Suggest correct path in include_bytes!

Author: kornelski

compiler/rustc_builtin_macros/src/source_util.rs

@@ -3,18 +3,19 @@ use rustc_ast::ptr::P;
 use rustc_ast::token;
 use rustc_ast::tokenstream::TokenStream;
 use rustc_ast_pretty::pprust;
+use rustc_data_structures::sync::Lrc;
 use rustc_expand::base::{
-    check_zero_tts, get_single_str_from_tts, parse_expr, resolve_path, DummyResult, ExtCtxt,
-    MacEager, MacResult,
+    check_zero_tts, get_single_str_from_tts, get_single_str_spanned_from_tts, parse_expr,
+    resolve_path, DummyResult, ExtCtxt, MacEager, MacResult,
 };
 use rustc_expand::module::DirOwnership;
 use rustc_parse::new_parser_from_file;
 use rustc_parse::parser::{ForceCollect, Parser};
 use rustc_session::lint::builtin::INCOMPLETE_INCLUDE;
 use rustc_span::symbol::Symbol;
 use rustc_span::{Pos, Span};
-
 use smallvec::SmallVec;
+use std::path::Path;
 use std::rc::Rc;
 
 // These macros all relate to the file system; they either return
@@ -180,32 +181,22 @@ pub fn expand_include_str(
     tts: TokenStream,
 ) -> Box<dyn MacResult + 'static> {
     let sp = cx.with_def_site_ctxt(sp);
-    let file = match get_single_str_from_tts(cx, sp, tts, "include_str!") {
-        Ok(file) => file,
+    let (path, path_span) = match get_single_str_spanned_from_tts(cx, sp, tts, "include_str!") {
+        Ok(res) => res,
         Err(guar) => return DummyResult::any(sp, guar),
     };
-    let file = match resolve_path(&cx.sess, file.as_str(), sp) {
-        Ok(f) => f,
-        Err(err) => {
-            let guar = err.emit();
-            return DummyResult::any(sp, guar);
-        }
-    };
-    match cx.source_map().load_binary_file(&file) {
+    match load_binary_file(cx, path.as_str(), sp, path_span) {
         Ok(bytes) => match std::str::from_utf8(&bytes) {
             Ok(src) => {
                 let interned_src = Symbol::intern(src);
                 MacEager::expr(cx.expr_str(sp, interned_src))
             }
             Err(_) => {
-                let guar = cx.dcx().span_err(sp, format!("{} wasn't a utf-8 file", file.display()));
+                let guar = cx.dcx().span_err(sp, format!("{path} wasn't a utf-8 file"));
                 DummyResult::any(sp, guar)
             }
         },
-        Err(e) => {
-            let guar = cx.dcx().span_err(sp, format!("couldn't read {}: {}", file.display(), e));
-            DummyResult::any(sp, guar)
-        }
+        Err(dummy) => dummy,
     }
 }
 
