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Adrien Leravat
19c74ead49
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