Semantic Analysis & Type Checking

By the end, you can

• Explain why a grammatically valid program can still fail semantic analysis.
• Describe what a symbol table stores and how it is used during name resolution.
• Trace a scope-stack lookup and predict which declaration shadows which.
• Identify undeclared-variable, type-mismatch, and wrong-arity errors in sample code.
• Walk a small AST bottom-up and assign types to each node.
• Distinguish static typing from dynamic typing, and explain why type inference is still static.
• Lower a simple arithmetic expression to three-address intermediate code.
• Explain what constant folding and dead-code elimination do and when they apply.