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| <ol class="chapter"><li class="chapter-item affix "><a href="about-this-guide.html">About this guide</a></li><li class="chapter-item affix "><a href="getting-started.html">Getting Started</a></li><li class="spacer"></li><li class="chapter-item affix "><li class="part-title">Building and debugging rustc</li><li class="chapter-item "><a href="building/how-to-build-and-run.html"><strong aria-hidden="true">1.</strong> How to Build and Run the Compiler</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="building/prerequisites.html"><strong aria-hidden="true">1.1.</strong> Prerequisites</a></li><li class="chapter-item "><a href="building/suggested.html"><strong aria-hidden="true">1.2.</strong> Suggested Workflows</a></li><li class="chapter-item "><a href="building/build-install-distribution-artifacts.html"><strong aria-hidden="true">1.3.</strong> Distribution artifacts</a></li><li class="chapter-item "><a href="building/compiler-documenting.html"><strong aria-hidden="true">1.4.</strong> Documenting Compiler</a></li><li class="chapter-item "><a href="rustdoc.html"><strong aria-hidden="true">1.5.</strong> Rustdoc overview</a></li><li class="chapter-item "><a href="building/new-target.html"><strong aria-hidden="true">1.6.</strong> Adding a new target</a></li></ol></li><li class="chapter-item "><a href="tests/intro.html"><strong aria-hidden="true">2.</strong> The compiler testing framework</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="tests/running.html"><strong aria-hidden="true">2.1.</strong> Running tests</a></li><li class="chapter-item "><a href="tests/adding.html"><strong aria-hidden="true">2.2.</strong> Adding new tests</a></li><li class="chapter-item "><a href="compiletest.html"><strong aria-hidden="true">2.3.</strong> Using compiletest commands to control test execution</a></li></ol></li><li class="chapter-item "><a href="compiler-debugging.html"><strong aria-hidden="true">3.</strong> Debugging the Compiler</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="tracing.html"><strong aria-hidden="true">3.1.</strong> Using the tracing/logging instrumentation</a></li></ol></li><li class="chapter-item "><a href="profiling.html"><strong aria-hidden="true">4.</strong> Profiling the compiler</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="profiling/with_perf.html"><strong aria-hidden="true">4.1.</strong> with the linux perf tool</a></li><li class="chapter-item "><a href="profiling/wpa_profiling.html"><strong aria-hidden="true">4.2.</strong> with Windows Performance Analyzer</a></li></ol></li><li class="chapter-item "><a href="crates-io.html"><strong aria-hidden="true">5.</strong> crates.io Dependencies</a></li><li class="chapter-item affix "><li class="part-title">Contributing to Rust</li><li class="chapter-item "><a href="contributing.html"><strong aria-hidden="true">6.</strong> Introduction</a></li><li class="chapter-item "><a href="compiler-team.html"><strong aria-hidden="true">7.</strong> About the compiler team</a></li><li class="chapter-item "><a href="git.html"><strong aria-hidden="true">8.</strong> Using Git</a></li><li class="chapter-item "><a href="rustbot.html"><strong aria-hidden="true">9.</strong> Mastering @rustbot</a></li><li class="chapter-item "><a href="walkthrough.html"><strong aria-hidden="true">10.</strong> Walkthrough: a typical contribution</a></li><li class="chapter-item "><a href="bug-fix-procedure.html"><strong aria-hidden="true">11.</strong> Bug Fix Procedure</a></li><li class="chapter-item "><a href="implementing_new_features.html"><strong aria-hidden="true">12.</strong> Implementing new features</a></li><li class="chapter-item "><a href="stability.html"><strong aria-hidden="true">13.</strong> Stability attributes</a></li><li class="chapter-item "><a href="stabilization_guide.html"><strong aria-hidden="true">14.</strong> Stabilizing Features</a></li><li class="chapter-item "><a href="feature-gates.html"><strong aria-hidden="true">15.</strong> Feature Gates</a></li><li class="chapter-item "><a href="conventions.html"><strong aria-hidden="true">16.</strong> Coding conventions</a></li><li class="chapter-item "><a href="notification-groups/about.html"><strong aria-hidden="true">17.</strong> Notification groups</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="notification-groups/arm.html"><strong aria-hidden="true">17.1.