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Go patch committed: Better error message for send as value
- From: Ian Lance Taylor <iant at google dot com>
- To: gcc-patches at gcc dot gnu dot org, gofrontend-dev at googlegroups dot com
- Date: Mon, 28 Mar 2011 15:49:12 -0700
- Subject: Go patch committed: Better error message for send as value
This patch to gccgo makes it emit better a error message when using the
now obsolete syntax of a send expression as a value. Bootstrapped and
ran Go testsuite on x86_64-unknown-linux-gnu. Committed to mainline.
Ian
diff -r 60aecfe6ad83 go/parse.cc
--- a/go/parse.cc Mon Mar 28 14:49:45 2011 -0700
+++ b/go/parse.cc Mon Mar 28 15:39:25 2011 -0700
@@ -3153,7 +3153,7 @@
case KEYWORD_MAP:
case KEYWORD_STRUCT:
case KEYWORD_INTERFACE:
- this->simple_stat(true, false, NULL, NULL);
+ this->simple_stat(true, NULL, NULL, NULL);
break;
case KEYWORD_GO:
case KEYWORD_DEFER:
@@ -3206,7 +3206,7 @@
this->unget_token(Token::make_identifier_token(identifier,
is_exported,
location));
- this->simple_stat(true, false, NULL, NULL);
+ this->simple_stat(true, NULL, NULL, NULL);
}
}
break;
@@ -3221,14 +3221,14 @@
location);
}
else if (!token->is_op(OPERATOR_SEMICOLON))
- this->simple_stat(true, false, NULL, NULL);
+ this->simple_stat(true, NULL, NULL, NULL);
break;
case Token::TOKEN_STRING:
case Token::TOKEN_INTEGER:
case Token::TOKEN_FLOAT:
case Token::TOKEN_IMAGINARY:
- this->simple_stat(true, false, NULL, NULL);
+ this->simple_stat(true, NULL, NULL, NULL);
break;
default:
@@ -3330,10 +3330,12 @@
// EmptyStmt was handled in Parse::statement.
// In order to make this work for if and switch statements, if
-// RETURN_EXP is true, and we see an ExpressionStat, we return the
+// RETURN_EXP is not NULL, and we see an ExpressionStat, we return the
// expression rather than adding an expression statement to the
// current block. If we see something other than an ExpressionStat,
-// we add the statement and return NULL.
+// we add the statement, set *RETURN_EXP to true if we saw a send
+// statement, and return NULL. The handling of send statements is for
+// better error messages.
// If P_RANGE_CLAUSE is not NULL, then this will recognize a
// RangeClause.
@@ -3342,7 +3344,7 @@
// guard (var := expr.("type") using the literal keyword "type").
Expression*
-Parse::simple_stat(bool may_be_composite_lit, bool return_exp,
+Parse::simple_stat(bool may_be_composite_lit, bool* return_exp,
Range_clause* p_range_clause, Type_switch* p_type_switch)
{
const Token* token = this->peek_token();
@@ -3385,7 +3387,11 @@
}
token = this->peek_token();
if (token->is_op(OPERATOR_CHANOP))
- this->send_stmt(this->verify_not_sink(exp));
+ {
+ this->send_stmt(this->verify_not_sink(exp));
+ if (return_exp != NULL)
+ *return_exp = true;
+ }
else if (token->is_op(OPERATOR_PLUSPLUS)
|| token->is_op(OPERATOR_MINUSMINUS))
this->inc_dec_stat(this->verify_not_sink(exp));
@@ -3404,7 +3410,7 @@
|| token->is_op(OPERATOR_ANDEQ)
|| token->is_op(OPERATOR_BITCLEAREQ))
this->assignment(this->verify_not_sink(exp), p_range_clause);
- else if (return_exp)
+ else if (return_exp != NULL)
return this->verify_not_sink(exp);
else
this->expression_stat(this->verify_not_sink(exp));
@@ -3743,9 +3749,14 @@
this->gogo_->start_block(location);
+ bool saw_simple_stat = false;
Expression* cond = NULL;
+ bool saw_send_stmt;
if (this->simple_stat_may_start_here())
- cond = this->simple_stat(false, true, NULL, NULL);
+ {
+ cond = this->simple_stat(false, &saw_send_stmt, NULL, NULL);
+ saw_simple_stat = true;
+ }
if (cond != NULL && this->peek_token()->is_op(OPERATOR_SEMICOLON))
{
// The SimpleStat is an expression statement.
