mv compiler to compiler/

compiler/rustc_builtin_macros/src/deriving/debug.rs

@@ -0,0 +1,137 @@
+use crate::deriving::generic::ty::*;
+use crate::deriving::generic::*;
+use crate::deriving::path_std;
+
+use rustc_ast::ptr::P;
+use rustc_ast::{self as ast, Expr, MetaItem};
+use rustc_expand::base::{Annotatable, ExtCtxt};
+use rustc_span::symbol::{sym, Ident};
+use rustc_span::{Span, DUMMY_SP};
+
+pub fn expand_deriving_debug(
+    cx: &mut ExtCtxt<'_>,
+    span: Span,
+    mitem: &MetaItem,
+    item: &Annotatable,
+    push: &mut dyn FnMut(Annotatable),
+) {
+    // &mut ::std::fmt::Formatter
+    let fmtr =
+        Ptr(Box::new(Literal(path_std!(fmt::Formatter))), Borrowed(None, ast::Mutability::Mut));
+
+    let trait_def = TraitDef {
+        span,
+        attributes: Vec::new(),
+        path: path_std!(fmt::Debug),
+        additional_bounds: Vec::new(),
+        generics: Bounds::empty(),
+        is_unsafe: false,
+        supports_unions: false,
+        methods: vec![MethodDef {
+            name: sym::fmt,
+            generics: Bounds::empty(),
+            explicit_self: borrowed_explicit_self(),
+            args: vec![(fmtr, sym::f)],
+            ret_ty: Literal(path_std!(fmt::Result)),
+            attributes: Vec::new(),
+            is_unsafe: false,
+            unify_fieldless_variants: false,
+            combine_substructure: combine_substructure(Box::new(|a, b, c| {
+                show_substructure(a, b, c)
+            })),
+        }],
+        associated_types: Vec::new(),
+    };
+    trait_def.expand(cx, mitem, item, push)
+}
+
+/// We use the debug builders to do the heavy lifting here
+fn show_substructure(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) -> P<Expr> {
+    // build fmt.debug_struct(<name>).field(<fieldname>, &<fieldval>)....build()
+    // or fmt.debug_tuple(<name>).field(&<fieldval>)....build()
+    // based on the "shape".
+    let (ident, vdata, fields) = match substr.fields {
+        Struct(vdata, fields) => (substr.type_ident, *vdata, fields),
+        EnumMatching(_, _, v, fields) => (v.ident, &v.data, fields),
+        EnumNonMatchingCollapsed(..) | StaticStruct(..) | StaticEnum(..) => {
+            cx.span_bug(span, "nonsensical .fields in `#[derive(Debug)]`")
+        }
+    };
+
+    // We want to make sure we have the ctxt set so that we can use unstable methods
+    let span = cx.with_def_site_ctxt(span);
+    let name = cx.expr_lit(span, ast::LitKind::Str(ident.name, ast::StrStyle::Cooked));
+    let builder = Ident::new(sym::debug_trait_builder, span);
+    let builder_expr = cx.expr_ident(span, builder);
+
+    let fmt = substr.nonself_args[0].clone();
+
+    let mut stmts = vec![];
+    match vdata {
+        ast::VariantData::Tuple(..) | ast::VariantData::Unit(..) => {
+            // tuple struct/"normal" variant
+            let expr =
+                cx.expr_method_call(span, fmt, Ident::new(sym::debug_tuple, span), vec![name]);
+            stmts.push(cx.stmt_let(span, true, builder, expr));
+
+            for field in fields {
+                // Use double indirection to make sure this works for unsized types
+                let field = cx.expr_addr_of(field.span, field.self_.clone());
+                let field = cx.expr_addr_of(field.span, field);
+
+                let expr = cx.expr_method_call(
+                    span,
+                    builder_expr.clone(),
+                    Ident::new(sym::field, span),
+                    vec![field],
+                );
+
+                // Use `let _ = expr;` to avoid triggering the
+                // unused_results lint.
+                stmts.push(stmt_let_underscore(cx, span, expr));
+            }
+        }
+        ast::VariantData::Struct(..) => {
+            // normal struct/struct variant
+            let expr =
+                cx.expr_method_call(span, fmt, Ident::new(sym::debug_struct, span), vec![name]);
+            stmts.push(cx.stmt_let(DUMMY_SP, true, builder, expr));
+
+            for field in fields {
+                let name = cx.expr_lit(
+                    field.span,
+                    ast::LitKind::Str(field.name.unwrap().name, ast::StrStyle::Cooked),
+                );
+
+                // Use double indirection to make sure this works for unsized types
+                let field = cx.expr_addr_of(field.span, field.self_.clone());
+                let field = cx.expr_addr_of(field.span, field);
+                let expr = cx.expr_method_call(
+                    span,
+                    builder_expr.clone(),
+                    Ident::new(sym::field, span),
+                    vec![name, field],
+                );
+                stmts.push(stmt_let_underscore(cx, span, expr));
+            }
+        }
+    }
+
+    let expr = cx.expr_method_call(span, builder_expr, Ident::new(sym::finish, span), vec![]);
+
+    stmts.push(cx.stmt_expr(expr));
+    let block = cx.block(span, stmts);
+    cx.expr_block(block)
+}
+
+fn stmt_let_underscore(cx: &mut ExtCtxt<'_>, sp: Span, expr: P<ast::Expr>) -> ast::Stmt {
+    let local = P(ast::Local {
+        pat: cx.pat_wild(sp),
+        ty: None,
+        init: Some(expr),
+        id: ast::DUMMY_NODE_ID,
+        span: sp,
+        attrs: ast::AttrVec::new(),
+    });
+    ast::Stmt { id: ast::DUMMY_NODE_ID, kind: ast::StmtKind::Local(local), span: sp }
+}