Rollup merge of #82269 - LeSeulArtichaut:cleanup-ppmode, r=spastorino

Cleanup `PpMode` and friends

This PR:
 - Separates `PpSourceMode` and `PpHirMode` to remove invalid states
 - Renames the variant to remove the redundant `Ppm` prefix
 - Adds basic documentation for the different pretty-print modes
 - Cleanups some code to make it more idiomatic

Not sure if this is actually useful, but it looks cleaner to me.

compiler/rustc_session/src/config.rs

@@ -2057,40 +2057,21 @@ fn parse_pretty(
     debugging_opts: &DebuggingOptions,
     efmt: ErrorOutputType,
 ) -> Option<PpMode> {
-    let pretty = if debugging_opts.unstable_options {
-        matches.opt_default("pretty", "normal").map(|a| {
-            // stable pretty-print variants only
-            parse_pretty_inner(efmt, &a, false)
-        })
-    } else {
-        None
-    };
-
-    return if pretty.is_none() {
-        debugging_opts.unpretty.as_ref().map(|a| {
-            // extended with unstable pretty-print variants
-            parse_pretty_inner(efmt, &a, true)
-        })
-    } else {
-        pretty
-    };
-
     fn parse_pretty_inner(efmt: ErrorOutputType, name: &str, extended: bool) -> PpMode {
         use PpMode::*;
-        use PpSourceMode::*;
         let first = match (name, extended) {
-            ("normal", _) => PpmSource(PpmNormal),
-            ("identified", _) => PpmSource(PpmIdentified),
-            ("everybody_loops", true) => PpmSource(PpmEveryBodyLoops),
-            ("expanded", _) => PpmSource(PpmExpanded),
-            ("expanded,identified", _) => PpmSource(PpmExpandedIdentified),
-            ("expanded,hygiene", _) => PpmSource(PpmExpandedHygiene),
-            ("hir", true) => PpmHir(PpmNormal),
-            ("hir,identified", true) => PpmHir(PpmIdentified),
-            ("hir,typed", true) => PpmHir(PpmTyped),
-            ("hir-tree", true) => PpmHirTree(PpmNormal),
-            ("mir", true) => PpmMir,
-            ("mir-cfg", true) => PpmMirCFG,
+            ("normal", _) => Source(PpSourceMode::Normal),
+            ("identified", _) => Source(PpSourceMode::Identified),
+            ("everybody_loops", true) => Source(PpSourceMode::EveryBodyLoops),
+            ("expanded", _) => Source(PpSourceMode::Expanded),
+            ("expanded,identified", _) => Source(PpSourceMode::ExpandedIdentified),
+            ("expanded,hygiene", _) => Source(PpSourceMode::ExpandedHygiene),
+            ("hir", true) => Hir(PpHirMode::Normal),
+            ("hir,identified", true) => Hir(PpHirMode::Identified),
+            ("hir,typed", true) => Hir(PpHirMode::Typed),
+            ("hir-tree", true) => HirTree,
+            ("mir", true) => Mir,
+            ("mir-cfg", true) => MirCFG,
             _ => {
                 if extended {
                     early_error(
@@ -2119,6 +2100,18 @@ fn parse_pretty(
         tracing::debug!("got unpretty option: {:?}", first);
         first
     }
+
+    if debugging_opts.unstable_options {
+        if let Some(a) = matches.opt_default("pretty", "normal") {
+            // stable pretty-print variants only
+            return Some(parse_pretty_inner(efmt, &a, false));
+        }
+    }
+
+    debugging_opts.unpretty.as_ref().map(|a| {
+        // extended with unstable pretty-print variants
+        parse_pretty_inner(efmt, &a, true)
+    })
 }
 
 pub fn make_crate_type_option() -> RustcOptGroup {
@@ -2226,22 +2219,43 @@ impl fmt::Display for CrateType {
 
 #[derive(Copy, Clone, PartialEq, Debug)]
 pub enum PpSourceMode {
-    PpmNormal,
-    PpmEveryBodyLoops,
-    PpmExpanded,
-    PpmIdentified,
-    PpmExpandedIdentified,
-    PpmExpandedHygiene,
-    PpmTyped,
+    /// `--pretty=normal`
+    Normal,
+    /// `-Zunpretty=everybody_loops`
+    EveryBodyLoops,
+    /// `--pretty=expanded`
+    Expanded,
+    /// `--pretty=identified`
+    Identified,
+    /// `--pretty=expanded,identified`
+    ExpandedIdentified,
+    /// `--pretty=expanded,hygiene`
+    ExpandedHygiene,
+}
+
+#[derive(Copy, Clone, PartialEq, Debug)]
+pub enum PpHirMode {
+    /// `-Zunpretty=hir`
+    Normal,
+    /// `-Zunpretty=hir,identified`
+    Identified,
+    /// `-Zunpretty=hir,typed`
+    Typed,
 }
 
 #[derive(Copy, Clone, PartialEq, Debug)]
 pub enum PpMode {
-    PpmSource(PpSourceMode),
-    PpmHir(PpSourceMode),
-    PpmHirTree(PpSourceMode),
-    PpmMir,
-    PpmMirCFG,
+    /// Options that print the source code, i.e.
+    /// `--pretty` and `-Zunpretty=everybody_loops`
+    Source(PpSourceMode),
+    /// Options that print the HIR, i.e. `-Zunpretty=hir`
+    Hir(PpHirMode),
+    /// `-Zunpretty=hir-tree`
+    HirTree,
+    /// `-Zunpretty=mir`
+    Mir,
+    /// `-Zunpretty=mir-cfg`
+    MirCFG,
 }
 
 impl PpMode {
@@ -2249,22 +2263,19 @@ impl PpMode {
         use PpMode::*;
         use PpSourceMode::*;
         match *self {
-            PpmSource(PpmNormal | PpmIdentified) => false,
+            Source(Normal | Identified) => false,
 
-            PpmSource(
-                PpmExpanded | PpmEveryBodyLoops | PpmExpandedIdentified | PpmExpandedHygiene,
-            )
-            | PpmHir(_)
-            | PpmHirTree(_)
-            | PpmMir
-            | PpmMirCFG => true,
-            PpmSource(PpmTyped) => panic!("invalid state"),
+            Source(Expanded | EveryBodyLoops | ExpandedIdentified | ExpandedHygiene)
+            | Hir(_)
+            | HirTree
+            | Mir
+            | MirCFG => true,
         }
     }
 
     pub fn needs_analysis(&self) -> bool {
         use PpMode::*;
-        matches!(*self, PpmMir | PpmMirCFG)
+        matches!(*self, Mir | MirCFG)
     }
 }