// comment\u2028"),
+		},
+		{
+			name:     "line comment continues after U+2029",
+			text:     "// comment\u2029  next",
+			expected: len("// comment\u2029  "),
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+
+			options := &SkipTriviaOptions{
+				StopAfterLineBreak: test.stopAfterLineBreak,
+			}
+
+			actual := SkipTriviaEx(test.text, 0, options)
+			assert.Equal(t, actual, test.expected)
+		})
+	}
+}
diff --git a/tsc/testdata/baselines/reference/compiler/betterErrorForAccidentalCall.errors.txt b/tsc/testdata/baselines/reference/compiler/betterErrorForAccidentalCall.errors.txt
@@ -8,9 +8,13 @@ betterErrorForAccidentalCall.ts(10,1): error TS2349: This expression is not call
   Type 'String' has no call signatures.
 betterErrorForAccidentalCall.ts(13,1): error TS2349: This expression is not callable.
   Type 'String' has no call signatures.
+betterErrorForAccidentalCall.ts(16,1): error TS2349: This expression is not callable.
+  Type 'String' has no call signatures.
+betterErrorForAccidentalCall.ts(19,1): error TS2349: This expression is not callable.
+  Type 'String' has no call signatures.
 
 
-==== betterErrorForAccidentalCall.ts (5 errors) ====
+==== betterErrorForAccidentalCall.ts (7 errors) ====
     declare function foo(): string;
 
     foo()(1 as number).toString();
@@ -43,4 +47,16 @@ betterErrorForAccidentalCall.ts(13,1): error TS2349: This expression is not call
 !!! error TS2349:   Type 'String' has no call signatures.
 !!! related TS2734 betterErrorForAccidentalCall.ts:13:1: Are you missing a semicolon?
         (<number>1).toString();
-
+
+    foo() (1 as number).toString();
+    ~~~~~
+!!! error TS2349: This expression is not callable.
+!!! error TS2349:   Type 'String' has no call signatures.
+!!! related TS2734 betterErrorForAccidentalCall.ts:16:1: Are you missing a semicolon?
+
+    foo() (1 as number).toString();
+
+
+!!! error TS2349: This expression is not callable.
+!!! error TS2349:   Type 'String' has no call signatures.
+!!! related TS2734 betterErrorForAccidentalCall.ts:19:1: Are you missing a semicolon?
diff --git a/tsc/testdata/baselines/reference/compiler/betterErrorForAccidentalCall.js b/tsc/testdata/baselines/reference/compiler/betterErrorForAccidentalCall.js
@@ -15,6 +15,10 @@ foo()
 
 foo()
     (<number>1).toString();
+
+foo() (1 as number).toString();
+
+foo() (1 as number).toString();
 
 
 //// [betterErrorForAccidentalCall.js]
@@ -24,3 +28,5 @@ foo()(1).toString();
 foo()(1).toString();
 foo()(1 + 2).toString();
 foo()(1).toString();
+foo()(1).toString();
+foo()(1).toString();
diff --git a/tsc/testdata/baselines/reference/compiler/betterErrorForAccidentalCall.symbols b/tsc/testdata/baselines/reference/compiler/betterErrorForAccidentalCall.symbols
@@ -25,3 +25,13 @@ foo()
 
     (<number>1).toString();
 
+foo()
+>foo : Symbol(foo, Decl(betterErrorForAccidentalCall.ts, 0, 0))
+
+(1 as number).toString();
+
+foo()
+>foo : Symbol(foo, Decl(betterErrorForAccidentalCall.ts, 0, 0))
+
+(1 as number).toString();
+
diff --git a/tsc/testdata/baselines/reference/compiler/betterErrorForAccidentalCall.types b/tsc/testdata/baselines/reference/compiler/betterErrorForAccidentalCall.types
@@ -61,3 +61,27 @@ foo()
 >1 : 1
 >toString : any
 
+foo()
+>foo() (1 as number).toString() : any
+>foo() (1 as number).toString : any
+>foo() (1 as number) : any
+>foo() : string
+>foo : () => string
+
+(1 as number).toString();
+>1 as number : number
+>1 : 1
+>toString : any
+
+foo()
+>foo() (1 as number).toString() : any
+>foo() (1 as number).toString : any
+>foo() (1 as number) : any
+>foo() : string
+>foo : () => string
+
+(1 as number).toString();
+>1 as number : number
+>1 : 1
+>toString : any
+
diff --git a/tsc/testdata/tests/cases/compiler/betterErrorForAccidentalCall.ts b/tsc/testdata/tests/cases/compiler/betterErrorForAccidentalCall.ts
@@ -13,3 +13,7 @@ foo()
 
 foo()
     (<number>1).toString();
+
+foo() (1 as number).toString();
+
+foo() (1 as number).toString();