chore(vendor): add anyhow crate

third_party/crates/syn-3.0.6/tests/common/visit.rs

@@ -0,0 +1,119 @@
+use proc_macro2::{Delimiter, Group, TokenStream, TokenTree};
+use std::mem;
+use syn::visit_mut::{self, VisitMut};
+use syn::{Expr, File, Generics, LifetimeParam, MacroDelimiter, Stmt, StmtMacro, TypeParam};
+
+pub struct FlattenParens {
+    discard_paren_attrs: bool,
+}
+
+impl FlattenParens {
+    pub fn discard_attrs() -> Self {
+        FlattenParens {
+            discard_paren_attrs: true,
+        }
+    }
+
+    pub fn combine_attrs() -> Self {
+        FlattenParens {
+            discard_paren_attrs: false,
+        }
+    }
+
+    pub fn visit_token_stream_mut(tokens: &mut TokenStream) {
+        *tokens = mem::take(tokens)
+            .into_iter()
+            .flat_map(|tt| {
+                if let TokenTree::Group(group) = tt {
+                    let delimiter = group.delimiter();
+                    let mut content = group.stream();
+                    Self::visit_token_stream_mut(&mut content);
+                    if let Delimiter::Parenthesis = delimiter {
+                        content
+                    } else {
+                        TokenStream::from(TokenTree::Group(Group::new(delimiter, content)))
+                    }
+                } else {
+                    TokenStream::from(tt)
+                }
+            })
+            .collect();
+    }
+}
+
+impl VisitMut for FlattenParens {
+    fn visit_expr_mut(&mut self, e: &mut Expr) {
+        while let Expr::Paren(paren) = e {
+            let paren_attrs = mem::take(&mut paren.attrs);
+            *e = mem::replace(&mut *paren.expr, Expr::PLACEHOLDER);
+            if !paren_attrs.is_empty() && !self.discard_paren_attrs {
+                let nested_attrs = match e {
+                    Expr::Assign(e) => &mut e.attrs,
+                    Expr::Binary(e) => &mut e.attrs,
+                    Expr::Cast(e) => &mut e.attrs,
+                    _ => unimplemented!(),
+                };
+                assert!(nested_attrs.is_empty());
+                *nested_attrs = paren_attrs;
+            }
+        }
+        visit_mut::visit_expr_mut(self, e);
+    }
+}
+
+pub struct AsIfPrinted;
+
+impl VisitMut for AsIfPrinted {
+    fn visit_file_mut(&mut self, file: &mut File) {
+        file.shebang = None;
+        visit_mut::visit_file_mut(self, file);
+    }
+
+    fn visit_generics_mut(&mut self, generics: &mut Generics) {
+        if generics.params.is_empty() {
+            generics.lt_token = None;
+            generics.gt_token = None;
+        }
+        if let Some(where_clause) = &generics.where_clause {
+            if where_clause.predicates.is_empty() {
+                generics.where_clause = None;
+            }
+        }
+        visit_mut::visit_generics_mut(self, generics);
+    }
+
+    fn visit_lifetime_param_mut(&mut self, param: &mut LifetimeParam) {
+        if param.bounds.is_empty() {
+            param.colon_token = None;
+        }
+        visit_mut::visit_lifetime_param_mut(self, param);
+    }
+
+    fn visit_stmt_mut(&mut self, stmt: &mut Stmt) {
+        if let Stmt::Expr(expr, semi) = stmt {
+            if let Expr::Macro(e) = expr {
+                if match e.mac.delimiter {
+                    MacroDelimiter::Brace(_) => true,
+                    MacroDelimiter::Paren(_) | MacroDelimiter::Bracket(_) => semi.is_some(),
+                } {
+                    let Expr::Macro(expr) = mem::replace(expr, Expr::PLACEHOLDER) else {
+                        unreachable!();
+                    };
+                    *stmt = Stmt::Macro(StmtMacro {
+                        attrs: expr.attrs,
+                        mac: expr.mac,
+                        semi_token: *semi,
+                    });
+                }
+            }
+        }
+        visit_mut::visit_stmt_mut(self, stmt);
+    }
+
+    fn visit_type_param_mut(&mut self, param: &mut TypeParam) {
+        if param.bounds.is_empty() {
+            param.colon_token = None;
+        }
+        visit_mut::visit_type_param_mut(self, param);
+    }
+}