make panictry! private to libsyntax

This commit completely removes usage of the `panictry!` macro from outside libsyntax. The macro causes parse errors to be fatal, so using it in libsyntax_ext caused parse failures *within* a syntax extension to be fatal, which is probably not intended. Furthermore, this commit adds spans to diagnostics emitted by empty extensions if they were missing, à la #56491.
rust-lang · Mark-Simulacrum · Dec 24, 2018 · Dec 24, 2018 · Dec 27, 2018 · Dec 27, 2018
commit 0a6fb8473872b2a6dd7fe66697f90dceac667ec4
diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
@@ -23,7 +23,7 @@ use syntax::json::JsonEmitter;
 use syntax::ptr::P;
 use syntax::symbol::keywords;
 use syntax_pos::DUMMY_SP;
-use errors;
+use errors::{self, FatalError};
 use errors::emitter::{Emitter, EmitterWriter};
 use parking_lot::ReentrantMutex;
 
@@ -429,7 +429,13 @@ pub fn run_core(options: RustdocOptions) -> (clean::Crate, RenderInfo, RenderOpt
 
         let control = &driver::CompileController::basic();
 
-        let krate = panictry!(driver::phase_1_parse_input(control, &sess, &input));
+        let krate = match driver::phase_1_parse_input(control, &sess, &input) {
+            Ok(krate) => krate,
+            Err(mut e) => {
+                e.emit();
+                FatalError.raise();
+            }
+        };
 
         let name = match crate_name {
             Some(ref crate_name) => crate_name.clone(),

diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
@@ -32,7 +32,7 @@ extern crate rustc_metadata;
 extern crate rustc_target;
 extern crate rustc_typeck;
 extern crate serialize;
-#[macro_use] extern crate syntax;
+extern crate syntax;
 extern crate syntax_pos;
 extern crate test as testing;
 #[macro_use] extern crate log;

diff --git a/src/librustdoc/test.rs b/src/librustdoc/test.rs
@@ -1,4 +1,4 @@
-use errors;
+use errors::{self, FatalError};
 use errors::emitter::ColorConfig;
 use rustc_data_structures::sync::Lrc;
 use rustc_lint;
@@ -84,9 +84,14 @@ pub fn run(mut options: Options) -> isize {
         target_features::add_configuration(&mut cfg, &sess, &*codegen_backend);
         sess.parse_sess.config = cfg;
 
-        let krate = panictry!(driver::phase_1_parse_input(&driver::CompileController::basic(),
-                                                        &sess,
-                                                        &input));
+        let krate =
+            match driver::phase_1_parse_input(&driver::CompileController::basic(), &sess, &input) {
+                Ok(krate) => krate,
+                Err(mut e) => {
+                    e.emit();
+                    FatalError.raise();
+                }
+            };
         let driver::ExpansionResult { defs, mut hir_forest, .. } = {
             phase_2_configure_and_expand(
                 &sess,

diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
@@ -44,8 +44,6 @@ use ast::AttrId;
 // way towards a non-panic!-prone parser. It should be used for fatal parsing
 // errors; eventually we plan to convert all code using panictry to just use
 // normal try.
-// Exported for syntax_ext, not meant for general use.
-#[macro_export]
 macro_rules! panictry {
     ($e:expr) => ({
         use std::result::Result::{Ok, Err};

diff --git a/src/libsyntax_ext/asm.rs b/src/libsyntax_ext/asm.rs
@@ -4,6 +4,7 @@ use self::State::*;
 
 use rustc_data_structures::thin_vec::ThinVec;
 
+use errors::DiagnosticBuilder;
 use syntax::ast;
 use syntax::ext::base;
 use syntax::ext::base::*;
@@ -51,6 +52,34 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt,
                                        feature_gate::EXPLAIN_ASM);
     }
 
