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Merge pull request #11726 from ethereum/yulScoping

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Clarify Yul scoping rules.
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Harikrishnan Mulackal 2021-08-03 12:41:24 +02:00 committed by GitHub
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@ -546,11 +546,18 @@ as explained below) and all declarations
introduce new identifiers into these scopes.
Identifiers are visible in
the block they are defined in (including all sub-nodes and sub-blocks).
the block they are defined in (including all sub-nodes and sub-blocks):
Functions are visible in the whole block (even before their definitions) while
variables are only visible starting from the statement after the ``VariableDeclaration``.
As an exception, the scope of the "init" part of the or-loop
In particular,
variables cannot be referenced in the right hand side of their own variable
declaration.
Functions can be referenced already before their declaration (if they are visible).
As an exception to the general scoping rule, the scope of the "init" part of the for-loop
(the first block) extends across all other parts of the for loop.
This means that variables declared in the init part (but not inside a
This means that variables (and functions) declared in the init part (but not inside a
block inside the init part) are visible in all other parts of the for-loop.
Identifiers declared in the other parts of the for loop respect the regular
@ -559,21 +566,15 @@ syntactical scoping rules.
This means a for-loop of the form ``for { I... } C { P... } { B... }`` is equivalent
to ``{ I... for {} C { P... } { B... } }``.
The parameters and return parameters of functions are visible in the
function body and their names have to be distinct.
Variables can only be referenced after their declaration. In particular,
variables cannot be referenced in the right hand side of their own variable
declaration.
Functions can be referenced already before their declaration (if they are visible).
Inside functions, it is not possible to reference a variable that was declared
outside of that function.
Shadowing is disallowed, i.e. you cannot declare an identifier at a point
where another identifier with the same name is also visible, even if it is
not accessible.
Inside functions, it is not possible to access a variable that was declared
outside of that function.
not possible to reference it because it was declared outside the current function.
Formal Specification
--------------------