Which information belongs in a symbol table for semantic checking?

• Editor colours, line-wrapping preferences and current cursor positions
• Processor clock speeds, cache capacities and remaining battery charge
• Declaration kinds, types, scopes and function parameters

Here + requires two numbers and does not convert strings. n is a number and s is a string. Which expression has valid syntax but fails type checking?

• n + s
• n + )
• (n + n

Valid grammatical structure guarantees that code passes this lesson's static semantic checks.

In the lesson's symbol-table model, when are entries added and consulted?

• Uses create declarations; declarations later search the recorded name uses
• Parsing completes every name check; later stages never consult declarations
• Declarations add entries; name uses consult them under scope rules

paint takes three numbers, and red is a declared number. paint(red) has valid syntax. What information exposes its argument-count mismatch?

• The token entries saying paint and red are both names
• The declaration saying paint takes three parameters
• The target's instruction list specifying its visible registers

How can a shared IR support several languages and targets?

• Front ends produce it, and compatible target back ends consume it
• Each source language requires an incompatible IR for every target machine
• It replaces declaration checking by deleting all names from the source text

A name has valid token spelling and appears in a valid expression. What further information decides whether it is declared here?

• Only whether its letters match the language's identifier-token pattern
• Only whether its expression node occupies a valid grammatical position
• Which declaration is visible under the current scope rules, if any

Three existing back ends consume one IR. A new language can express all its operations in that IR. Which new component lets it reuse those back ends?

• Three new parsers, each emitting a different target's machine instructions
• One new front end translating the language into the shared IR
• One replacement symbol table removing all target-specific instructions