</strong> ARM</a></li><li class="chapter-item "><a href="notification-groups/cleanup-crew.html"><strong aria-hidden="true">17.2.</strong> Cleanup Crew</a></li><li class="chapter-item "><a href="notification-groups/llvm.html"><strong aria-hidden="true">17.3.</strong> LLVM</a></li><li class="chapter-item "><a href="notification-groups/risc-v.html"><strong aria-hidden="true">17.4.</strong> RISC-V</a></li><li class="chapter-item "><a href="notification-groups/windows.html"><strong aria-hidden="true">17.5.</strong> Windows</a></li></ol></li><li class="chapter-item "><a href="licenses.html"><strong aria-hidden="true">18.</strong> Licenses</a></li><li class="chapter-item affix "><li class="part-title">High-level Compiler Architecture</li><li class="chapter-item "><a href="part-2-intro.html"><strong aria-hidden="true">19.</strong> Prologue</a></li><li class="chapter-item "><a href="overview.html"><strong aria-hidden="true">20.</strong> Overview of the Compiler</a></li><li class="chapter-item expanded "><a href="compiler-src.html" class="active"><strong aria-hidden="true">21.</strong> The compiler source code</a></li><li class="chapter-item "><a href="building/bootstrapping.html"><strong aria-hidden="true">22.</strong> Bootstrapping</a></li><li class="chapter-item "><a href="query.html"><strong aria-hidden="true">23.</strong> Queries: demand-driven compilation</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="queries/query-evaluation-model-in-detail.html"><strong aria-hidden="true">23.1.</strong> The Query Evaluation Model in Detail</a></li><li class="chapter-item "><a href="queries/incremental-compilation.html"><strong aria-hidden="true">23.2.</strong> Incremental compilation</a></li><li class="chapter-item "><a href="queries/incremental-compilation-in-detail.html"><strong aria-hidden="true">23.3.</strong> Incremental compilation In Detail</a></li><li class="chapter-item "><a href="incrcomp-debugging.html"><strong aria-hidden="true">23.4.</strong> Debugging and Testing</a></li><li class="chapter-item "><a href="salsa.html"><strong aria-hidden="true">23.5.</strong> Salsa</a></li></ol></li><li class="chapter-item "><a href="memory.html"><strong aria-hidden="true">24.</strong> Memory Management in Rustc</a></li><li class="chapter-item "><a href="serialization.html"><strong aria-hidden="true">25.</strong> Serialization in Rustc</a></li><li class="chapter-item "><a href="parallel-rustc.html"><strong aria-hidden="true">26.</strong> Parallel Compilation</a></li><li class="chapter-item "><a href="rustdoc-internals.html"><strong aria-hidden="true">27.</strong> Rustdoc internals</a></li><li class="chapter-item affix "><li class="part-title">Source Code Representation</li><li class="chapter-item "><a href="part-3-intro.html"><strong aria-hidden="true">28.</strong> Prologue</a></li><li class="chapter-item "><a href="cli.html"><strong aria-hidden="true">29.</strong> Command-line arguments</a></li><li class="chapter-item "><a href="rustc-driver.html"><strong aria-hidden="true">30.</strong> The Rustc Driver and Interface</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="rustc-driver-interacting-with-the-ast.html"><strong aria-hidden="true">30.1.</strong> Ex: Type checking through rustc_interface</a></li><li class="chapter-item "><a href="rustc-driver-getting-diagnostics.html"><strong aria-hidden="true">30.2.</strong> Ex: Getting diagnostics through rustc_interface</a></li></ol></li><li class="chapter-item "><a href="syntax-intro.html"><strong aria-hidden="true">31.</strong> Syntax and the AST</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="the-parser.html"><strong aria-hidden="true">31.1.</strong> Lexing and Parsing</a></li><li class="chapter-item "><a href="macro-expansion.html"><strong aria-hidden="true">31.2.</strong> Macro expansion</a></li><li class="chapter-item "><a href="name-resolution.html"><strong aria-hidden="true">31.3.</strong> Name resolution</a></li><li class="chapter-item "><a href="test-implementation.html"><strong aria-hidden="true">31.4.</strong> #[test] Implementation</a></li><li class="chapter-item "><a href="panic-implementation.html"><strong aria-hidden="true">31.5.</strong> Panic Implementation</a></li><li class="chapter-item "><a href="ast-validation.html"><strong aria-hidden="true">31.6.</strong> AST Validation</a></li><li class="chapter-item "><a href="feature-gate-ck.html"><strong aria-hidden="true">31.7.