Rollup merge of rust-lang#49707 - steveklabnik:rustc-book, r=QuietMisdreavus

Add "the Rustc book"

This PR introduces a new book into the documentation, "The rustc book". We already have books for Cargo, and for Rustdoc, rustc should have some too. This book is focused on *users* of rustc, and provides a nice place to write documentation for users.

I haven't put content here, but plan on scaffolding it out very soon, and wanted this PR open for a few discussions first. One of those is "what exactly should said TOC be?" I plan on having a proposed one up tomorrow, but figured I'd let people know to start thinking about it now.

The big one is that we also will want to put https://github.com/rust-lang-nursery/rustc-guide in-tree as well, and the naming is... tough. I'm proposing:

* doc.rust-lang.org/rustc is "The Rustc book", to mirror the other tools' books.
* doc.rust-lang.org/rustc-contribution is "The Rustc contribution guide", and contains that book

@nikomatsakis et al, any thoughts on this? I'm not attached to it in particular, but had to put something together to get this discussion going. I think mirroring the other tools is a good idea for this work, but am not sure where exactly that leaves yours.

Fixes rust-docs/team#11

Author: kennytm

src/bootstrap/builder.rs

@@ -323,15 +323,15 @@ impl<'a> Builder<'a> {
                 test::Cargotest, test::Cargo, test::Rls, test::ErrorIndex, test::Distcheck,
                 test::RunMakeFullDeps,
                 test::Nomicon, test::Reference, test::RustdocBook, test::RustByExample,
-                test::TheBook, test::UnstableBook,
+                test::TheBook, test::UnstableBook, test::RustcBook,
                 test::Rustfmt, test::Miri, test::Clippy, test::RustdocJS, test::RustdocTheme,
                 // Run run-make last, since these won't pass without make on Windows
                 test::RunMake, test::RustdocUi),
             Kind::Bench => describe!(test::Crate, test::CrateLibrustc),
             Kind::Doc => describe!(doc::UnstableBook, doc::UnstableBookGen, doc::TheBook,
                 doc::Standalone, doc::Std, doc::Test, doc::WhitelistedRustc, doc::Rustc,
                 doc::ErrorIndex, doc::Nomicon, doc::Reference, doc::Rustdoc, doc::RustByExample,
-                doc::CargoBook),
+                doc::RustcBook, doc::CargoBook),
             Kind::Dist => describe!(dist::Docs, dist::RustcDocs, dist::Mingw, dist::Rustc,
                 dist::DebuggerScripts, dist::Std, dist::Analysis, dist::Src,
                 dist::PlainSourceTarball, dist::Cargo, dist::Rls, dist::Rustfmt, dist::Extended,

src/bootstrap/doc.rs

@@ -71,6 +71,7 @@ book!(
     Nomicon, "src/doc/nomicon", "nomicon";
     Reference, "src/doc/reference", "reference";
     Rustdoc, "src/doc/rustdoc", "rustdoc";
+    RustcBook, "src/doc/rustc", "rustc";
     RustByExample, "src/doc/rust-by-example", "rust-by-example";
 );
 

src/bootstrap/test.rs

@@ -1212,6 +1212,7 @@ test_book!(
     Nomicon, "src/doc/nomicon", "nomicon", default=false;
     Reference, "src/doc/reference", "reference", default=false;
     RustdocBook, "src/doc/rustdoc", "rustdoc", default=true;
+    RustcBook, "src/doc/rustc", "rustc", default=true;
     RustByExample, "src/doc/rust-by-example", "rust-by-example", default=false;
     TheBook, "src/doc/book", "book", default=false;
     UnstableBook, "src/doc/unstable-book", "unstable-book", default=true;

src/doc/index.md

@@ -43,6 +43,10 @@ Rust's standard library has [extensive API documentation](std/index.html),
 with explanations of how to use various things, as well as example code for
 accomplishing various tasks.
 
+## The Rustc Book
+
+[The Rustc Book](rustc/index.html) describes the Rust compiler, `rustc`.
+
 ## The Cargo Book
 
 [The Cargo Book](cargo/index.html) is a guide to Cargo, Rust's build tool and dependency manager.

