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https://github.com/carbon-language/carbon-lang.git
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Richard Smith
d50576ca16
When building an expression referencing the result of name lookup, if the lookup result is non-constant then check we can access it from the current scope. * If it is a global, then use a new `GlobalRef` instruction to get the value of that global. In lowering, create global variables to hold the values of global `let` bindings so that `GlobalRef` can access those values. * If it is a local, walk the lexical scopes between it and the point of use and ensure it is usable through from all of them. Error if there's an intervening declarative scope such as a class, add a TODO to handle captures for intervening functions, and allow `typeof(...)` to name things it can't read the value of since it's unevaluated. Global `let`s (which includes `let`s at class scope) now also have their initializers collected into the global inits block. If the initializer is non-constant, the wrapper binding also lives in the global inits block; otherwise it continues to live in the file block and the variable emitted for it is a global constant. Assisted-by: Gemini and Claude via Antigravity
50 lines
1.9 KiB
C++
50 lines
1.9 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "toolchain/check/full_pattern_stack.h"
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#include "toolchain/check/context.h"
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#include "toolchain/check/pattern.h"
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namespace Carbon::Check {
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auto FullPatternStack::StartPatternInitializer() -> void {
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CARBON_CHECK(IsAnyNameBindingDeclKind(kind_stack_.back()));
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for (auto& [name_id, inst_id] : bind_name_stack_.PeekArray()) {
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CARBON_CHECK(
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inst_id == SemIR::InstId::InitTombstone,
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"stashing the lookup result would overwrite an existing stash {0}",
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inst_id);
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auto& lookup_result = lookup_->Get(name_id);
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if (!lookup_result.empty()) {
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// Temporarily overwrite the result of name lookup for this binding to be
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// `InitTombstone`, so that references to it in the initializer are
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// diagnosed as errors. The original result of name lookup is stashed in
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// `bind_name_stack_` so we can restore it later.
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//
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// TODO: find a way to preserve location information, so that we can
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// provide good diagnostics for a redeclaration of `name_id` in
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// the initializer, if that becomes possible.
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std::swap(lookup_result.back().inst_id, inst_id);
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}
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}
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next_var_index_stack_.back() = 0;
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}
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auto FullPatternStack::EndPatternInitializer() -> void {
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for (auto& [name_id, inst_id] : bind_name_stack_.PeekArray()) {
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auto& lookup_result = lookup_->Get(name_id);
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if (!lookup_result.empty()) {
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// Restore the original result of name lookup for this binding.
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std::swap(lookup_result.back().inst_id, inst_id);
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}
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CARBON_CHECK(inst_id == SemIR::InstId::InitTombstone,
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"name_id resolved to a non-tombstone value {0} during "
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"initializer handling",
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inst_id);
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}
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}
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} // namespace Carbon::Check
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