</strong> Feature Gate Checking</a></li><li class="chapter-item "><a href="lang-items.html"><strong aria-hidden="true">31.8.</strong> Lang Items</a></li></ol></li><li class="chapter-item "><a href="hir.html"><strong aria-hidden="true">32.</strong> The HIR (High-level IR)</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="lowering.html"><strong aria-hidden="true">32.1.</strong> Lowering AST to HIR</a></li><li class="chapter-item "><a href="hir-debugging.html"><strong aria-hidden="true">32.2.</strong> Debugging</a></li></ol></li><li class="chapter-item "><a href="thir.html"><strong aria-hidden="true">33.</strong> The THIR (Typed High-level IR)</a></li><li class="chapter-item "><a href="mir/index.html"><strong aria-hidden="true">34.</strong> The MIR (Mid-level IR)</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="mir/construction.html"><strong aria-hidden="true">34.1.</strong> MIR construction</a></li><li class="chapter-item "><a href="mir/visitor.html"><strong aria-hidden="true">34.2.</strong> MIR visitor and traversal</a></li><li class="chapter-item "><a href="mir/passes.html"><strong aria-hidden="true">34.3.</strong> MIR passes: getting the MIR for a function</a></li></ol></li><li class="chapter-item "><a href="identifiers.html"><strong aria-hidden="true">35.</strong> Identifiers in the Compiler</a></li><li class="chapter-item "><a href="closure.html"><strong aria-hidden="true">36.</strong> Closure expansion</a></li><li class="chapter-item affix "><li class="part-title">Analysis</li><li class="chapter-item "><a href="part-4-intro.html"><strong aria-hidden="true">37.</strong> Prologue</a></li><li class="chapter-item "><a href="ty.html"><strong aria-hidden="true">38.</strong> The ty module: representing types</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="generics.html"><strong aria-hidden="true">38.1.</strong> Generics and substitutions</a></li><li class="chapter-item "><a href="ty-fold.html"><strong aria-hidden="true">38.2.</strong> TypeFolder and TypeFoldable</a></li><li class="chapter-item "><a href="generic_arguments.html"><strong aria-hidden="true">38.3.</strong> Generic arguments</a></li><li class="chapter-item "><a href="constants.html"><strong aria-hidden="true">38.4.</strong> Constants in the type system</a></li></ol></li><li class="chapter-item "><a href="type-inference.html"><strong aria-hidden="true">39.</strong> Type inference</a></li><li class="chapter-item "><a href="traits/resolution.html"><strong aria-hidden="true">40.</strong> Trait solving</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="early-late-bound.html"><strong aria-hidden="true">40.1.</strong> Early and Late Bound Parameters</a></li><li class="chapter-item "><a href="traits/hrtb.html"><strong aria-hidden="true">40.2.</strong> Higher-ranked trait bounds</a></li><li class="chapter-item "><a href="traits/caching.html"><strong aria-hidden="true">40.3.</strong> Caching subtleties</a></li><li class="chapter-item "><a href="traits/specialization.html"><strong aria-hidden="true">40.4.</strong> Specialization</a></li><li class="chapter-item "><a href="traits/chalk.html"><strong aria-hidden="true">40.5.</strong> Chalk-based trait solving</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="traits/lowering-to-logic.html"><strong aria-hidden="true">40.5.1.</strong> Lowering to logic</a></li><li class="chapter-item "><a href="traits/goals-and-clauses.html"><strong aria-hidden="true">40.5.2.</strong> Goals and clauses</a></li><li class="chapter-item "><a href="traits/canonical-queries.html"><strong aria-hidden="true">40.5.3.</strong> Canonical queries</a></li></ol></li></ol></li><li class="chapter-item "><a href="type-checking.html"><strong aria-hidden="true">41.</strong> Type checking</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="method-lookup.html"><strong aria-hidden="true">41.1.</strong> Method Lookup</a></li><li class="chapter-item "><a href="variance.html"><strong aria-hidden="true">41.2.</strong> Variance</a></li><li class="chapter-item "><a href="opaque-types-type-alias-impl-trait.html"><strong aria-hidden="true">41.3.</strong> Opaque Types</a></li></ol></li><li class="chapter-item "><a href="pat-exhaustive-checking.html"><strong aria-hidden="true">42.</strong> Pattern and Exhaustiveness Checking</a></li><li class="chapter-item "><a href="mir/dataflow.html"><strong aria-hidden="true">43.