Slight edits from lcnr's review

Author: jackh726

linkcheck.sh

@@ -0,0 +1,127 @@
+#!/bin/sh
+#
+# This is a script that can be used in each book's CI to validate links using
+# the same tool as rust-lang/rust.
+#
+# This requires the rust-docs rustup component to be installed in the nightly
+# toolchain.
+#
+# Usage:
+#   ./linkcheck.sh <name-of-book>
+#
+# Options:
+#
+# -i        "Iterative" mode. The script will not clean up after it is done so
+#           you can inspect the result, and re-run more quickly.
+#
+# --all     Check all books. This can help make sure you don't break links
+#           from other books into your book.
+#
+# --path <book-path>
+#           Path to the root directory for the book. Default to the current
+#           working directory if omitted.
+
+set -e
+
+html_dir="$(rustc +nightly --print sysroot)/share/doc/rust/html"
+
+if [ ! -d "$html_dir" ]
+then
+    echo "HTML docs are missing from sysroot: $html_dir"
+    echo "Make sure the nightly rust-docs rustup component is installed."
+    exit 1
+fi
+
+# Avoid failure caused by newer mdbook.
+export MDBOOK_OUTPUT__HTML__INPUT_404=""
+
+book_name=""
+# Default to the current directory
+book_path="."
+# Iterative will avoid cleaning up, so you can quickly run it repeatedly.
+iterative=0
+# If "1", test all books, else only this book.
+all_books=0
+
+while [ "$1" != "" ]
+do
+    case "$1" in
+        -i)
+            iterative=1
+            ;;
+        --all)
+            all_books=1
+            ;;
+        --path)
+            book_path="${2:-.}"
+            shift
+            ;;
+        *)
+            if [ -n "$book_name" ]
+            then
+                echo "only one argument allowed"
+                exit 1
+            fi
+            book_name="$1"
+            ;;
+    esac
+    shift
+done
+
+if [ -z "$book_name" ]
+then
+    echo "usage: $0 <name-of-book>"
+    exit 1
+fi
+
+if [ ! -f "$book_path/book.toml" ] && [ ! -f "$book_path/src/SUMMARY.md" ]
+then
+    echo "Run command in root directory of the book or provide a path to the book"
+    exit 1
+fi
+
+if [ ! -d "$html_dir/$book_name" ]
+then
+    echo "book name \"$book_name\" not found in sysroot \"$html_dir\""
+    exit 1
+fi
+
+if [ "$iterative" = "0" ]
+then
+    echo "Cleaning old directories..."
+    rm -rf linkcheck linkchecker
+fi
+
+if [ ! -e "linkchecker/main.rs" ] || [ "$iterative" = "0" ]
+then
+    echo "Downloading linkchecker source..."
+    nightly_hash=$(rustc +nightly -Vv | grep commit-hash | cut -f2 -d" ")
+    url="https://raw.githubusercontent.com/rust-lang/rust"
+    mkdir linkchecker
+    curl -o linkchecker/Cargo.lock ${url}/${nightly_hash}/Cargo.lock
+    curl -o linkchecker/Cargo.toml ${url}/${nightly_hash}/src/tools/linkchecker/Cargo.toml
+    curl -o linkchecker/main.rs ${url}/${nightly_hash}/src/tools/linkchecker/main.rs
+fi
+
+echo "Building book \"$book_name\"..."
+mdbook build "$book_path"
+
+cp -R "$html_dir" linkcheck
+rm -rf "linkcheck/$book_name"
+cp -R "$book_path/book" "linkcheck/$book_name"
+
+if [ "$all_books" = "1" ]
+then
+    check_path="linkcheck"
+else
+    check_path="linkcheck/$book_name"
+fi
+echo "Running linkchecker on \"$check_path\"..."
+cargo run --release --manifest-path=linkchecker/Cargo.toml -- "$check_path"
+
+if [ "$iterative" = "0" ]
+then
+    rm -rf linkcheck linkchecker
+fi
+
+echo "Link check completed successfully!"

src/divergence.md

@@ -18,11 +18,14 @@ The following language constructs unconditonally produce a _diverging expression
 * [A `continue` expression](./expressions/loop-expr.md#r-expr.loop.continue.type)
 * [A `return` expression](./expressions/return-expr.md#r-expr.return.type)
 * [A `match` expression with no arms](./expressions/match-expr.md#r-expr.match.type.diverging.empty)
-* [A `block` expression that it itself is diverging.](../expressions/block-expr.md#r-expr.block.type.diverging)
+* [A `block` expression that it itself is diverging.](./expressions/block-expr.md#r-expr.block.type.diverging)
 
 r[divergence.diverging-expressions.conditional]
 In a control flow expression, if all arms diverge, then the entire expression also diverges.
 
+r[divergence.diverging-expressions.place-expressions]
+A place expression of the type [`!`](./types/never.md) is considering _diverging_ only if it is read from.
+
 r[divergence.fallback]
 ## Fallback
 If a type to be inferred is only unified with diverging expressions, then that type will be inferred to be `!`.

src/expressions/block-expr.md

@@ -61,7 +61,7 @@ assert_eq!(5, five);
 ```
 
 r[expr.block.type.diverging]
-However, if there are any values unconditionally created within a block that are [diverging](../divergence.md), then the block itself is considered diverging.
+A block is itself considered to be [diverging](../divergence.md) if all reachable control flow paths contain a [diverging expression](../divergence.md#r-divergence.diverging-expressions).
 
 r[expr.block.value]
 Blocks are always [value expressions] and evaluate the last operand in value expression context.

src/expressions/match-expr.md

@@ -97,7 +97,7 @@ r[expr.match.binding-restriction]
 Every binding of the same name must have the same type, and have the same binding mode.
 
 r[expr.match.type]
-The type of the overall `match` expression is the least upper bound of the individual match arms.
+The type of the overall `match` expression is the [least upper bound](../type-coercions.md#r-coerce.least-upper-bound) of the individual match arms.
 
 r[expr.match.type.diverging.empty]
 If there are no match arms, then the `match` expression is diverging and the type is [`!`](../types/never.md).