I enabled code coverage and ran the gdb test suite, and noticed that
the new Rust parser was missing testing on a few lines that were easy
to cover. This patch mostly adds tests for certain syntax errors; but
this process also uncovered a couple of real bugs: I must have
cut-and-pasted the 'sizeof' parsing code from some other code, because
it is checking for KW_MUT (the old bison parser did not do this), and
the array length check is actually impossible because a negative
number like '-1' is parsed as two tokens.
gdb/ChangeLog
2021-04-22 Tom Tromey <tom@tromey.com>
* rust-parse.c (rust_parser::parse_sizeof): Remove KW_MUT code.
(struct typed_val_int) <val>: Now ULONGEST.
(rust_parser::parse_array_type): Remove negative check.
(rust_lex_int_test): Change 'value' to ULONGEST.
gdb/testsuite/ChangeLog
2021-04-22 Tom Tromey <tom@tromey.com>
* gdb.rust/modules.exp: Add checks for syntax errors.
* gdb.rust/expr.exp: Add checks for syntax errors.
* gdb.rust/simple.exp: Add checks for syntax errors.
The Rust expression parser was written to construct its own AST, then
lower this to GDB expressions. I did this primarily because the old
expressions were difficult to work with; after rewriting those, I
realized I could remove the AST from the Rust parser.
After looking at this, I realized it might be simpler to rewrite the
parser. This patch reimplements it as a recursive-descent parser. I
kept a fair amount of the existing code -- the lexer is pulled in
nearly unchanged.
There are several benefits to this approach:
* The parser is shorter now (from 2882 LOC to 2351).
* The parser is just ordinary C++ code that can be debugged in the
usual way.
* Memory management in the parser is now straightforward, as
parsing methods simply return a unique pointer or vector.
This required a couple of minor changes to the test suite, as some
errors have changed.
While this passes the tests, it's possible there are lurking bugs,
particularly around error handling.
gdb/ChangeLog
2021-04-16 Tom Tromey <tom@tromey.com>
* rust-parse.c: New file.
* rust-exp.y: Remove.
* Makefile.in (COMMON_SFILES): Add rust-parse.c.
(SFILES): Remove rust-exp.y.
(YYFILES, local-maintainer-clean): Remove rust-exp.c.
gdb/testsuite/ChangeLog
2021-04-16 Tom Tromey <tom@tromey.com>
* gdb.rust/simple.exp: Change error text.
* gdb.rust/expr.exp: Change error text.