</strong> MIR dataflow</a></li><li class="chapter-item "><a href="borrow_check.html"><strong aria-hidden="true">44.</strong> The borrow checker</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="borrow_check/moves_and_initialization.html"><strong aria-hidden="true">44.1.</strong> Tracking moves and initialization</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="borrow_check/moves_and_initialization/move_paths.html"><strong aria-hidden="true">44.1.1.</strong> Move paths</a></li></ol></li><li class="chapter-item "><a href="borrow_check/type_check.html"><strong aria-hidden="true">44.2.</strong> MIR type checker</a></li><li class="chapter-item "><a href="borrow_check/region_inference.html"><strong aria-hidden="true">44.3.</strong> Region inference</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="borrow_check/region_inference/constraint_propagation.html"><strong aria-hidden="true">44.3.1.</strong> Constraint propagation</a></li><li class="chapter-item "><a href="borrow_check/region_inference/lifetime_parameters.html"><strong aria-hidden="true">44.3.2.</strong> Lifetime parameters</a></li><li class="chapter-item "><a href="borrow_check/region_inference/member_constraints.html"><strong aria-hidden="true">44.3.3.</strong> Member constraints</a></li><li class="chapter-item "><a href="borrow_check/region_inference/placeholders_and_universes.html"><strong aria-hidden="true">44.3.4.</strong> Placeholders and universes</a></li><li class="chapter-item "><a href="borrow_check/region_inference/closure_constraints.html"><strong aria-hidden="true">44.3.5.</strong> Closure constraints</a></li><li class="chapter-item "><a href="borrow_check/region_inference/error_reporting.html"><strong aria-hidden="true">44.3.6.</strong> Error reporting</a></li></ol></li><li class="chapter-item "><a href="borrow_check/two_phase_borrows.html"><strong aria-hidden="true">44.4.</strong> Two-phase-borrows</a></li></ol></li><li class="chapter-item "><a href="param_env.html"><strong aria-hidden="true">45.</strong> Parameter Environments</a></li><li class="chapter-item "><a href="diagnostics.html"><strong aria-hidden="true">46.</strong> Errors and Lints</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="diagnostics/sessiondiagnostic.html"><strong aria-hidden="true">46.1.</strong> Creating Errors With SessionDiagnostic</a></li><li class="chapter-item "><a href="diagnostics/lintstore.html"><strong aria-hidden="true">46.2.</strong> LintStore</a></li><li class="chapter-item "><a href="diagnostics/diagnostic-codes.html"><strong aria-hidden="true">46.3.</strong> Diagnostic Codes</a></li><li class="chapter-item "><a href="diagnostics/diagnostic-items.html"><strong aria-hidden="true">46.4.</strong> Diagnostic Items</a></li></ol></li><li class="chapter-item "><li class="part-title">MIR to Binaries</li><li class="chapter-item "><a href="part-5-intro.html"><strong aria-hidden="true">47.</strong> Prologue</a></li><li class="chapter-item "><a href="mir/optimizations.html"><strong aria-hidden="true">48.</strong> MIR optimizations</a></li><li class="chapter-item "><a href="mir/debugging.html"><strong aria-hidden="true">49.</strong> Debugging</a></li><li class="chapter-item "><a href="const-eval.html"><strong aria-hidden="true">50.</strong> Constant evaluation</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="miri.html"><strong aria-hidden="true">50.1.</strong> miri const evaluator</a></li></ol></li><li class="chapter-item "><a href="backend/monomorph.html"><strong aria-hidden="true">51.</strong> Monomorphization</a></li><li class="chapter-item "><a href="backend/lowering-mir.html"><strong aria-hidden="true">52.</strong> Lowering MIR</a></li><li class="chapter-item "><a href="backend/codegen.html"><strong aria-hidden="true">53.</strong> Code Generation</a><a 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aria-hidden="true">56.</strong> LLVM Source-Based Code Coverage</a></li><li class="chapter-item "><a href="sanitizers.html"><strong aria-hidden="true">57.</strong> Sanitizers Support</a></li><li class="chapter-item "><a href="debugging-support-in-rustc.html"><strong aria-hidden="true">58.