+    let mut inline_asm = match parse_inline_asm(cx, sp, tts) {
+        Ok(Some(inline_asm)) => inline_asm,
+        Ok(None) => return DummyResult::expr(sp),
+        Err(mut err) => {
+            err.emit();
+            return DummyResult::expr(sp);
+        }
+    };
+
+    // If there are no outputs, the inline assembly is executed just for its side effects,
+    // so ensure that it is volatile
+    if inline_asm.outputs.is_empty() {
+        inline_asm.volatile = true;
+    }
+
+    MacEager::expr(P(ast::Expr {
+        id: ast::DUMMY_NODE_ID,
+        node: ast::ExprKind::InlineAsm(P(inline_asm)),
+        span: sp,
+        attrs: ThinVec::new(),
+    }))
+}
+
+fn parse_inline_asm<'a>(
+    cx: &mut ExtCtxt<'a>,
+    sp: Span,
+    tts: &[tokenstream::TokenTree],
+) -> Result<Option<ast::InlineAsm>, DiagnosticBuilder<'a>> {
     // Split the tts before the first colon, to avoid `asm!("x": y)`  being
     // parsed as `asm!(z)` with `z = "x": y` which is type ascription.
     let first_colon = tts.iter()
@@ -80,22 +109,33 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt,
                 if asm_str_style.is_some() {
                     // If we already have a string with instructions,
                     // ending up in Asm state again is an error.
-                    span_err!(cx, sp, E0660, "malformed inline assembly");
-                    return DummyResult::expr(sp);
+                    return Err(struct_span_err!(
+                        cx.parse_sess.span_diagnostic,
+                        sp,
+                        E0660,
+                        "malformed inline assembly"
+                    ));
                 }
                 // Nested parser, stop before the first colon (see above).
                 let mut p2 = cx.new_parser_from_tts(&tts[..first_colon]);
-                let (s, style) = match expr_to_string(cx,
-                                                      panictry!(p2.parse_expr()),
-                                                      "inline assembly must be a string literal") {
-                    Some((s, st)) => (s, st),
-                    // let compilation continue
-                    None => return DummyResult::expr(sp),
-                };
+
+                if p2.token == token::Eof {
+                    let mut err =
+                        cx.struct_span_err(sp, "macro requires a string literal as an argument");
+                    err.span_label(sp, "string literal required");
+                    return Err(err);
+                }
+
+                let expr = p2.parse_expr()?;
+                let (s, style) =
+                    match expr_to_string(cx, expr, "inline assembly must be a string literal") {
+                        Some((s, st)) => (s, st),
+                        None => return Ok(None),
+                    };
 
                 // This is most likely malformed.
                 if p2.token != token::Eof {
-                    let mut extra_tts = panictry!(p2.parse_all_token_trees());
+                    let mut extra_tts = p2.parse_all_token_trees()?;
                     extra_tts.extend(tts[first_colon..].iter().cloned());
                     p = parse::stream_to_parser(cx.parse_sess, extra_tts.into_iter().collect());
                 }
@@ -105,18 +145,17 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt,
             }
             Outputs => {
                 while p.token != token::Eof && p.token != token::Colon && p.token != token::ModSep {
-
                     if !outputs.is_empty() {
                         p.eat(&token::Comma);
                     }
 
-                    let (constraint, _str_style) = panictry!(p.parse_str());
+                    let (constraint, _) = p.parse_str()?;
 
                     let span = p.prev_span;
 
-                    panictry!(p.expect(&token::OpenDelim(token::Paren)));
-                    let out = panictry!(p.parse_expr());
-                    panictry!(p.expect(&token::CloseDelim(token::Paren)));
+                    p.expect(&token::OpenDelim(token::Paren))?;
+                    let expr = p.parse_expr()?;
+                    p.expect(&token::CloseDelim(token::Paren))?;
 
                     // Expands a read+write operand into two operands.
                     //
@@ -143,20 +182,19 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt,
                     let is_indirect = constraint_str.contains("*");
                     outputs.push(ast::InlineAsmOutput {
                         constraint: output.unwrap_or(constraint),
-                        expr: out,
+                        expr,
                         is_rw,
                         is_indirect,
                     });
                 }
             }
             Inputs => {
                 while p.token != token::Eof && p.token != token::Colon && p.token != token::ModSep {
-
                     if !inputs.is_empty() {
                         p.eat(&token::Comma);
                     }
 
-                    let (constraint, _str_style) = panictry!(p.parse_str());
+                    let (constraint, _) = p.parse_str()?;
 
                     if constraint.as_str().starts_with("=") {
                         span_err!(cx, p.prev_span, E0662,
@@ -166,21 +204,20 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt,
                                                 "input operand constraint contains '+'");
                     }
 
-                    panictry!(p.expect(&token::OpenDelim(token::Paren)));
-                    let input = panictry!(p.parse_expr());
-                    panictry!(p.expect(&token::CloseDelim(token::Paren)));
+                    p.expect(&token::OpenDelim(token::Paren))?;
+                    let input = p.parse_expr()?;
+                    p.expect(&token::CloseDelim(token::Paren))?;
 
                     inputs.push((constraint, input));
                 }
             }
             Clobbers => {
                 while p.token != token::Eof && p.token != token::Colon && p.token != token::ModSep {
-
                     if !clobs.is_empty() {
                         p.eat(&token::Comma);
                     }
 
-                    let (s, _str_style) = panictry!(p.parse_str());
+                    let (s, _) = p.parse_str()?;
 
                     if OPTIONS.iter().any(|&opt| s == opt) {
                         cx.span_warn(p.prev_span, "expected a clobber, found an option");
@@ -193,7 +230,7 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt,
                 }
             }
             Options => {
-                let (option, _str_style) = panictry!(p.parse_str());
+                let (option, _) = p.parse_str()?;
 
                 if option == "volatile" {
                     // Indicates that the inline assembly has side effects
@@ -234,26 +271,15 @@ pub fn expand_asm<'cx>(cx: &'cx mut ExtCtxt,
         }
     }
 
