134 lines
4.0 KiB
Rust
134 lines
4.0 KiB
Rust
use rustc_errors::{Applicability, DiagnosticBuilder};
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use rustc_ast::ptr::P;
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use rustc_ast::token::{self, TokenKind};
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use rustc_ast::tokenstream::{DelimSpan, TokenStream, TokenTree};
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use rustc_ast::{self as ast, *};
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use rustc_ast_pretty::pprust;
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use rustc_expand::base::*;
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use rustc_parse::parser::Parser;
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use rustc_span::symbol::{sym, Ident, Symbol};
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use rustc_span::{Span, DUMMY_SP};
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pub fn expand_assert<'cx>(
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cx: &'cx mut ExtCtxt<'_>,
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sp: Span,
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tts: TokenStream,
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) -> Box<dyn MacResult + 'cx> {
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let Assert { cond_expr, custom_message } = match parse_assert(cx, sp, tts) {
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Ok(assert) => assert,
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Err(mut err) => {
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err.emit();
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return DummyResult::any(sp);
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}
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};
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// `core::panic` and `std::panic` are different macros, so we use call-site
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// context to pick up whichever is currently in scope.
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let sp = cx.with_call_site_ctxt(sp);
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let tokens = custom_message.unwrap_or_else(|| {
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TokenStream::from(TokenTree::token(
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TokenKind::lit(
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token::Str,
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Symbol::intern(&format!(
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"assertion failed: {}",
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pprust::expr_to_string(&cond_expr).escape_debug()
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)),
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None,
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),
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DUMMY_SP,
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))
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});
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let args = P(MacArgs::Delimited(DelimSpan::from_single(sp), MacDelimiter::Parenthesis, tokens));
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let panic_call = MacCall {
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path: Path::from_ident(Ident::new(sym::panic, sp)),
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args,
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prior_type_ascription: None,
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};
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let if_expr = cx.expr_if(
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sp,
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cx.expr(sp, ExprKind::Unary(UnOp::Not, cond_expr)),
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cx.expr(sp, ExprKind::MacCall(panic_call)),
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None,
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);
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MacEager::expr(if_expr)
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}
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struct Assert {
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cond_expr: P<ast::Expr>,
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custom_message: Option<TokenStream>,
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}
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fn parse_assert<'a>(
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cx: &mut ExtCtxt<'a>,
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sp: Span,
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stream: TokenStream,
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) -> Result<Assert, DiagnosticBuilder<'a>> {
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let mut parser = cx.new_parser_from_tts(stream);
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if parser.token == token::Eof {
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let mut err = cx.struct_span_err(sp, "macro requires a boolean expression as an argument");
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err.span_label(sp, "boolean expression required");
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return Err(err);
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}
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let cond_expr = parser.parse_expr()?;
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// Some crates use the `assert!` macro in the following form (note extra semicolon):
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//
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// assert!(
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// my_function();
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// );
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//
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// Emit an error about semicolon and suggest removing it.
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if parser.token == token::Semi {
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let mut err = cx.struct_span_err(sp, "macro requires an expression as an argument");
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err.span_suggestion(
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parser.token.span,
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"try removing semicolon",
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String::new(),
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Applicability::MaybeIncorrect,
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);
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err.emit();
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parser.bump();
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}
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// Some crates use the `assert!` macro in the following form (note missing comma before
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// message):
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//
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// assert!(true "error message");
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//
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// Emit an error and suggest inserting a comma.
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let custom_message =
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if let token::Literal(token::Lit { kind: token::Str, .. }) = parser.token.kind {
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let mut err = cx.struct_span_err(parser.token.span, "unexpected string literal");
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let comma_span = parser.prev_token.span.shrink_to_hi();
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err.span_suggestion_short(
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comma_span,
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"try adding a comma",
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", ".to_string(),
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Applicability::MaybeIncorrect,
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);
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err.emit();
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parse_custom_message(&mut parser)
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} else if parser.eat(&token::Comma) {
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parse_custom_message(&mut parser)
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} else {
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None
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};
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if parser.token != token::Eof {
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parser.expect_one_of(&[], &[])?;
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unreachable!();
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}
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Ok(Assert { cond_expr, custom_message })
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}
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fn parse_custom_message(parser: &mut Parser<'_>) -> Option<TokenStream> {
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let ts = parser.parse_tokens();
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if !ts.is_empty() { Some(ts) } else { None }
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}
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