Handle conflict markers

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/Legacy/CSharpBlockTest.cs

@@ -1082,6 +1082,136 @@ public void SwitchExpression_WithMarkupInside_WithLessThan()
             """);
     }
 
+    [Fact]
+    public void GitConflictMarker_InMarkup()
+    {
+        ParseDocumentTest("""
+            <div>
+            <<<<<<< HEAD
+            <p>Current changes</p>
+            =======
+            <p>Incoming changes</p>
+            >>>>>>> feature-branch
+            </div>
+            """);
+    }
+
+    [Fact]
+    public void GitConflictMarker_InCodeBlock()
+    {
+        ParseDocumentTest("""
+            @{
+            <<<<<<< HEAD
+                var x = 1;
+            =======
+                var x = 2;
+            >>>>>>> feature-branch
+            }
+            """);
+    }
+
+    [Fact]
+    public void GitConflictMarker_InExpression()
+    {
+        ParseDocumentTest("""
+            @(
+            <<<<<<< HEAD
+            someValue
+            =======
+            otherValue
+            >>>>>>> feature-branch
+            )
+            """);
+    }
+
+    [Fact]
+    public void GitConflictMarker_MixedWithRazor()
+    {
+        ParseDocumentTest("""
+            @if (true)
+            {
+            <<<<<<< HEAD
+                <p>@currentValue</p>
+            =======
+                <p>@incomingValue</p>
+            >>>>>>> feature-branch
+            }
+            """);
+    }
+
+    [Fact]
+    public void GitConflictMarker_StartMarkerOnly()
+    {
+        ParseDocumentTest("""
+            <div>
+            <<<<<<< HEAD
+            <p>Unresolved conflict</p>
+            </div>
+            """);
+    }
+
+    [Fact]
+    public void GitConflictMarker_WithDividerOnly()
+    {
+        ParseDocumentTest("""
+            <div>
+            <<<<<<< HEAD
+            <p>Current changes</p>
+            =======
+            <p>Missing end marker</p>
+            </div>
+            """);
+    }
+
+    [Fact]
+    public void GitConflictMarker_AtDocumentStart()
+    {
+        ParseDocumentTest("""
+            <<<<<<< HEAD
+            <p>Current</p>
+            =======
+            <p>Incoming</p>
+            >>>>>>> main
+            """);
+    }
+
+    [Fact]
+    public void GitConflictMarker_InImplicitExpression()
+    {
+        ParseDocumentTest("""
+            <p>@<<<<<<< HEAD</p>
+            """);
+    }
+
+
+    [Fact]
+    public void GitConflictMarker_Malformed_Trailing()
+    {
+        ParseDocumentTest("""
+            @{
+            <<<<<<< HEAD var x = 0;
+                var x = 1;
+            ======= var x = 3;
+                var x = 2;
+            >>>>>>> feature-branch var x = 4;
+            }
+            """);
+    }
+
+    [Fact]
+    public void GitConflictMarker_Malformed_Leading()
+    {
+        ParseDocumentTest("""
+            @{
+            var x = 0; <<<<<<< HEAD 
+                var x = 1;
+            var x = 3; ======= 
+                var x = 2;
+            var x = 4; >>>>>>> feature-branch 
+            }
+            """);
+    }
+
     private void RunRazorCommentBetweenClausesTest(string preComment, string postComment, AcceptedCharactersInternal acceptedCharacters = AcceptedCharactersInternal.Any)
     {
         ParseDocumentTest(preComment + "@* Foo *@ @* Bar *@" + postComment);

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpBlockTest/GitConflictMarker_AtDocumentStart.cspans.txt