</strong> Debugging Support in the Rust Compiler</a></li><li class="spacer"></li><li class="chapter-item affix "><a href="appendix/background.html">Appendix A: Background topics</a></li><li class="chapter-item affix "><a href="appendix/glossary.html">Appendix B: Glossary</a></li><li class="chapter-item affix "><a href="appendix/code-index.html">Appendix C: Code Index</a></li><li class="chapter-item affix "><a href="appendix/compiler-lecture.html">Appendix D: Compiler Lecture Series</a></li><li class="chapter-item affix "><a href="appendix/bibliography.html">Appendix E: Bibliography</a></li><li class="chapter-item affix "><a href="appendix/humorust.html">Appendix Z: HumorRust</a></li><li 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| <h1 id="high-level-overview-of-the-compiler-source"><a class="header" href="#high-level-overview-of-the-compiler-source">High-level overview of the compiler source</a></h1> |
| <ul> |
| <li><a href="#workspace-structure">Workspace structure</a></li> |
| <li><a href="#standard-library">Standard library</a></li> |
| <li><a href="#compiler">Compiler</a> |
| <ul> |
| <li><a href="#big-picture">Big picture</a></li> |
| </ul> |
| </li> |
| <li><a href="#rustdoc">rustdoc</a></li> |
| <li><a href="#tests">Tests</a></li> |
| <li><a href="#build-system">Build System</a></li> |
| <li><a href="#other">Other</a></li> |
| </ul> |
| <p>Now that we have <a href="./overview.html">seen what the compiler does</a>, let's take a |
| look at the structure of the contents of the rust-lang/rust repo.</p> |
| <h2 id="workspace-structure"><a class="header" href="#workspace-structure">Workspace structure</a></h2> |
| <p>The <code>rust-lang/rust</code> repository consists of a single large cargo workspace |
| containing the compiler, the standard libraries (<code>core</code>, <code>alloc</code>, <code>std</code>, |
| <code>proc_macro</code>, etc), and <code>rustdoc</code>, along with the build system and a bunch of |
| tools and submodules for building a full Rust distribution.</p> |
| <p>The repository consists of three main directories:</p> |
| <ul> |
| <li> |
| <p><code>compiler/</code> contains the source code for <code>rustc</code>. It consists of many crates |
| that together make up the compiler.</p> |
| </li> |
| <li> |
| <p><code>library/</code> contains the standard libraries (<code>core</code>, <code>alloc</code>, <code>std</code>, |
| <code>proc_macro</code>, <code>test</code>), as well as the Rust runtime (<code>backtrace</code>, <code>rtstartup</code>, |
| <code>lang_start</code>).</p> |
| </li> |
| <li> |
| <p><code>src/</code> contains the source code for rustdoc, clippy, cargo, the build system, |
| language docs, etc.</p> |
| </li> |
| </ul> |
| <h2 id="standard-library"><a class="header" href="#standard-library">Standard library</a></h2> |
| <p>The standard library crates are all in <code>library/</code>. They have intuitive names |
| like <code>std</code>, <code>core</code>, <code>alloc</code>, etc. There is also <code>proc_macro</code>, <code>test</code>, and |
| other runtime libraries.</p> |
| <p>This code is fairly similar to most other Rust crates except that it must be |
| built in a special way because it can use unstable features.</p> |
| <h2 id="compiler"><a class="header" href="#compiler">Compiler</a></h2> |
| <blockquote> |
| <p>You may find it helpful to read <a href="./overview.html">The Overview Chapter</a> first, |
| which gives an overview of how the compiler works. The crates mentioned in |
| this section implement the compiler, and are underneath <code>compiler/</code></p> |
| </blockquote> |
| <p>The <code>compiler/</code> crates all have names starting with <code>rustc_*</code>. These are a |
| collection of around 50 interdependent crates ranging in size from tiny to |
| huge. There is also the <code>rustc</code> crate which is the actual binary (i.e. the |
| <code>main</code> function); it doesn't actually do anything besides calling the |
| <code>rustc_driver</code> crate, which drives the various parts of compilation in other |
| crates.</p> |
| <p>The dependency structure of these crates is complex, but roughly it is |
| something like this:</p> |
| <ul> |
| <li><code>rustc</code> (the binary) calls <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_driver/fn.main.html"><code>rustc_driver::main</code></a>. |
| <ul> |
| <li><a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_driver/index.html"><code>rustc_driver</code></a> depends on a lot of other crates, but the main one is |
