A negative or integer literal used as a call receiver is not parenthesised: -2.5.abs() negates the result, and 5.toString() is a syntax error

[matt-edmondson]

What's wrong

Coder/Languages/LanguageGeneratorBase.cs:559-563: GenerateCallExpression writes GenerateInternal(callExpr.Receiver) followed by . and never wraps the receiver.

PR #92 added the LeadingSign handling (around line 699), but it only covers the unary-minus operand. A signed literal used as a receiver still loses its grouping.

Failure scenario

Signed literal receiver

new CallExpression(Literal.DecimalValue(-2.5), "__abs__") (or "abs") generates -2.5.abs(). C#, C++, Go, Rust, Python and JavaScript all do this, and C# writes -2.5d.abs().

Unary minus binds looser than member access, so this means -(2.5.abs()). In Python, -2.5.__abs__() evaluates to -2.5, while (-2.5).__abs__() gives 2.5. The generated code runs and returns the wrong value, with no error.

Integer literal receiver

new CallExpression(Literal.Number(5), "toString") generates 5.toString(). The output doesn't parse:

• Node: SyntaxError: Invalid or unexpected token
• Python: SyntaxError: invalid decimal literal

-5.toString() is also a SyntaxError in Node.

I reproduced these by running the built ktsu.Coder.dll and executing its output with python3 and node.

Suggested fix / acceptance criteria

• In GenerateCallExpression, parenthesise a receiver that is a literal with a leading sign. The existing LeadingSign helper can do this.
• Also parenthesise a bare integer literal receiver, at least for Python and JavaScript.
• Add generator tests:
  • (-2.5).abs() for every language
  • (5).toString() for JavaScript and Python

[matt-edmondson]

Triage

• Category: Bug
• Priority: High. For a signed literal receiver, the generated code runs and returns the wrong value with no error (-2.5.abs() gives -2.5 in every target language). For an integer receiver, the JS and Python output does not parse.
• Area / suggested assignee: shared expression emission in LanguageGeneratorBase.cs (GenerateCallExpression, LeadingSign). Owner: @matt-edmondson
• Duplicates / in progress: no duplicate or open PR. This is a follow-up to the incomplete fix in merged PR Parenthesise a negative literal under a unary minus #92, which covered only the unary-minus operand.
• Next step: wrap a signed literal receiver in parentheses (in every language) and a bare integer literal receiver (JS/Python at least), then add the per-language (-2.5).abs() and (5).toString() tests.

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