Fix a crash in diagnostic generation if a primary associated type is not ended with a >

In the new test case, we were parsing `:` as a right angle, which caused a crash when we were retrieving the token’s kind in diagnostic generation.

Author: ahoppen

Sources/SwiftParser/Nominals.swift

@@ -258,7 +258,12 @@ extension Parser {
           arena: self.arena))
       } while keepGoing != nil && loopProgress.evaluate(currentToken)
     }
-    let rangle = self.consumeAnyToken(remapping: .rightAngle)
+    let rangle: RawTokenSyntax
+    if self.currentToken.starts(with: ">") {
+      rangle = self.consumePrefix(">", as: .rightAngle)
+    } else {
+      rangle = RawTokenSyntax(missing: .rightAngle, arena: self.arena)
+    }
     return RawPrimaryAssociatedTypeClauseSyntax(
       leftAngleBracket: langle,
       primaryAssociatedTypeList: RawPrimaryAssociatedTypeListSyntax(elements: associatedTypes, arena: self.arena),

Tests/SwiftParserTest/DeclarationTests.swift

@@ -1333,6 +1333,19 @@ final class DeclarationTests: XCTestCase {
       ]
     )
   }
+
+  func testPrimaryAssociatedTypeNotTerminatedWithAngleBracket() {
+    AssertParse(
+      "protocol1️⃣<2️⃣:3️⃣",
+      diagnostics: [
+        DiagnosticSpec(locationMarker: "1️⃣", message: "expected identifier in protocol"),
+        DiagnosticSpec(locationMarker: "2️⃣", message: "expected name in primary associated type clause"),
+        DiagnosticSpec(locationMarker: "2️⃣", message: "expected '>' to end primary associated type clause"),
+        DiagnosticSpec(locationMarker: "3️⃣", message: "expected type in type"),
+        DiagnosticSpec(locationMarker: "3️⃣", message: "expected member block in protocol"),
+      ]
+  )
+  }
 }
 
 extension Parser.DeclAttributes {