src/doc/rustc/.gitignore

@@ -0,0 +1 @@
+book

src/doc/rustc/book.toml

@@ -0,0 +1,5 @@
+[book]
+authors = ["The Rust Project Developers"]
+multilingual = false
+src = "src"
+title = "The rustc book"

src/doc/rustc/src/SUMMARY.md

@@ -0,0 +1,16 @@
+# The Rustc Book
+
+- [What is rustc?](what-is-rustc.md)
+- [Command-line arguments](command-line-arguments.md)
+- [Lints](lints/index.md)
+    - [Lint levels](lints/levels.md)
+    - [Lint Groups](lints/groups.md)
+    - [Lint listing](lints/listing/index.md)
+        - [Allowed-by-default lints](lints/listing/allowed-by-default.md)
+        - [Warn-by-default lints](lints/listing/warn-by-default.md)
+        - [Deny-by-default lints](lints/listing/deny-by-default.md)
+- [Codegen options](codegen-options/index.md)
+- [Targets](targets/index.md)
+    - [Built-in Targets](targets/built-in.md)
+    - [Custom Targets](targets/custom.md)
+- [Contributing to `rustc`](contributing.md)

src/doc/rustc/src/codegen-options/index.md

@@ -0,0 +1,209 @@
+# Codegen options
+
+All of these options are passed to `rustc` via the `-C` flag, short for "codegen." You can see
+a version of this list for your exact compiler by running `rustc -C help`.
+
+## ar
+
+This option is deprecated and does nothing.
+
+## linker
+
+This flag lets you control which linker `rustc` invokes to link your code.
+
+## link-arg=val
+
+This flag lets you append a single extra argument to the linker invocation.
+
+"Append" is significant; you can pass this flag multiple times to add multiple arguments.
+
+## link-args
+
+This flag lets you append multiple extra arguments to the linker invocation. The
+options should be separated by spaces.
+
+## link-dead-code
+
+Normally, the linker will remove dead code. This flag disables this behavior.
+
+An example of when this flag might be useful is when trying to construct code coverage
+metrics.
+
+## lto
+
+This flag instructs LLVM to use [link time
+optimizations](https://llvm.org/docs/LinkTimeOptimization.html).
+
+It takes one of two values, `thin` and `fat`. 'thin' LTO [is a new feature of
+LLVM](http://blog.llvm.org/2016/06/thinlto-scalable-and-incremental-lto.html),
+'fat' referring to the classic version of LTO.
+
+## target-cpu
+
+This instructs `rustc` to generate code specifically for a particular processor.
+
+You can run `rustc --print target-cpus` to see the valid options to pass
+here. Additionally, `native` can be passed to use the processor of the host
+machine.
+
+## target-feature
+
+Individual targets will support different features; this flag lets you control
+enabling or disabling a feature.
+
+To see the valid options and an example of use, run `rustc --print
+target-features`.
+
+## passes
+
+This flag can be used to add extra LLVM passes to the compilation.
+
+The list must be separated by spaces.
+
+## llvm-args
+
+This flag can be used to pass a list of arguments directly to LLVM.
+
+The list must be separated by spaces.
+
+## save-temps
+
+`rustc` will generate temporary files during compilation; normally it will
+delete them after it's done with its work. This option will cause them to be
+preserved instead of removed.
+
+## rpath
+
+This option allows you to set the value of
+[`rpath`](https://en.wikipedia.org/wiki/Rpath).
+
+## overflow-checks
+
+This flag allows you to control the behavior of integer overflow. This flag
+can be passed many options:
+
+* To turn overflow checks on: `y`, `yes`, or `on`.
+* To turn overflow checks off: `n`, `no`, or `off`.
+
+## no-prepopulate-passes
+
+The pass manager comes pre-populated with a list of passes; this flag
+ensures that list is empty.
+
+## no-vectorize-loops
+
+By default, `rustc` will attempt to [vectorize
+loops](https://llvm.org/docs/Vectorizers.html#the-loop-vectorizer). This
+flag will turn that behavior off.
+
+## no-vectorize-slp
+
+By default, `rustc` will attempt to vectorize loops using [superword-level
+parallelism](https://llvm.org/docs/Vectorizers.html#the-slp-vectorizer). This
+flag will turn that behavior off.
+
+## soft-float
+
+This option will make `rustc` generate code using "soft floats." By default,
+a lot of hardware supports floating point instructions, and so the code generated
+will take advantage of this. "soft floats" emulate floating point instructions
+in software.
+
+## prefer-dynamic
+
+By default, `rustc` prefers to statically link dependencies. This option will
+make it use dynamic linking instead.
+
+## no-integrated-as
+
+LLVM comes with an internal assembler; this option will let you use an
+external assembler instead.
+
+## no-redzone
+
+This flag allows you to disable [the
+red zone](https://en.wikipedia.org/wiki/Red_zone_\(computing\)). This flag can
+be passed many options:
+
+* To enable the red zone: `y`, `yes`, or `on`.
+* To disable it: `n`, `no`, or `off`.
+
+## relocation-model
+
+This option lets you choose which relocation model to use.
+
+To find the valid options for this flag, run `rustc --print relocation-models`.
+
+## code-model=val
+
+This option lets you choose which code model to use.
+
+To find the valid options for this flag, run `rustc --print code-models`.
+
+## metadata
+
+This option allows you to control the metadata used for symbol mangling.
+
+## extra-filename
+
+This option allows you to put extra data in each output filename.
+
+## codegen-units
+
+This flag lets you control how many threads are used when doing
+code generation.
+
+Increasing paralellism may speed up compile times, but may also
+produce slower code.
+
+## remark
+
+This flag lets you print remarks for these optimization passes.
+
+The list of passes should be separated by spaces.
+
+`all` will remark on every pass.
+
+## no-stack-check
+
+This option is deprecated and does nothing.
+
+## debuginfo
+
+This flag lets you control debug information:
+
+* `0`: no debug info at all
+* `1`: line tables only
+* `2`: full debug info
+
+## opt-level
+
+This flag lets you control the optimization level.
+
+* `0`: no optimizations
+* `1`: basic optimizations
+* `2`: some optimizations
+* `3`: all optimizations
+* `s`: optimize for binary size
+* `z`: optimize for binary size, but also turn off loop vectorization.
+
+## debug-assertions
+
+This flag lets you turn `cfg(debug_assertions)` on or off.
+
+## inline-threshold
+
+This option lets you set the threshold for inlining a function.
+
+The default is 225.
+
+## panic
+
+This option lets you control what happens when the code panics.
+
+* `abort`: terminate the process upon panic
+* `unwind`: unwind the stack upon panic
+
+## incremental
+
+This flag allows you to enable incremental compilation.

