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Fix heading levels in the query chapter #1305

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Feb 17, 2022
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Fix heading levels in the query chapter #1305

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14 changes: 7 additions & 7 deletions src/query.md
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ compiler (for example, generating [MIR](./mir/)) currently work exactly like thi
in-depth description of what queries are and how they work.
If you intend to write a query of your own, this is a good read.

### Invoking queries
## Invoking queries

Invoking a query is simple. The [`TyCtxt`] ("type context") struct offers a method
for each defined query. For example, to invoke the `type_of`
Expand All @@ -55,7 +55,7 @@ let ty = tcx.type_of(some_def_id);

[`TyTcx`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.TyCtxt.html

### How the compiler executes a query
## How the compiler executes a query

So you may be wondering what happens when you invoke a query
method. The answer is that, for each query, the compiler maintains a
Expand All @@ -64,7 +64,7 @@ simple: we clone the return value out of the cache and return it
(therefore, you should try to ensure that the return types of queries
are cheaply cloneable; insert an `Rc` if necessary).

#### Providers
### Providers

If, however, the query is *not* in the cache, then the compiler will
try to find a suitable **provider**. A provider is a function that has
Expand Down Expand Up @@ -97,7 +97,7 @@ fn provider<'tcx>(
Providers take two arguments: the `tcx` and the query key.
They return the result of the query.

#### How providers are setup
### How providers are setup

When the tcx is created, it is given the providers by its creator using
the [`Providers`][providers_struct] struct. This struct is generated by
Expand Down Expand Up @@ -164,7 +164,7 @@ they define both a `provide` and a `provide_extern` function, through
[rustc_metadata]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_metadata/index.html
[wasm_import_module_map]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_codegen_ssa/back/symbol_export/fn.wasm_import_module_map.html

### Adding a new query
## Adding a new query

How do you add a new query?
Defining a query takes place in two steps:
Expand Down Expand Up @@ -238,7 +238,7 @@ which is used to cheaply modify MIR in place. See the definition
of `Steal` for more details. New uses of `Steal` should **not** be
added without alerting `@rust-lang/compiler`.

#### Query structs and descriptions
### Query structs and descriptions

For each query, the `rustc_queries` macro will generate a "query struct"
named after the query. This struct is a kind of placeholder
Expand Down Expand Up @@ -294,7 +294,7 @@ rustc_queries! {

`rustc_queries` macro will generate an appropriate `impl` automatically.

## External Links
## External links

Related design ideas, and tracking issues:

Expand Down