During which phase of a compiler is the grammar of a program checked?

Concept

A compiler front end processes source code in successive stages. Lexical analysis forms tokens, syntax analysis parses those tokens according to a grammar, and semantic analysis checks meaning-related constraints such as types and declarations.

A programming-language grammar consists of production rules. A parser checks whether the token sequence can be organized according to those rules and constructs a parse tree or an abstract syntax tree.

Application

The stem asks specifically about checking the grammar of a program. That operation is parsing, so it belongs to syntax analysis.

Contrast

• Semantic analysis checks type compatibility, declarations, and other meaning-related rules after a parse structure exists.

• Code generation converts an intermediate representation into target code.

• Syntax analysis checks grammatical structure by parsing tokens with grammar productions.

• Code optimization improves a representation without changing program behavior.

Therefore, the grammar of a program is checked during syntax analysis.