| <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_interface/index.html"><code>rustc_interface</code></a>. |
| <ul> |
| <li><a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_interface/index.html"><code>rustc_interface</code></a> depends on most of the other compiler crates. It |
| is a fairly generic interface for driving the whole compilation. |
| <ul> |
| <li>Most of the other <code>rustc_*</code> crates depend on <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/index.html"><code>rustc_middle</code></a>, |
| which defines a lot of central data structures in the compiler. |
| <ul> |
| <li><a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/index.html"><code>rustc_middle</code></a> and most of the other crates depend on a |
| handful of crates representing the early parts of the |
| compiler (e.g. the parser), fundamental data structures (e.g. |
| <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/struct.Span.html"><code>Span</code></a>), or error reporting: <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_data_structures/index.html"><code>rustc_data_structures</code></a>, |
| <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/index.html"><code>rustc_span</code></a>, <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_errors/index.html"><code>rustc_errors</code></a>, etc.</li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| <p>You can see the exact dependencies by reading the <code>Cargo.toml</code> for the various |
| crates, just like a normal Rust crate.</p> |
| <p>One final thing: <a href="https://github.com/rust-lang/rust/tree/master/src/"><code>src/llvm-project</code></a> is a submodule for our fork of LLVM. |
| During bootstrapping, LLVM is built and the <a href="https://github.com/rust-lang/rust/tree/master/compiler/rustc_llvm"><code>compiler/rustc_llvm</code></a> crate |
| contains rust wrappers around LLVM (which is written in C++), so that the |
| compiler can interface with it.</p> |
| <p>Most of this book is about the compiler, so we won't have any further |
| explanation of these crates here.</p> |
| <h3 id="big-picture"><a class="header" href="#big-picture">Big picture</a></h3> |
| <p>The dependency structure is influenced strongly by two main factors:</p> |
| <ol> |
| <li>Organization. The compiler is a <em>huge</em> codebase; it would be an impossibly |
| large crate. In part, the dependency structure reflects the code structure |
| of the compiler.</li> |
| <li>Compile time. By breaking the compiler into multiple crates, we can take |
| better advantage of incremental/parallel compilation using cargo. In |
| particular, we try to have as few dependencies between crates as possible so |
| that we don't have to rebuild as many crates if you change one.</li> |
| </ol> |
| <p>At the very bottom of the dependency tree are a handful of crates that are used |
| by the whole compiler (e.g. <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/index.html"><code>rustc_span</code></a>). The very early parts of the |
| compilation process (e.g. parsing and the AST) depend on only these.</p> |
| <p>Pretty soon after the AST is constructed, the compiler's <a href="./query.html">query system</a> |
| gets set up. The query system is set up in a clever way using function |
| pointers. This allows us to break dependencies between crates, allowing more |
| parallel compilation.</p> |
| <p>However, since the query system is defined in <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/index.html"><code>rustc_middle</code></a>, nearly all |
| subsequent parts of the compiler depend on this crate. It is a really large |
| crate, leading to long compile times. Some efforts have been made to move stuff |
| out of it with limited success. Another unfortunate side effect is that sometimes |
| related functionality gets scattered across different crates. For example, |
| linting functionality is scattered across earlier parts of the crate, |
| <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint/index.html"><code>rustc_lint</code></a>, <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/index.html"><code>rustc_middle</code></a>, and other places.</p> |
| <p>More generally, in an ideal world, it seems like there would be fewer, more |
| cohesive crates, with incremental and parallel compilation making sure compile |
| times stay reasonable. However, our incremental and parallel compilation haven't |