@@ -215,25 +206,57 @@ pub fn expand_include_bytes(
     tts: TokenStream,
 ) -> Box<dyn MacResult + 'static> {
     let sp = cx.with_def_site_ctxt(sp);
-    let file = match get_single_str_from_tts(cx, sp, tts, "include_bytes!") {
-        Ok(file) => file,
+    let (path, path_span) = match get_single_str_spanned_from_tts(cx, sp, tts, "include_bytes!") {
+        Ok(res) => res,
         Err(guar) => return DummyResult::any(sp, guar),
     };
-    let file = match resolve_path(&cx.sess, file.as_str(), sp) {
-        Ok(f) => f,
-        Err(err) => {
-            let guar = err.emit();
-            return DummyResult::any(sp, guar);
-        }
-    };
-    match cx.source_map().load_binary_file(&file) {
+    match load_binary_file(cx, path.as_str(), sp, path_span) {
         Ok(bytes) => {
             let expr = cx.expr(sp, ast::ExprKind::IncludedBytes(bytes));
             MacEager::expr(expr)
         }
-        Err(e) => {
-            let guar = cx.dcx().span_err(sp, format!("couldn't read {}: {}", file.display(), e));
-            DummyResult::any(sp, guar)
+        Err(dummy) => dummy,
+    }
+}
+
+fn load_binary_file(
+    cx: &mut ExtCtxt<'_>,
+    original_path: &str,
+    macro_span: Span,
+    path_span: Span,
+) -> Result<Lrc<[u8]>, Box<dyn MacResult>> {
+    let resolved_path = match resolve_path(&cx.sess, original_path, macro_span) {
+        Ok(path) => path,
+        Err(err) => {
+            let guar = err.emit();
+            return Err(DummyResult::any(macro_span, guar));
+        }
+    };
+    match cx.source_map().load_binary_file(&resolved_path) {
+        Ok(data) => Ok(data),
+        Err(io_err) => {
+            let mut err = cx.dcx().struct_span_err(
+                macro_span,
+                format!("couldn't read {}: {io_err}", resolved_path.display()),
+            );
+            if Path::new(original_path).is_relative() {
+                for prefix in ["..", "../.."] {
+                    let parent_path = Path::new(prefix).join(original_path);
+                    if resolve_path(&cx.sess, &parent_path, macro_span)
+                        .map_or(false, |p| p.exists())
+                    {
+                        err.span_suggestion(
+                            path_span,
+                            "it's in a parent directory",
+                            format!("\"{}\"", parent_path.display().to_string().escape_debug()),
+                            rustc_lint_defs::Applicability::MachineApplicable,
+                        );
+                        break;
+                    }
+                }
+            }
+            let guar = err.emit();
+            Err(DummyResult::any(macro_span, guar))
         }
     }
 }

compiler/rustc_expand/src/base.rs

@@ -1338,6 +1338,15 @@ pub fn get_single_str_from_tts(
     tts: TokenStream,
     name: &str,
 ) -> Result<Symbol, ErrorGuaranteed> {
+    get_single_str_spanned_from_tts(cx, span, tts, name).map(|(s, _)| s)
+}
+
+pub fn get_single_str_spanned_from_tts(
+    cx: &mut ExtCtxt<'_>,
+    span: Span,
+    tts: TokenStream,
+    name: &str,
+) -> Result<(Symbol, Span), ErrorGuaranteed> {
     let mut p = cx.new_parser_from_tts(tts);
     if p.token == token::Eof {
         let guar = cx.dcx().emit_err(errors::OnlyOneArgument { span, name });
@@ -1349,7 +1358,12 @@ pub fn get_single_str_from_tts(
     if p.token != token::Eof {
         cx.dcx().emit_err(errors::OnlyOneArgument { span, name });
     }
-    expr_to_string(cx, ret, "argument must be a string literal").map(|(s, _)| s)
+    expr_to_spanned_string(cx, ret, "argument must be a string literal")
+        .map_err(|err| match err {
+            Ok((err, _)) => err.emit(),
+            Err(guar) => guar,
+        })
+        .map(|(symbol, _style, span)| (symbol, span))
 }
 
 /// Extracts comma-separated expressions from `tts`.

tests/ui/include-macros/parent_dir.rs

@@ -0,0 +1,4 @@
+fn main() {
+    let _ = include_str!("include-macros/file.txt");    //~ ERROR coudln't read
+                                                        //~^HELP parent directory
+}

tests/ui/include-macros/parent_dir.stderr

@@ -0,0 +1,12 @@
+error: couldn't read $DIR/include-macros/file.txt: No such file or directory (os error 2)
+  --> $DIR/parent_dir.rs:2:13
+   |
+LL |     let _ = include_str!("include-macros/file.txt");
+   |             ^^^^^^^^^^^^^-------------------------^
+   |                          |
+   |                          help: it's in a parent directory: `"../include-macros/file.txt"`
+   |
+   = note: this error originates in the macro `include_str` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 1 previous error
+