src/doc/rustc/src/command-line-arguments.md

@@ -0,0 +1,116 @@
+# Command-line arguments
+
+Here's a list of command-line arguments to `rustc` and what they do.
+
+## `-h`/`--help`: get help
+
+This flag will print out help information for `rustc`.
+
+## `--cfg`: configure the compilation environment
+
+This flag can turn on or off various `#[cfg]` settings.
+
+## `-L`: add a directory to the library search path
+
+When looking for external crates, a directory passed to this flag will be searched.
+
+## `-l`: link the generated crate to a native library
+
+This flag allows you to specify linking to a specific native library when building
+a crate.
+
+## `--crate-type`: a list of types of crates for the compiler to emit
+
+This instructs `rustc` on which crate type to build.
+
+## `--crate-name`: specify the name of the crate being built
+
+This informs `rustc` of the name of your crate.
+
+## `--emit`: emit output other than a crate
+
+Instead of producing a crate, this flag can print out things like the assembly or LLVM-IR.
+
+## `--print`: print compiler information
+
+This flag prints out various information about the compiler.
+
+## `-g`: include debug information
+
+A synonym for `-C debug-level=2`.
+
+## `-O`: optimize your code
+
+A synonym for `-C opt-level=2`.
+
+## `-o`: filename of the output
+
+This flag controls the output filename.
+
+## `--out-dir`: directory to write the output in
+
+The outputted crate will be written to this directory.
+
+## `--explain`: provide a detailed explanation of an error message
+
+Each error of `rustc`'s comes with an error code; this will print
+out a longer explanation of a given error.
+
+## `--test`: build a test harness
+
+When compiling this crate, `rustc` will ignore your `main` function
+and instead produce a test harness.
+
+## `--target`: select a target triple to build
+
+This controls which [target](targets/index.html) to produce.
+
+## `-W`: set lint warnings
+
+This flag will set which lints should be set to the [warn level](lints/levels.html#warn).
+
+## `-A`: set lint allowed
+
+This flag will set which lints should be set to the [allow level](lints/levels.html#allow).
+
+## `-D`: set lint denied
+
+This flag will set which lints should be set to the [deny level](lints/levels.html#deny).
+
+## `-F`: set lint forbidden
+
+This flag will set which lints should be set to the [forbid level](lints/levels.html#forbid).
+
+## `--cap-lints`: set the most restrictive lint level
+
+This flag lets you 'cap' lints, for more, [see here](lints/levels.html#capping-lints).
+
+## `-C`/`--codegen`: code generation options
+
+This flag will allow you to set [codegen options](codegen-options/index.html).
+
+## `-V`/`--version`: print a version
+
+This flag will print out `rustc`'s version.
+
+## `-v`/`--verbose`: use verbose output
+
+This flag, when combined with other flags, makes them produce extra output.
+
+## `--extern`: specify where an external library is located
+
+This flag allows you to pass the name and location of an external crate that will
+be linked into the crate you're buildling.
+
+## `--sysroot`: Override the system root
+
+The "sysroot" is where `rustc` looks for the crates that come with the Rust
+distribution; this flag allows that to be overridden.
+
+## `--error-format`: control how errors are produced
+
+This flag lets you control the format of errors.
+
+## `--color`: configure coloring of output
+
+This flag lets you control color settings of the output.