@@ -0,0 +1,17 @@
+Markup span at (0:0,0 [1] ) - Parent: Tag block at (0:0,0 [1] )
+Markup span at (1:0,1 [1] ) - Parent: Tag block at (1:0,1 [1] )
+Markup span at (2:0,2 [1] ) - Parent: Tag block at (2:0,2 [1] )
+Markup span at (3:0,3 [1] ) - Parent: Tag block at (3:0,3 [1] )
+Markup span at (4:0,4 [1] ) - Parent: Tag block at (4:0,4 [1] )
+Markup span at (5:0,5 [1] ) - Parent: Tag block at (5:0,5 [1] )
+Markup span at (6:0,6 [1] ) - Parent: Tag block at (6:0,6 [8] )
+Markup span at (7:0,7 [5] ) - Parent: Markup block at (7:0,7 [5] )
+Markup span at (12:0,12 [2] ) - Parent: Tag block at (6:0,6 [8] )
+Markup span at (14:1,0 [3] ) - Parent: Tag block at (14:1,0 [3] )
+Markup span at (17:1,3 [7] ) - Parent: Markup block at (0:0,0 [68] )
+Markup span at (24:1,10 [4] ) - Parent: Tag block at (24:1,10 [4] )
+Markup span at (28:1,14 [11] ) - Parent: Markup block at (0:0,0 [68] )
+Markup span at (39:3,0 [3] ) - Parent: Tag block at (39:3,0 [3] )
+Markup span at (42:3,3 [8] ) - Parent: Markup block at (0:0,0 [68] )
+Markup span at (50:3,11 [4] ) - Parent: Tag block at (50:3,11 [4] )
+Markup span at (54:3,15 [14] ) - Parent: Markup block at (0:0,0 [68] )

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpBlockTest/GitConflictMarker_AtDocumentStart.stree.txt

@@ -0,0 +1,91 @@
+RazorDocument - [0..68)::68 - [<<<<<<< HEADLF<p>Current</p>LF=======LF<p>Incoming</p>LF>>>>>>> main]
+    MarkupBlock - [0..68)::68
+        MarkupElement - [0..1)::1
+            MarkupStartTag - [0..1)::1 - [<] - Gen<Markup>
+                OpenAngle;[<];
+                Text;[<Missing>];
+                CloseAngle;[<Missing>];
+        MarkupElement - [1..2)::1
+            MarkupStartTag - [1..2)::1 - [<] - Gen<Markup>
+                OpenAngle;[<];
+                Text;[<Missing>];
+                CloseAngle;[<Missing>];
+        MarkupElement - [2..3)::1
+            MarkupStartTag - [2..3)::1 - [<] - Gen<Markup>
+                OpenAngle;[<];
+                Text;[<Missing>];
+                CloseAngle;[<Missing>];
+        MarkupElement - [3..4)::1
+            MarkupStartTag - [3..4)::1 - [<] - Gen<Markup>
+                OpenAngle;[<];
+                Text;[<Missing>];
+                CloseAngle;[<Missing>];
+        MarkupElement - [4..5)::1
+            MarkupStartTag - [4..5)::1 - [<] - Gen<Markup>
+                OpenAngle;[<];
+                Text;[<Missing>];
+                CloseAngle;[<Missing>];
+        MarkupElement - [5..6)::1
+            MarkupStartTag - [5..6)::1 - [<] - Gen<Markup>
+                OpenAngle;[<];
+                Text;[<Missing>];
+                CloseAngle;[<Missing>];
+        MarkupElement - [6..14)::8
+            MarkupStartTag - [6..14)::8 - [< HEADLF] - Gen<Markup>
+                OpenAngle;[<];
+                Text;[<Missing>];
+                MarkupMinimizedAttributeBlock - [7..12)::5 - [ HEAD]
+                    MarkupTextLiteral - [7..8)::1 - [ ] - Gen<Markup>
+                        Whitespace;[ ];
+                    MarkupTextLiteral - [8..12)::4 - [HEAD] - Gen<Markup>
+                        Text;[HEAD];
+                MarkupMiscAttributeContent - [12..14)::2
+                    MarkupTextLiteral - [12..14)::2 - [LF] - Gen<Markup>
+                        NewLine;[LF];
+                CloseAngle;[<Missing>];
+        MarkupElement - [14..28)::14
+            MarkupStartTag - [14..17)::3 - [<p>] - Gen<Markup>
+                OpenAngle;[<];
+                Text;[p];
+                CloseAngle;[>];
+            MarkupTextLiteral - [17..24)::7 - [Current] - Gen<Markup>
+                Text;[Current];
+            MarkupEndTag - [24..28)::4 - [</p>] - Gen<Markup>
+                OpenAngle;[<];
+                ForwardSlash;[/];
+                Text;[p];
+                CloseAngle;[>];
+        MarkupTextLiteral - [28..39)::11 - [LF=======LF] - Gen<Markup>
+            NewLine;[LF];
+            Equals;[=];
+            Equals;[=];
+            Equals;[=];
+            Equals;[=];
+            Equals;[=];
+            Equals;[=];
+            Equals;[=];
+            NewLine;[LF];
+        MarkupElement - [39..54)::15
+            MarkupStartTag - [39..42)::3 - [<p>] - Gen<Markup>
+                OpenAngle;[<];
+                Text;[p];
+                CloseAngle;[>];
+            MarkupTextLiteral - [42..50)::8 - [Incoming] - Gen<Markup>
+                Text;[Incoming];
+            MarkupEndTag - [50..54)::4 - [</p>] - Gen<Markup>
+                OpenAngle;[<];
+                ForwardSlash;[/];
+                Text;[p];
+                CloseAngle;[>];
+        MarkupTextLiteral - [54..68)::14 - [LF>>>>>>> main] - Gen<Markup>
+            NewLine;[LF];
+            CloseAngle;[>];
+            CloseAngle;[>];
+            CloseAngle;[>];
+            CloseAngle;[>];
+            CloseAngle;[>];
+            CloseAngle;[>];
+            CloseAngle;[>];
+            Whitespace;[ ];
+            Text;[main];
+    EndOfFile;[];

