Suggest to add missing equal token to variable declarations

When a variable declaration is followed by an expression on the same line,
it should be suggested to insert an `equal` token

Author: whiteio

Sources/SwiftParser/Declarations.swift

@@ -1405,6 +1405,16 @@ extension Parser {
             value: initExpr,
             arena: self.arena
           )
+        } else if self.atStartOfExpression(), !self.at(.identifier, .wildcard, .leftBrace), !self.peek().rawTokenKind.is(.colon, .equal, .comma),
+          !self.currentToken.flags.contains(.isAtStartOfLine)
+        {
+          let missingEqual = RawTokenSyntax(missing: .equal, arena: self.arena)
+          let expr = self.parseExpression()
+          initializer = RawInitializerClauseSyntax(
+            equal: missingEqual,
+            value: expr,
+            arena: self.arena
+          )
         } else {
           initializer = nil
         }

Tests/SwiftParserTest/DeclarationTests.swift

@@ -2530,4 +2530,14 @@ final class DeclarationTests: XCTestCase {
         """
     )
   }
+
+  func testMissingEqualInVariableDeclaration() {
+    assertParse(
+      "let foo: [Int] 1️⃣[]",
+      diagnostics: [
+        DiagnosticSpec(locationMarker: "1️⃣", message: "expected '=' in variable", fixIts: ["insert '='"])
+      ],
+      fixedSource: "let foo: [Int] = []"
+    )
+  }
 }

Tests/SwiftParserTest/RegexLiteralTests.swift

@@ -1211,48 +1211,47 @@ final class RegexLiteralTests: XCTestCase {
   func testPrefixOpSplitting2a() {
     assertParse(
       """
-      let x1️⃣ .2️⃣/abc/
+      let x 1️⃣.2️⃣/abc/
       """,
       diagnostics: [
         DiagnosticSpec(
           locationMarker: "1️⃣",
-          message: "consecutive statements on a line must be separated by newline or ';'",
-          fixIts: ["insert newline", "insert ';'"]
+          message: "expected '=' in variable",
+          fixIts: ["insert '='"]
         ),
         DiagnosticSpec(
           locationMarker: "2️⃣",
           message: "expected name in member access",
           fixIts: ["insert name"]
         ),
       ],
-      applyFixIts: ["insert newline", "insert name"],
+      applyFixIts: ["insert '='", "insert name"],
       fixedSource: """
-        let x
-        .<#identifier#>/abc/
+        let x = .<#identifier#>/abc/
         """
     )
   }
 
   func testPrefixOpSplitting2b() {
     assertParse(
       """
-      let x1️⃣ .2️⃣/abc/
+      let x 1️⃣.2️⃣/abc/
       """,
       diagnostics: [
         DiagnosticSpec(
           locationMarker: "1️⃣",
-          message: "consecutive statements on a line must be separated by newline or ';'",
-          fixIts: ["insert newline", "insert ';'"]
+          message: "expected '=' in variable",
+          fixIts: ["insert '='"]
         ),
         DiagnosticSpec(
           locationMarker: "2️⃣",
           message: "expected name in member access",
           fixIts: ["insert name"]
         ),
       ],
-      applyFixIts: ["insert ';'", "insert name"],
+      applyFixIts: ["insert '='", "insert name"],
       fixedSource: """
-        let x; .<#identifier#>/abc/
+        let x = .<#identifier#>/abc/
         """
     )
   }

Tests/SwiftParserTest/translated/ForwardSlashRegexTests.swift

@@ -964,15 +964,16 @@ final class ForwardSlashRegexTests: XCTestCase {
     assertParse(
       """
       do {
-        let 1️⃣/x/ 
+        let 1️⃣/x/
       }
       """,
       diagnostics: [
-        DiagnosticSpec(message: "expected pattern in variable", fixIts: ["insert pattern"])
+        DiagnosticSpec(message: "expected pattern in variable", fixIts: ["insert pattern"]),
+        DiagnosticSpec(message: "expected '=' in variable", fixIts: ["insert '='"]),
       ],
       fixedSource: """
         do {
-          let <#pattern#>/x/
+          let <#pattern#> = /x/
         }
         """
     )