@@ -3756,7 +3767,20 @@
{
if (this->peek_token()->is_op(OPERATOR_SEMICOLON))
this->advance_token();
- cond = this->expression(PRECEDENCE_NORMAL, false, false, NULL);
+ else if (saw_simple_stat)
+ {
+ if (saw_send_stmt)
+ error_at(this->location(),
+ ("send statement used as value; "
+ "use select for non-blocking send"));
+ else
+ error_at(this->location(),
+ "expected %<;%> after statement in if expression");
+ if (!this->expression_may_start_here())
+ cond = Expression::make_error(this->location());
+ }
+ if (cond == NULL)
+ cond = this->expression(PRECEDENCE_NORMAL, false, false, NULL);
}
this->gogo_->start_block(this->location());
@@ -3809,10 +3833,16 @@
this->gogo_->start_block(location);
+ bool saw_simple_stat = false;
Expression* switch_val = NULL;
+ bool saw_send_stmt;
Type_switch type_switch;
if (this->simple_stat_may_start_here())
- switch_val = this->simple_stat(false, true, NULL, &type_switch);
+ {
+ switch_val = this->simple_stat(false, &saw_send_stmt, NULL,
+ &type_switch);
+ saw_simple_stat = true;
+ }
if (switch_val != NULL && this->peek_token()->is_op(OPERATOR_SEMICOLON))
{
// The SimpleStat is an expression statement.
@@ -3823,6 +3853,16 @@
{
if (this->peek_token()->is_op(OPERATOR_SEMICOLON))
this->advance_token();
+ else if (saw_simple_stat)
+ {
+ if (saw_send_stmt)
+ error_at(this->location(),
+ ("send statement used as value; "
+ "use select for non-blocking send"));
+ else
+ error_at(this->location(),
+ "expected %<;%> after statement in switch expression");
+ }
if (!this->peek_token()->is_op(OPERATOR_LCURLY))
{
if (this->peek_token()->is_identifier())
@@ -3840,7 +3880,7 @@
if (is_coloneq)
{
// This must be a TypeSwitchGuard.
- switch_val = this->simple_stat(false, true, NULL,
+ switch_val = this->simple_stat(false, &saw_send_stmt, NULL,
&type_switch);
if (!type_switch.found)
{
@@ -4500,11 +4540,19 @@
{
// We might be looking at a Condition, an InitStat, or a
// RangeClause.
- cond = this->simple_stat(false, true, &range_clause, NULL);
+ bool saw_send_stmt;
+ cond = this->simple_stat(false, &saw_send_stmt, &range_clause, NULL);
if (!this->peek_token()->is_op(OPERATOR_SEMICOLON))
{
if (cond == NULL && !range_clause.found)
- error_at(this->location(), "parse error in for statement");
+ {
+ if (saw_send_stmt)
+ error_at(this->location(),
+ ("send statement used as value; "
+ "use select for non-blocking send"));
+ else
+ error_at(this->location(), "parse error in for statement");
+ }
}
else
{
@@ -4608,7 +4656,7 @@
else
{
this->gogo_->start_block(this->location());
- this->simple_stat(false, false, NULL, NULL);
+ this->simple_stat(false, NULL, NULL, NULL);
*post = this->gogo_->finish_block(this->location());
}
}
@@ -4992,8 +5040,13 @@
token = this->advance_token();
else if (!token->is_eof() || !saw_errors())
{
- error_at(this->location(),
- "expected %<;%> or newline after top level declaration");
+ if (token->is_op(OPERATOR_CHANOP))
+ error_at(this->location(),
+ ("send statement used as value; "
+ "use select for non-blocking send"));
+ else
+ error_at(this->location(),
+ "expected %<;%> or newline after top level declaration");
this->skip_past_error(OPERATOR_INVALID);
}
}
diff -r 60aecfe6ad83 go/parse.h
--- a/go/parse.h Mon Mar 28 14:49:45 2011 -0700
+++ b/go/parse.h Mon Mar 28 15:39:25 2011 -0700
@@ -223,7 +223,7 @@
void statement(Label*);
bool statement_may_start_here();
void labeled_stmt(const std::string&, source_location);
- Expression* simple_stat(bool, bool, Range_clause*, Type_switch*);
+ Expression* simple_stat(bool, bool*, Range_clause*, Type_switch*);
bool simple_stat_may_start_here();
void statement_list();
bool statement_list_may_start_here();