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpBlockTest/GitConflictMarker_InCodeBlock.cspans.txt

@@ -0,0 +1,6 @@
+Markup span at (0:0,0 [0] ) - Parent: Markup block at (0:0,0 [84] )
+Transition span at (0:0,0 [1] ) - Parent: Statement block at (0:0,0 [84] )
+MetaCode span at (1:0,1 [1] ) - Parent: Statement block at (0:0,0 [84] )
+Code span at (2:0,2 [81] ) - Parent: Statement block at (0:0,0 [84] )
+MetaCode span at (83:6,0 [1] ) - Parent: Statement block at (0:0,0 [84] )
+Markup span at (84:6,1 [0] ) - Parent: Markup block at (0:0,0 [84] )

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpBlockTest/GitConflictMarker_InCodeBlock.stree.txt

@@ -0,0 +1,36 @@
+RazorDocument - [0..84)::84 - [@{LF<<<<<<< HEADLF    var x = 1;LF=======LF    var x = 2;LF>>>>>>> feature-branchLF}]
+    MarkupBlock - [0..84)::84
+        MarkupTextLiteral - [0..0)::0 - [] - Gen<Markup>
+            Marker;[];
+        CSharpCodeBlock - [0..84)::84
+            CSharpStatement - [0..84)::84
+                CSharpTransition - [0..1)::1 - Gen<None>
+                    Transition;[@];
+                CSharpStatementBody - [1..84)::83
+                    RazorMetaCode - [1..2)::1 - Gen<None>
+                        LeftBrace;[{];
+                    CSharpCodeBlock - [2..83)::81
+                        CSharpStatementLiteral - [2..83)::81 - [LF<<<<<<< HEADLF    var x = 1;LF=======LF    var x = 2;LF>>>>>>> feature-branchLF] - Gen<Stmt>
+                            NewLine;[LF];
+                            ConflictMarkerTrivia;[<<<<<<< HEAD];
+                            NewLine;[LF];
+                            Whitespace;[    ];
+                            Keyword;[var];
+                            Whitespace;[ ];
+                            Identifier;[x];
+                            Whitespace;[ ];
+                            Assign;[=];
+                            Whitespace;[ ];
+                            NumericLiteral;[1];
+                            Semicolon;[;];
+                            NewLine;[LF];
+                            ConflictMarkerTrivia;[=======];
+                            NewLine;[LF];
+                            CSharpDisabledText;[    var x = 2;LF];
+                            ConflictMarkerTrivia;[>>>>>>> feature-branch];
+                            NewLine;[LF];
+                    RazorMetaCode - [83..84)::1 - Gen<None>
+                        RightBrace;[}];
+        MarkupTextLiteral - [84..84)::0 - [] - Gen<Markup>
+            Marker;[];
+    EndOfFile;[];

