SwiftParser allows inconsistent spacing around `=`

[allevato]

Issue Kind

Bad Diagnostic Produced

Source Code

let x= 5

Description

In swiftc, this produces an error:

$ swiftc -Xfrontend -emit-syntax - <<'EOF'
heredoc> let x= 5
heredoc> EOF

<stdin>:1:6: error: '=' must have consistent whitespace on both sides
let x= 5
     ^

In SwiftParser, a valid syntax tree is produced with no diagnostics:

$ .build/debug/swift-parser-test print-diags <<'EOF'
let x= 5
EOF

No diagnostics produced

$ .build/debug/swift-parser-test dump-tree <<'EOF'
let x= 5
EOF

SourceFileSyntax children=2
  0: CodeBlockItemListSyntax children=1
    0: CodeBlockItemSyntax children=1
      0: VariableDeclSyntax children=2
        0: letKeyword
        1: PatternBindingListSyntax children=1
          0: PatternBindingSyntax children=2
            0: IdentifierPatternSyntax children=1
              0: identifier("x")
            1: InitializerClauseSyntax children=2
              0: equal
              1: IntegerLiteralExprSyntax children=1
                0: integerLiteral("5")
  1: eof

This is not limited to just InitializerClauseSyntax bindings; assignments to already-declared variables via AssignmentExprSyntax exhibit the same behavior.

[ahoppen]

rdar://100158607

[kimdv]

@allevato I think this was resolved in #1456

[allevato]

Yes, this is now fixed at HEAD:

$ .build/debug/swift-parser-cli print-diags <<'EOF'
let x= 5
x =5
EOF
=== stdin:1 ===
1 │ let x= 5
  │      ╰─ error: '=' must have consistent whitespace on both sides
2 │ x =5
  │    ╰─ error: '=' must have consistent whitespace on both sides
3 │

Thank you @kimdv!

Fixed by #1456.