comment out FIXMEs to not display them on UI (#2186)

src/doc/rustc-dev-guide/src/method-lookup.md

@@ -67,6 +67,7 @@ imported to use an inherent method, they are associated with the type
 itself (note that inherent impls can only be defined in the same
 crate as the type itself).
 
+<!--
 FIXME: Inherent candidates are not always derived from impls.  If you
 have a trait object, such as a value of type `Box<ToString>`, then the
 trait methods (`to_string()`, in this case) are inherently associated
@@ -76,7 +77,8 @@ to change: when DST's "impl Trait for Trait" is complete, trait object
 dispatch could be subsumed into trait matching, and the type parameter
 behavior should be reconsidered in light of where clauses.
 
-TODO: Is this FIXME still accurate?
+Is this still accurate?
+-->
 
 **Extension candidates** are derived from imported traits.  If I have
 the trait `ToString` imported, and I call `to_string()` as a method,

src/doc/rustc-dev-guide/src/solve/normalization.md

@@ -1,5 +1,8 @@
 # Normalization in the new solver
 
+> **NOTE**: FIXME: The content of this chapter has some been changed quite
+significantly since it was written.
+
 With the new solver we've made some fairly significant changes to normalization when compared
 to the existing implementation.
 
@@ -52,12 +55,14 @@ before assigning the resulting rigid type to an inference variable. This is used
 This has to be used whenever we match on the value of some type, both inside
 and outside of the trait solver.
 
+<!--
 FIXME: structure, maybe we should have an "alias handling" chapter instead as
 talking about normalization without explaining that doesn't make too much
 sense.
 
 FIXME: it is likely that this will subtly change again by mostly moving structural
 normalization into `NormalizesTo`.
+-->
 
 [structural_norm]: https://github.com/rust-lang/rust/blob/2627e9f3012a97d3136b3e11bf6bd0853c38a534/compiler/rustc_trait_selection/src/solve/alias_relate.rs#L140-L175
 [structural-relate]: https://github.com/rust-lang/rust/blob/a0569fa8f91b5271e92d2f73fd252de7d3d05b9c/compiler/rustc_trait_selection/src/solve/alias_relate.rs#L88-L107
@@ -72,11 +77,13 @@ possible. However, this only works for aliases referencing bound variables if th
 not ambiguous as we're unable to replace the alias with a corresponding inference
 variable without leaking universes.
 
+<!--
 FIXME: we previously had to also be careful about instantiating the new inference
 variable with another normalizeable alias. Due to our recent changes to generalization,
 this should not be the case anymore. Equating an inference variable with an alias
 now always uses `AliasRelate` to fully normalize the alias before instantiating the
 inference variable: [source][generalize-no-alias]
+-->
 
 [generalize-no-alias]: https://github.com/rust-lang/rust/blob/a0569fa8f91b5271e92d2f73fd252de7d3d05b9c/compiler/rustc_infer/src/infer/relate/generalize.rs#L353-L358
 

src/doc/rustc-dev-guide/src/solve/opaque-types.md

@@ -60,6 +60,7 @@ Finally, we check whether the item bounds of the opaque hold for the expected ty
 [eq-prev]: https://github.com/rust-lang/rust/blob/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/compiler/rustc_trait_selection/src/solve/normalizes_to/opaque_types.rs#L51-L59
 [insert-storage]: https://github.com/rust-lang/rust/blob/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/compiler/rustc_trait_selection/src/solve/normalizes_to/opaque_types.rs#L68
 [item-bounds-ck]: https://github.com/rust-lang/rust/blob/384d26fc7e3bdd7687cc17b2662b091f6017ec2a/compiler/rustc_trait_selection/src/solve/normalizes_to/opaque_types.rs#L69-L74
+
 [^1]: FIXME: this should ideally only result in a unique candidate given that we require the args to be placeholders and regions are always inference vars
 [^2]: FIXME: why do we check whether the expected type is rigid for this.
 
@@ -101,6 +102,7 @@ The handling of member constraints does not change in the new solver. See the
 
 FIXME: We need to continue to support calling methods on still unconstrained
 opaque types in their defining scope. It's unclear how to best do this.
+
 ```rust
 use std::future::Future;
 use futures::FutureExt;

src/doc/rustc-dev-guide/src/tests/directives.md

@@ -2,7 +2,9 @@
 
 <!-- toc -->
 
-> **FIXME(jieyouxu)** completely revise this chapter.
+<!--
+FIXME(jieyouxu) completely revise this chapter.
+-->
 
 Directives are special comments that tell compiletest how to build and interpret
 a test. They must appear before the Rust source in the test. They may also
@@ -248,10 +250,11 @@ Consider writing the test as a proper incremental test instead.
 |-------------|--------------------------------------------------------------|------------------------------------------|---------------------------|
 | `doc-flags` | Flags passed to `rustdoc` when building the test or aux file | `rustdoc`, `js-doc-test`, `rustdoc-json` | Any valid `rustdoc` flags |
 
-> **FIXME(rustdoc)**: what does `check-test-line-numbers-match` do?
->
-> Asked in
-> <https://rust-lang.zulipchat.com/#narrow/stream/266220-t-rustdoc/topic/What.20is.20the.20.60check-test-line-numbers-match.60.20directive.3F>.
+<!--
+**FIXME(rustdoc)**: what does `check-test-line-numbers-match` do?
+Asked in
+<https://rust-lang.zulipchat.com/#narrow/stream/266220-t-rustdoc/topic/What.20is.20the.20.60check-test-line-numbers-match.60.20directive.3F>.
+-->
 
 ### Pretty printing