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpBlockTest/GitConflictMarker_InExpression.cspans.txt

@@ -0,0 +1,6 @@
+Markup span at (0:0,0 [0] ) - Parent: Markup block at (0:0,0 [75] )
+Transition span at (0:0,0 [1] ) - Parent: Expression block at (0:0,0 [75] )
+MetaCode span at (1:0,1 [1] ) - Parent: Expression block at (0:0,0 [75] )
+Code span at (2:0,2 [72] ) - Parent: Expression block at (0:0,0 [75] )
+MetaCode span at (74:6,0 [1] ) - Parent: Expression block at (0:0,0 [75] )
+Markup span at (75:6,1 [0] ) - Parent: Markup block at (0:0,0 [75] )

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpBlockTest/GitConflictMarker_InExpression.stree.txt

@@ -0,0 +1,28 @@
+RazorDocument - [0..75)::75 - [@(LF<<<<<<< HEADLFsomeValueLF=======LFotherValueLF>>>>>>> feature-branchLF)]
+    MarkupBlock - [0..75)::75
+        MarkupTextLiteral - [0..0)::0 - [] - Gen<Markup>
+            Marker;[];
+        CSharpCodeBlock - [0..75)::75
+            CSharpExplicitExpression - [0..75)::75
+                CSharpTransition - [0..1)::1 - Gen<None>
+                    Transition;[@];
+                CSharpExplicitExpressionBody - [1..75)::74
+                    RazorMetaCode - [1..2)::1 - Gen<None>
+                        LeftParenthesis;[(];
+                    CSharpCodeBlock - [2..74)::72
+                        CSharpExpressionLiteral - [2..74)::72 - [LF<<<<<<< HEADLFsomeValueLF=======LFotherValueLF>>>>>>> feature-branchLF] - Gen<Expr>
+                            NewLine;[LF];
+                            ConflictMarkerTrivia;[<<<<<<< HEAD];
+                            NewLine;[LF];
+                            Identifier;[someValue];
+                            NewLine;[LF];
+                            ConflictMarkerTrivia;[=======];
+                            NewLine;[LF];
+                            CSharpDisabledText;[otherValueLF];
+                            ConflictMarkerTrivia;[>>>>>>> feature-branch];
+                            NewLine;[LF];
+                    RazorMetaCode - [74..75)::1 - Gen<None>
+                        RightParenthesis;[)];
+        MarkupTextLiteral - [75..75)::0 - [] - Gen<Markup>
+            Marker;[];
+    EndOfFile;[];

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpBlockTest/GitConflictMarker_InImplicitExpression.cspans.txt

@@ -0,0 +1,12 @@
+Markup span at (0:0,0 [3] ) - Parent: Tag block at (0:0,0 [3] )
+Transition span at (3:0,3 [1] ) - Parent: Expression block at (3:0,3 [1] )
+Code span at (4:0,4 [0] ) - Parent: Expression block at (3:0,3 [1] )
+Markup span at (4:0,4 [1] ) - Parent: Tag block at (4:0,4 [1] )
+Markup span at (5:0,5 [1] ) - Parent: Tag block at (5:0,5 [1] )
+Markup span at (6:0,6 [1] ) - Parent: Tag block at (6:0,6 [1] )
+Markup span at (7:0,7 [1] ) - Parent: Tag block at (7:0,7 [1] )
+Markup span at (8:0,8 [1] ) - Parent: Tag block at (8:0,8 [1] )
+Markup span at (9:0,9 [1] ) - Parent: Tag block at (9:0,9 [1] )
+Markup span at (10:0,10 [1] ) - Parent: Tag block at (10:0,10 [6] )
+Markup span at (11:0,11 [5] ) - Parent: Markup block at (11:0,11 [5] )
+Markup span at (16:0,16 [4] ) - Parent: Tag block at (16:0,16 [4] )

src/Compiler/Microsoft.AspNetCore.Razor.Language/test/TestFiles/ParserTests/CSharpBlockTest/GitConflictMarker_InImplicitExpression.diag.txt

@@ -0,0 +1 @@
+(1,5): Error RZ1005: "<<" is not valid at the start of a code block.  Only identifiers, keywords, comments, "(" and "{" are valid.