| gotten good enough for that yet, so breaking things into separate crates has |
| been our solution so far.</p> |
| <p>At the top of the dependency tree are the <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_interface/index.html"><code>rustc_interface</code></a> and |
| <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_driver/index.html"><code>rustc_driver</code></a> crates. <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_interface/index.html"><code>rustc_interface</code></a> is an unstable wrapper around the |
| query system that helps to drive the various stages of compilation. Other |
| consumers of the compiler may use this interface in different ways (e.g. |
| rustdoc or maybe eventually rust-analyzer). The <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_driver/index.html"><code>rustc_driver</code></a> crate first |
| parses command line arguments and then uses <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustc_interface/index.html"><code>rustc_interface</code></a> to drive the |
| compilation to completion.</p> |
| <h2 id="rustdoc"><a class="header" href="#rustdoc">rustdoc</a></h2> |
| <p>The bulk of <code>rustdoc</code> is in <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustdoc/index.html"><code>librustdoc</code></a>. However, the <code>rustdoc</code> binary |
| itself is <a href="https://github.com/rust-lang/rust/tree/master/src/tools/rustdoc"><code>src/tools/rustdoc</code></a>, which does nothing except call <a href="https://doc.rust-lang.org/nightly/nightly-rustc/rustdoc/fn.main.html"><code>rustdoc::main</code></a>.</p> |
| <p>There is also javascript and CSS for the rustdocs in <a href="https://github.com/rust-lang/rust/tree/master/src/tools/rustdoc-js"><code>src/tools/rustdoc-js</code></a> |
| and <a href="https://github.com/rust-lang/rust/tree/master/src/tools/rustdoc-themes"><code>src/tools/rustdoc-themes</code></a>.</p> |
| <p>You can read more about rustdoc in <a href="./rustdoc.html">this chapter</a>.</p> |
| <h2 id="tests"><a class="header" href="#tests">Tests</a></h2> |
| <p>The test suite for all of the above is in <a href="https://github.com/rust-lang/rust/tree/master/src/test"><code>src/test/</code></a>. You can read more |
| about the test suite <a href="./tests/intro.html">in this chapter</a>.</p> |
| <p>The test harness itself is in <a href="https://github.com/rust-lang/rust/tree/master/src/tools/compiletest"><code>src/tools/compiletest</code></a>.</p> |
| <h2 id="build-system"><a class="header" href="#build-system">Build System</a></h2> |
| <p>There are a number of tools in the repository just for building the compiler, |
| standard library, rustdoc, etc, along with testing, building a full Rust |
| distribution, etc.</p> |
| <p>One of the primary tools is <a href="https://github.com/rust-lang/rust/tree/master/src/bootstrap"><code>src/bootstrap</code></a>. You can read more about |
| bootstrapping <a href="./building/bootstrapping.html">in this chapter</a>. The process may also use other tools |
| from <code>src/tools/</code>, such as <a href="https://github.com/rust-lang/rust/tree/master/src/tools/tidy"><code>tidy</code></a> or <a href="https://github.com/rust-lang/rust/tree/master/src/tools/compiletest"><code>compiletest</code></a>.</p> |
| <h2 id="other"><a class="header" href="#other">Other</a></h2> |
| <p>There are a lot of other things in the <code>rust-lang/rust</code> repo that are related |
| to building a full rust distribution. Most of the time you don't need to worry |
| about them.</p> |
| <p>These include:</p> |
| <ul> |
| <li><a href="https://github.com/rust-lang/rust/tree/master/src/ci"><code>src/ci</code></a>: The CI configuration. This actually quite extensive because we |
| run a lot of tests on a lot of platforms.</li> |
| <li><a href="https://github.com/rust-lang/rust/tree/master/src/doc"><code>src/doc</code></a>: Various documentation, including submodules for a few books.</li> |
| <li><a href="https://github.com/rust-lang/rust/tree/master/src/etc"><code>src/etc</code></a>: Miscellaneous utilities.</li> |
| <li><a href="https://github.com/rust-lang/rust/tree/master/src/tools/rustc-workspace-hack"><code>src/tools/rustc-workspace-hack</code></a>, and others: Various workarounds to make |
| cargo work with bootstrapping.</li> |
| <li>And more...</li> |
| </ul> |
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