From b3a27d2f97aa3e21237036e50b54bbe94d19d048 Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Fri, 23 Jun 2023 06:38:55 -0600 Subject: [PATCH] Implement Ada target name symbol Ada 2022 adds the "target name symbol", which can be used on the right hand side of an assignment to refer to the left hand side. This allows for convenient updates. This patch implements this for gdb's Ada expression parser. Reviewed-By: Eli Zaretskii --- gdb/NEWS | 3 ++ gdb/ada-exp.h | 60 ++++++++++++++++++++++++++++++ gdb/ada-exp.y | 41 ++++++++++++++++---- gdb/ada-lang.c | 1 + gdb/testsuite/gdb.ada/assign_1.exp | 15 ++++++++ 5 files changed, 113 insertions(+), 7 deletions(-) diff --git a/gdb/NEWS b/gdb/NEWS index ac5dc424d3f..4c91a380e6c 100644 --- a/gdb/NEWS +++ b/gdb/NEWS @@ -86,6 +86,9 @@ * The Ada 2022 Enum_Rep and Enum_Val attributes are now supported. +* The Ada 2022 target name symbol ('@') is now supported by the Ada + expression parser. + * The 'list' command now accepts '.' as an argument, which tells GDB to print the location where the inferior is stopped. If the inferior hasn't started yet, the command will print around the main function. diff --git a/gdb/ada-exp.h b/gdb/ada-exp.h index dc34a43bdd6..c66c9a1b4c9 100644 --- a/gdb/ada-exp.h +++ b/gdb/ada-exp.h @@ -553,6 +553,66 @@ public: enum exp_opcode opcode () const override { return BINOP_ASSIGN; } + + value *current () + { return m_current; } + + /* A helper function for the parser to evaluate just the LHS of the + assignment. */ + value *eval_for_resolution (struct expression *exp) + { + return std::get<0> (m_storage)->evaluate (nullptr, exp, + EVAL_AVOID_SIDE_EFFECTS); + } + + /* The parser must construct the assignment node before parsing the + RHS, so that '@' can access the assignment, so this helper + function is needed to set the RHS after construction. */ + void set_rhs (operation_up rhs) + { + std::get<1> (m_storage) = std::move (rhs); + } + +private: + + /* Temporary storage for the value of the left-hand-side. */ + value *m_current = nullptr; +}; + +/* Implement the Ada target name symbol ('@'). This is used to refer + to the LHS of an assignment from the RHS. */ +class ada_target_operation : public operation +{ +public: + + explicit ada_target_operation (ada_assign_operation *lhs) + : m_lhs (lhs) + { } + + value *evaluate (struct type *expect_type, + struct expression *exp, + enum noside noside) override + { + if (noside == EVAL_AVOID_SIDE_EFFECTS) + return m_lhs->eval_for_resolution (exp); + return m_lhs->current (); + } + + enum exp_opcode opcode () const override + { + /* It doesn't really matter. */ + return OP_VAR_VALUE; + } + + void dump (struct ui_file *stream, int depth) const override + { + gdb_printf (stream, _("%*sAda target symbol '@'\n"), depth, ""); + } + +private: + + /* The left hand side of the assignment. */ + ada_assign_operation *m_lhs; }; /* This abstract class represents a single component in an Ada diff --git a/gdb/ada-exp.y b/gdb/ada-exp.y index 019ac85211e..3280a483a5e 100644 --- a/gdb/ada-exp.y +++ b/gdb/ada-exp.y @@ -415,6 +415,13 @@ make_tick_completer (struct stoken tok) (new ada_tick_completer (std::string (tok.ptr, tok.length)))); } +/* A convenience typedef. */ +typedef std::unique_ptr ada_assign_up; + +/* The stack of currently active assignment expressions. This is used + to implement '@', the target name symbol. */ +static std::vector assignments; + %} %union @@ -492,17 +499,25 @@ start : exp1 exp1 : exp | exp1 ';' exp { ada_wrap2 (BINOP_COMMA); } - | primary ASSIGN exp /* Extension for convenience */ + | primary ASSIGN + { + assignments.emplace_back + (new ada_assign_operation (ada_pop (), nullptr)); + } + exp /* Extension for convenience */ { + ada_assign_up assign + = std::move (assignments.back ()); + assignments.pop_back (); + value *lhs_val = (assign->eval_for_resolution + (pstate->expout.get ())); + operation_up rhs = pstate->pop (); - operation_up lhs = ada_pop (); - value *lhs_val - = lhs->evaluate (nullptr, pstate->expout.get (), - EVAL_AVOID_SIDE_EFFECTS); rhs = resolve (std::move (rhs), true, lhs_val->type ()); - pstate->push_new - (std::move (lhs), std::move (rhs)); + + assign->set_rhs (std::move (rhs)); + pstate->push (std::move (assign)); } ; @@ -602,6 +617,17 @@ primary : aggregate } ; +primary : '@' + { + if (assignments.empty ()) + error (_("the target name symbol ('@') may only " + "appear in an assignment context")); + ada_assign_operation *current + = assignments.back ().get (); + pstate->push_new (current); + } + ; + simple_exp : primary ; @@ -1170,6 +1196,7 @@ ada_parse (struct parser_state *par_state) components.clear (); associations.clear (); int_storage.clear (); + assignments.clear (); int result = yyparse (); if (!result) diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c index caeea58a803..1261ee8fa05 100644 --- a/gdb/ada-lang.c +++ b/gdb/ada-lang.c @@ -9661,6 +9661,7 @@ ada_assign_operation::evaluate (struct type *expect_type, enum noside noside) { value *arg1 = std::get<0> (m_storage)->evaluate (nullptr, exp, noside); + scoped_restore save_lhs = make_scoped_restore (&m_current, arg1); ada_aggregate_operation *ag_op = dynamic_cast (std::get<1> (m_storage).get ()); diff --git a/gdb/testsuite/gdb.ada/assign_1.exp b/gdb/testsuite/gdb.ada/assign_1.exp index d5d81281e46..8349f5379fd 100644 --- a/gdb/testsuite/gdb.ada/assign_1.exp +++ b/gdb/testsuite/gdb.ada/assign_1.exp @@ -29,3 +29,18 @@ gdb_test "print \$xxx := 1" \ "set convenience variable \$xxx to 1" +gdb_test "print \$xxx := @ + 23 + @" \ + " = 25" \ + "update convenience using '@'" + +gdb_test "print \$yyy := 1" " = 1" "set yyy" + +gdb_test "print \$xxx := @ + (\$yyy := 1 + @)" \ + " = 27" \ + "nested assignment" + +gdb_test "print \$yyy" " = 2" "value of yyy after nested assignment" + +gdb_test "print 23 + @" \ + "may only appear in an assignment context" \ + "invalid use of '@' causes error" -- 2.30.2