Change pp indent to signed to allow negative indents

Author: dtolnay

compiler/rustc_ast_pretty/src/pp.rs

@@ -392,7 +392,9 @@ impl Printer {
         if size > self.space {
             self.print_stack.push(PrintFrame::Broken { indent: self.indent, breaks: token.breaks });
             self.indent = match token.indent {
-                IndentStyle::Block { offset } => (self.indent as isize + offset) as usize,
+                IndentStyle::Block { offset } => {
+                    usize::try_from(self.indent as isize + offset).unwrap()
+                }
                 IndentStyle::Visual => (MARGIN - self.space) as usize,
             };
         } else {

compiler/rustc_ast_pretty/src/pp/convenience.rs

@@ -3,20 +3,17 @@ use std::borrow::Cow;
 
 impl Printer {
     /// "raw box"
-    pub fn rbox(&mut self, indent: usize, breaks: Breaks) {
-        self.scan_begin(BeginToken {
-            indent: IndentStyle::Block { offset: indent as isize },
-            breaks,
-        })
+    pub fn rbox(&mut self, indent: isize, breaks: Breaks) {
+        self.scan_begin(BeginToken { indent: IndentStyle::Block { offset: indent }, breaks })
     }
 
     /// Inconsistent breaking box
-    pub fn ibox(&mut self, indent: usize) {
+    pub fn ibox(&mut self, indent: isize) {
         self.rbox(indent, Breaks::Inconsistent)
     }
 
     /// Consistent breaking box
-    pub fn cbox(&mut self, indent: usize) {
+    pub fn cbox(&mut self, indent: isize) {
         self.rbox(indent, Breaks::Consistent)
     }
 

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -92,7 +92,7 @@ pub struct State<'a> {
     ann: &'a (dyn PpAnn + 'a),
 }
 
-crate const INDENT_UNIT: usize = 4;
+crate const INDENT_UNIT: isize = 4;
 
 /// Requires you to pass an input filename and reader so that
 /// it can scan the input text for comments to copy forward.

compiler/rustc_hir_pretty/src/lib.rs

@@ -139,7 +139,7 @@ impl<'a> PrintState<'a> for State<'a> {
     }
 }
 
-pub const INDENT_UNIT: usize = 4;
+pub const INDENT_UNIT: isize = 4;
 
 /// Requires you to pass an input filename and reader so that
 /// it can scan the input text for comments to copy forward.