Allow interleaving of STDOUT and STDERR check lines. Put STDOUT lines
after the line they're attached to, and STDERR lines before. If no
STDOUT check line is attached to any line, then put them all at the end
of the file instead.
This is intended to better handle the case where stdout contains
unreplaced mentions of line numbers, and also reflects that stdout is
typically a consequence of the test rather than commentary on it, so
placing it after the test seems likely to read better.
Prevent copies when initializing value expression from reference
expression. This is based on
https://github.com/carbon-language/carbon-lang/pull/2006, which
introduces expression categories, and how it is possible to convert
to/from those different categories. Continuation of
https://github.com/carbon-language/carbon-lang/pull/2907
## Functional changes
* Initializing a value expression from a reference expression takes its
value without a copy
* Reading from the value expression causes an error if the value changed
from the time it was initialized
* In this situation, prevents a copy both for variable definitions, and
call parameter bindings
## Main implementation changes
* Add new `ExpressionCategoryAction`, which evaluates an expression and
returns an `ExpressionValue` containing its category and address (if
any), in addition to the resulting `Value*`
* `ExpressionAction`s now invokes `ExpressionCategoryAction` and unwraps
the returned `ExpressionValue`
* `RuntimeScope::BindAndPin` method, and corresponding when attempting
to read a `value_node`.
## Next work
* Avoid unnecessary copies from value expression to value expression,
after ensuring that even value expression temporaries are registered for
destruction (https://github.com/Pixep/carbon-lang/pull/9)
Add partial support for initializing expressions for variable declaration. This is based on https://github.com/carbon-language/carbon-lang/pull/2006, which introduces expression categories, and how it is possible to convert to/from those different categories.
## Functional changes
* Initializing expressions initialize directly the provided storage when used to initialize a variable.
* Allows initializing expressions to avoid a copy when using `[var|let] name: type = call_expression(...)` by initializing `name` in-place.
* Support `returned var: ...` and `return <expr>`
* Support nested initializing expressions
## Main implementation changes
* Updated PatternMatch logic to handle expression categories
* Updated `VariableDefinition` interpreter statement to allocate and pass a location to initializing expressions
* Update statement actions to allow passing an allocation, used by return expr or returned var
* Modified the RuntimeScope API to be one step closer to the memory model we want to have
* Remove `GetAllocationId` and older `Bind` which don't apply
* New set of tests to highlight those different situations
* Added a new intrinsic to print the allocation stack (and make sure we behave correctly, beyond visible side effects)
## Next work
* Dedicated `Action` to retrieve expression category information in the interpreter (https://github.com/carbon-language/carbon-lang/pull/2927)
* Avoid copies when initializing value expression from reference expression and prevent mutations for the duration of the "pinning" (https://github.com/carbon-language/carbon-lang/pull/2927)
* Avoid unnecessary copies from value expression to value expression, after ensuring that even value expression temporaries are registered for destruction.
* Avoid unnecessary copies when binding function arguments
Richard Smith
Adrien Leravat