ci: use some tricks to format macro bodies

.git-blame-ignore-revs

@@ -0,0 +1,2 @@
+# Format macro bodies
+a0c7f8017b964a2de8bc3aabebdabd4a8f2c0905

ci/style.rs

@@ -97,7 +97,10 @@ enum State {
 
 fn check_style(file: &str, path: &Path, err: &mut Errors) {
     let mut state = State::Start;
-    let mut s_macros = 0;
+
+    // FIXME: see below
+    // let mut s_macros = 0;
+
     let mut f_macros = 0;
     let mut in_impl = false;
 
@@ -140,7 +143,8 @@ fn check_style(file: &str, path: &Path, err: &mut Errors) {
         } else if line.starts_with("type ") && !in_impl {
             State::Typedefs
         } else if line.starts_with("s! {") {
-            s_macros += 1;
+            // FIXME: see below
+            // s_macros += 1;
             State::Structs
         } else if line.starts_with("s_no_extra_traits! {") {
             // multiple macros of this type are allowed
@@ -175,10 +179,13 @@ fn check_style(file: &str, path: &Path, err: &mut Errors) {
             f_macros += 1;
             err.error(path, i, "multiple f! macros in one module");
         }
-        if s_macros == 2 {
-            s_macros += 1;
-            err.error(path, i, "multiple s! macros in one module");
-        }
+
+        // FIXME(#4109): multiple should be allowed if at least one is `cfg(not) within `cfg_if`.
+        // For now just disable this and check by hand.
+        // if s_macros == 2 {
+        //     s_macros += 1;
+        //     err.error(path, i, "multiple s! macros in one module");
+        // }
 
         state = line_state;
     }

ci/style.sh

@@ -2,13 +2,64 @@
 
 set -eux
 
+if [ -n "${CI:-}" ]; then
+    rustup toolchain install nightly -c rustfmt --allow-downgrade
+    rustup override set nightly
+
+    check="--check"
+fi
+
 rustc ci/style.rs && ./style src
 
-rustup toolchain install nightly -c rustfmt --allow-downgrade
-rustup override set nightly
 command -v rustfmt
 rustfmt -V
-cargo fmt --all -- --check
+
+# Save a list of all source files
+tmpfile="file-list~" # trailing tilde for gitignore
+find src -name '*.rs' > "$tmpfile"
+
+# Before formatting, replace all macro identifiers with a function signature.
+# This allows `rustfmt` to format it.
+while IFS= read -r file; do
+    if [ "$file" = "src/macros.rs" ]; then
+        # Too much special syntax in `macros.rs` that we don't want to format
+        continue
+    fi
+
+    # Turn all braced macro `foo! { /* ... */ }` invocations into
+    # `fn foo_fmt_tmp() { /* ... */ }`.
+    perl -pi -e 's/(?!macro_rules)\b(\w+)!\s*\{/fn $1_fmt_tmp() {/g' "$file"
+
+    # Replace `if #[cfg(...)]` within `cfg_if` with `if cfg_tmp!([...])` which
+    # `rustfmt` will format. We put brackets within the parens so it is easy to
+    # match (trying to match parentheses would catch the first closing `)` which
+    # wouldn't be correct for something like `all(any(...), ...)`).
+    perl -pi -0777 -e 's/if #\[cfg\((.*?)\)\]/if cfg_tmp!([$1])/gms' "$file"
+
+    # We have some instances of `{const}` that make macros happy but aren't
+    # valid syntax. Replace this with just the keyword, plus an indicator
+    # comment on the preceding line (which is where rustfmt puts it. Also
+    # rust-lang/rustfmt#5464).
+    perl -pi -e 's/^(\s*)(.*)\{const\}/$1\/\* FMT-CONST \*\/\n$1$2const/g' "$file"
+
+    # Format the file. We need to invoke `rustfmt` directly since `cargo fmt`
+    # can't figure out the module tree with the hacks in place.
+    failed=false
+    rustfmt --config-path rustfmt.toml "$file" ${check:+"$check"} || failed=true
+
+    # Restore all changes to the files.
+    perl -pi -e 's/fn (\w+)_fmt_tmp\(\)/$1!/g' "$file"
+    perl -pi -0777 -e 's/cfg_tmp!\(\[(.*?)\]\)/#[cfg($1)]/gms' "$file"
+    perl -pi -0777 -e 's/\/\* FMT-CONST \*\/(?:\n\s*)?(.*?)const/$1\{const\}/gms' "$file"
+
+    # Defer emitting the failure until after the files get reset
+    if [ "$failed" != "false" ]; then
+        echo "Formatting failed"
+        exit 1
+    fi
+done < "$tmpfile"
+
+rm "$tmpfile"
 
 if shellcheck --version ; then
     find . -name '*.sh' -print0 | xargs -0 shellcheck

rustfmt.toml

@@ -1 +1,2 @@
 error_on_line_overflow = true
+edition = "2021"

src/fixed_width_ints.rs

@@ -20,7 +20,16 @@ pub type uint32_t = u32;
 pub type uint64_t = u64;
 
 cfg_if! {
-    if #[cfg(all(target_arch = "aarch64", not(any(target_os = "windows", target_os = "macos", target_os = "ios", target_os = "tvos", target_os = "watchos"))))] {
+    if #[cfg(all(
+        target_arch = "aarch64",
+        not(any(
+            target_os = "windows",
+            target_os = "macos",
+            target_os = "ios",
+            target_os = "tvos",
+            target_os = "watchos"
+        ))
+    ))] {
         // This introduces partial support for FFI with __int128 and
         // equivalent types on platforms where Rust's definition is validated
         // to match the standard C ABI of that platform.
@@ -93,7 +102,15 @@ cfg_if! {
 
         // static_assert_eq!(core::mem::size_of::<__uint128_t>(), _SIZE_128);
         // static_assert_eq!(core::mem::align_of::<__uint128_t>(), _ALIGN_128);
-    } else if #[cfg(all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios", target_os = "tvos", target_os = "watchos")))] {
+    } else if #[cfg(all(
+        target_arch = "aarch64",
+        any(
+            target_os = "macos",
+            target_os = "ios",
+            target_os = "tvos",
+            target_os = "watchos"
+        )
+    ))] {
         /// C `__int128_t`
         pub type __int128_t = i128;
         /// C `__uint128_t`