Merge pull request #3221 from fsprojects/repo-assist/fix-issue-2287-regression-test-eca76054b8d1726a

[Repo Assist] Add regression test for issue 2287: end of line comments after infix operators

Author: nojaf

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## [Unreleased]
+
+### Fixed
+
+- End of line comments after infix operators are preserved correctly. [#2287](https://github.com/fsprojects/fantomas/issues/2287)
+
 ## [8.0.0-alpha-002] - 2025-12-15
 
 ### Changed

src/Fantomas.Core.Tests/CommentTests.fs

@@ -2575,3 +2575,39 @@ let EnableHeapTerminationOnCorruption () =
                 )
             )
 """
+
+[<Test>]
+let ``end of line comments after infix operators are preserved correctly, 2287`` () =
+    formatSourceString
+        """
+// This function recognises these "infix operator" names.
+let IsMangledInfixOperator mangled  = (* where mangled is assumed to be a compiled name *) 
+    let afterSkipStarts     prefixes = Array.exists afterSkipStartsWith prefixes
+    s <> mangled && 
+    (s = ":="  ||                                    // COLON_EQUALS
+     afterSkipStarts relational ||                  // EQUALS, INFIX_COMPARE_OP, LESS, GREATER
+     s = "$" ||                                     // DOLLAR
+     afterSkipStarts concat ||                      // INFIX_AT_HAT_OP
+     s = "**")                                      // INFIX_STAR_STAR_OP
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+// This function recognises these "infix operator" names.
+let IsMangledInfixOperator mangled = (* where mangled is assumed to be a compiled name *)
+    let afterSkipStarts prefixes =
+        Array.exists afterSkipStartsWith prefixes
+
+    s <> mangled
+    && (s = ":="
+        || // COLON_EQUALS
+        afterSkipStarts relational
+        || // EQUALS, INFIX_COMPARE_OP, LESS, GREATER
+        s = "$"
+        || // DOLLAR
+        afterSkipStarts concat
+        || // INFIX_AT_HAT_OP
+        s = "**") // INFIX_STAR_STAR_OP
+"""