[Feature] Implement semantic analysis warnings using CompilableASTNode.checkForWarnings()

[Luna-Klatzer]

Is there an existing proposal for this?

• I have searched the existing issues

This feature does not exist in the latest version

• I am using the latest version

Proposal

Implement semantic analysis warnings using CompilableASTNode.checkForWarnings(), which is a specific function that will check for warnings during the semantic analysis of a program. If the user decides to disable warnings using a compile config flag, then this function is not called at all avoiding unnecessary checking.

This function should be called last after the primary semantic analysis, type checking and target-specific semantic analysis was finished and not called at all if an error occurred, even with recovery mode (#198).

Exact behaviour / changes you want

• Add new CLI flags -w/--warnings and --no-warnings.
• Add new abstract function CompilableASTNode.checkForWarnings(), which must be implemented by every child class.
• Implement system for handling warnings in CompilableASTNode.semanticAnalysis() and KipperProgramContext, which will keep track of all warnings.
• Add new field warnings in the class KipperCompileResult, which stores a list of all warnings.

[Luna-Klatzer]

This will be partially implemented in v0.9.0 and fully implemented with v0.10.0 using a new KipperWarningsChecker class that extends KipperSemanticErrorHandler. This should allow a similar error behaviour that is used in the KipperTypeChecker and KipperSemanticChecker.