Module rustc_expand::base[][src]



Fill-in macro expansion result, to allow compilation to continue after hitting errors.

One of these is made during expansion and incrementally updated as we go; when a macro expansion occurs, the resulting nodes have the backtrace() -> expn_data of their expansion context stored into their span.

Error type that denotes indeterminacy.

MacResult implementation for the common case where you’ve already built each form of AST that you might return.

A struct representing a macro definition in “lowered” form ready for expansion.


Result of an expansion that may need to be retried. Consider using this for non-MultiItemModifier expanders as well.

The kind of macro invocation or definition.

A syntax extension kind.


The result of a macro expansion. The return values of the various methods are spliced into the AST at the callsite of the macro.

Represents a thing that maps token trees to Macro Results


Non-fatally assert that tts is empty. Note that this function returns even when tts is non-empty, macros that need to stop compilation should call cx.parse_sess.span_diagnostic.abort_if_errors() (this should be done as rarely as possible).

Extracts a string literal from the macro expanded version of expr, returning a diagnostic error of err_msg if expr is not a string literal. The returned bool indicates whether an applicable suggestion has already been added to the diagnostic to avoid emitting multiple suggestions. Err(None) indicates that an ast error was encountered.

Extracts a string literal from the macro expanded version of expr, emitting err_msg if expr is not a string literal. This does not stop compilation on error, merely emits a non-fatal error and returns None.

Extracts comma-separated expressions from tts. On error, emit it, and return None.

Interpreting tts as a comma-separated sequence of expressions, expect exactly one string literal, or emit an error and return None.

Parse an expression. On error, emit it, advancing to Eof, and return None.

This nonterminal looks like some specific enums from proc-macro-hack and procedural-masquerade crates. We need to maintain some special pretty-printing behavior for them due to incorrect asserts in old versions of those crates and their wide use in the ecosystem. See issue #73345 for more details. FIXME(#73933): Remove this eventually.

Type Definitions