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Type errors (such as an attempt to apply the ++ increment operator to a Boolean variable in Java) and undeclared variable errors are sometimes considered to be syntax errors when they are detected at compile-time. It is common to classify such errors as (static) semantic errors instead. [2] [3] [4]
Semantic analysis or context sensitive analysis is a process in compiler construction, usually after parsing, to gather necessary semantic information from the source code. [1] It usually includes type checking , or makes sure a variable is declared before use which is impossible to describe in the extended Backus–Naur form and thus not ...
Denotational semantic descriptions can also serve as compositional translations from a programming language into the denotational metalanguage and used as a basis for designing compilers. Operational semantics , [ 7 ] whereby the execution of the language is described directly (rather than by translation).
Compiler analysis is the prerequisite for any compiler optimization, and they tightly work together. For example, dependence analysis is crucial for loop transformation. The scope of compiler analysis and optimizations vary greatly; their scope may range from operating within a basic block, to whole procedures, or even the whole program. There ...
The AST is used intensively during semantic analysis, where the compiler checks for correct usage of the elements of the program and the language. The compiler also generates symbol tables based on the AST during semantic analysis. A complete traversal of the tree allows verification of the correctness of the program.
For example, Rice's theorem implies that in dynamically typed programming languages which are Turing-complete, it is impossible to verify the absence of type errors. On the other hand, statically typed programming languages feature a type system which statically prevents type errors.
In computing, compiler correctness is the branch of computer science that deals with trying to show that a compiler behaves according to its language specification. [ citation needed ] Techniques include developing the compiler using formal methods and using rigorous testing (often called compiler validation) on an existing compiler.
Beaujolais effect is the name given to a class of potential semantic errors in Jean Ichbiah's draft specifications for the programming language Ada. The name arose from Ichbiah's promise to give a bottle of Beaujolais nouveau red wine to anyone who could find such a situation in the draft language standard. At least one bottle was actually ...