-    // If there are no outputs, the inline assembly is executed just for its side effects,
-    // so ensure that it is volatile
-    if outputs.is_empty() {
-        volatile = true;
-    }
-
-    MacEager::expr(P(ast::Expr {
-        id: ast::DUMMY_NODE_ID,
-        node: ast::ExprKind::InlineAsm(P(ast::InlineAsm {
-            asm,
-            asm_str_style: asm_str_style.unwrap(),
-            outputs,
-            inputs,
-            clobbers: clobs,
-            volatile,
-            alignstack,
-            dialect,
-            ctxt: cx.backtrace(),
-        })),
-        span: sp,
-        attrs: ThinVec::new(),
+    Ok(Some(ast::InlineAsm {
+        asm,
+        asm_str_style: asm_str_style.unwrap(),
+        outputs,
+        inputs,
+        clobbers: clobs,
+        volatile,
+        alignstack,
+        dialect,
+        ctxt: cx.backtrace(),
     }))
 }
diff --git a/src/libsyntax_ext/assert.rs b/src/libsyntax_ext/assert.rs
@@ -1,9 +1,11 @@
-use syntax::ast::*;
+use errors::DiagnosticBuilder;
+use syntax::ast::{self, *};
 use syntax::source_map::Spanned;
 use syntax::ext::base::*;
 use syntax::ext::build::AstBuilder;
 use syntax::parse::token;
 use syntax::print::pprust;
+use syntax::ptr::P;
 use syntax::symbol::Symbol;
 use syntax::tokenstream::{TokenStream, TokenTree};
 use syntax_pos::{Span, DUMMY_SP};
@@ -13,33 +15,18 @@ pub fn expand_assert<'cx>(
     sp: Span,
     tts: &[TokenTree],
 ) -> Box<dyn MacResult + 'cx> {
-    let mut parser = cx.new_parser_from_tts(tts);
-
-    if parser.token == token::Eof {
-        cx.struct_span_err(sp, "macro requires a boolean expression as an argument")
-            .span_label(sp, "boolean expression required")
-            .emit();
-        return DummyResult::expr(sp);
-    }
-
-    let cond_expr = panictry!(parser.parse_expr());
-    let custom_msg_args = if parser.eat(&token::Comma) {
-        let ts = parser.parse_tokens();
-        if !ts.is_empty() {
-            Some(ts)
-        } else {
-            None
+    let Assert { cond_expr, custom_message } = match parse_assert(cx, sp, tts) {
+        Ok(assert) => assert,
+        Err(mut err) => {
+            err.emit();
+            return DummyResult::expr(sp);
         }
-    } else {
-        None
     };
 
     let sp = sp.apply_mark(cx.current_expansion.mark);
     let panic_call = Mac_ {
         path: Path::from_ident(Ident::new(Symbol::intern("panic"), sp)),
-        tts: if let Some(ts) = custom_msg_args {
-            ts.into()
-        } else {
+        tts: custom_message.unwrap_or_else(|| {
             TokenStream::from(TokenTree::Token(
                 DUMMY_SP,
                 token::Literal(
@@ -49,8 +36,8 @@ pub fn expand_assert<'cx>(
                     ))),
                     None,
                 ),
-            )).into()
-        },
+            ))
+        }).into(),
         delim: MacDelimiter::Parenthesis,
     };
     let if_expr = cx.expr_if(
@@ -67,3 +54,36 @@ pub fn expand_assert<'cx>(
     );
     MacEager::expr(if_expr)
 }
+
+struct Assert {
+    cond_expr: P<ast::Expr>,
+    custom_message: Option<TokenStream>,
+}
+
+fn parse_assert<'a>(
+    cx: &mut ExtCtxt<'a>,
+    sp: Span,
+    tts: &[TokenTree]
+) -> Result<Assert, DiagnosticBuilder<'a>> {
+    let mut parser = cx.new_parser_from_tts(tts);
+
+    if parser.token == token::Eof {
+        let mut err = cx.struct_span_err(sp, "macro requires a boolean expression as an argument");
+        err.span_label(sp, "boolean expression required");
+        return Err(err);
+    }
+
+    Ok(Assert {
+        cond_expr: parser.parse_expr()?,
+        custom_message: if parser.eat(&token::Comma) {
+            let ts = parser.parse_tokens();
+            if !ts.is_empty() {
+                Some(ts)
+            } else {
+                None
+            }
+        } else {
+            None
+        },
+    })
+}