fix internal warnings on syntax errors

2007-08-30  Juerg Billeter  <j@bitron.ch>

	* vala/parser.y: fix internal warnings on syntax errors

svn path=/trunk/; revision=544

diff --git a/ChangeLog b/ChangeLog
index e8f94725ea06227efa2e407d48a49306b4293a22..1583b507e2f2a930812d2f3e68ac486408ce159d 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2007-08-30  Jürg Billeter  <j@bitron.ch>
+
+       * vala/parser.y: fix internal warnings on syntax errors
+
 2007-08-30  Jürg Billeter  <j@bitron.ch>
 
        * vala/valasemanticanalyzer.vala: improve error reporting for

diff --git a/vala/parser.y b/vala/parser.y
index bd6a2b89a8d643254ce706cecd0c3b2ab8e14fc8..f672a19510e8205a71c458d2cf65232b094a5d14 100644 (file)
--- a/vala/parser.y
+++ b/vala/parser.y
@@ -721,9 +721,14 @@ parenthesized_expression
        : OPEN_PARENS expression CLOSE_PARENS
          {
                ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_parenthesized_expression_new ($2, src));
-               g_object_unref (src);
-               g_object_unref ($2);
+               if ($2 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       $$ = VALA_EXPRESSION (vala_parenthesized_expression_new ($2, src));
+                       g_object_unref (src);
+                       g_object_unref ($2);
+               }
          }
        ;
 
@@ -855,73 +860,118 @@ object_creation_expression
 sizeof_expression
        : SIZEOF open_parens type_name CLOSE_PARENS
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_sizeof_expression_new ($3, src));
-               g_object_unref ($3);
-               g_object_unref (src);
+               if ($3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_sizeof_expression_new ($3, src));
+                       g_object_unref ($3);
+                       g_object_unref (src);
+               }
          }
 
 typeof_expression
        : TYPEOF open_parens type_name CLOSE_PARENS
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_typeof_expression_new ($3, src));
-               g_object_unref ($3);
-               g_object_unref (src);
+               if ($3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_typeof_expression_new ($3, src));
+                       g_object_unref ($3);
+                       g_object_unref (src);
+               }
          }
 
 unary_expression
        : primary_expression
        | PLUS unary_expression
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_PLUS, $2, src));
-               g_object_unref (src);
-               g_object_unref ($2);
+               if ($2 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_PLUS, $2, src));
+                       g_object_unref (src);
+                       g_object_unref ($2);
+               }
          }
        | MINUS unary_expression
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_MINUS, $2, src));
-               g_object_unref (src);
-               g_object_unref ($2);
+               if ($2 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_MINUS, $2, src));
+                       g_object_unref (src);
+                       g_object_unref ($2);
+               }
          }
        | OP_NEG unary_expression
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_LOGICAL_NEGATION, $2, src));
-               g_object_unref (src);
-               g_object_unref ($2);
+               if ($2 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_LOGICAL_NEGATION, $2, src));
+                       g_object_unref (src);
+                       g_object_unref ($2);
+               }
          }
        | TILDE unary_expression
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_BITWISE_COMPLEMENT, $2, src));
-               g_object_unref (src);
-               g_object_unref ($2);
+               if ($2 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_BITWISE_COMPLEMENT, $2, src));
+                       g_object_unref (src);
+                       g_object_unref ($2);
+               }
          }
        | pre_increment_expression
        | pre_decrement_expression
        | REF unary_expression
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_REF, $2, src));
-               g_object_unref (src);
-               g_object_unref ($2);
+               if ($2 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_REF, $2, src));
+                       g_object_unref (src);
+                       g_object_unref ($2);
+               }
          }
        | OUT unary_expression
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_OUT, $2, src));
-               g_object_unref (src);
-               g_object_unref ($2);
+               if ($2 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_OUT, $2, src));
+                       g_object_unref (src);
+                       g_object_unref ($2);
+               }
          }
        | HASH unary_expression
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_reference_transfer_expression_new ($2, src));
-               g_object_unref (src);
-               g_object_unref ($2);
+               if ($2 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_reference_transfer_expression_new ($2, src));
+                       g_object_unref (src);
+                       g_object_unref ($2);
+               }
          }
        | cast_expression
        | pointer_indirection_expression
@@ -931,51 +981,76 @@ unary_expression
 pre_increment_expression
        : OP_INC unary_expression
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_INCREMENT, $2, src));
-               g_object_unref ($2);
-               g_object_unref (src);
+               if ($2 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_INCREMENT, $2, src));
+                       g_object_unref ($2);
+                       g_object_unref (src);
+               }
          }
        ;
 
 pre_decrement_expression
        : OP_DEC unary_expression
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_DECREMENT, $2, src));
-               g_object_unref ($2);
-               g_object_unref (src);
+               if ($2 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_unary_expression_new (VALA_UNARY_OPERATOR_DECREMENT, $2, src));
+                       g_object_unref ($2);
+                       g_object_unref (src);
+               }
          }
        ;
 
 cast_expression
        : OPEN_CAST_PARENS type CLOSE_PARENS unary_expression
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_cast_expression_new ($4, $2, src, FALSE));
-               g_object_unref (src);
-               g_object_unref ($2);
-               g_object_unref ($4);
+               if ($2 == NULL || $4 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_cast_expression_new ($4, $2, src, FALSE));
+                       g_object_unref (src);
+                       g_object_unref ($2);
+                       g_object_unref ($4);
+               }
          }
        ;
 
 pointer_indirection_expression
        : STAR unary_expression
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_pointer_indirection_new ($2, src));
-               g_object_unref (src);
-               g_object_unref ($2);
+               if ($2 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_pointer_indirection_new ($2, src));
+                       g_object_unref (src);
+                       g_object_unref ($2);
+               }
          }
        ;
 
 addressof_expression
        : BITWISE_AND unary_expression
          {
-               ValaSourceReference *src = src(@1);
-               $$ = VALA_EXPRESSION (vala_addressof_expression_new ($2, src));
-               g_object_unref (src);
-               g_object_unref ($2);
+               if ($2 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@1);
+                       $$ = VALA_EXPRESSION (vala_addressof_expression_new ($2, src));
+                       g_object_unref (src);
+                       g_object_unref ($2);
+               }
          }
        ;
 
@@ -983,27 +1058,42 @@ multiplicative_expression
        : unary_expression
        | multiplicative_expression STAR unary_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_MUL, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_MUL, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        | multiplicative_expression DIV unary_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_DIV, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_DIV, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        | multiplicative_expression PERCENT unary_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_MOD, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_MOD, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        ;
 
@@ -1011,19 +1101,29 @@ additive_expression
        : multiplicative_expression
        | additive_expression PLUS multiplicative_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_PLUS, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_PLUS, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        | additive_expression MINUS multiplicative_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_MINUS, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_MINUS, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        ;
 
@@ -1031,21 +1131,31 @@ shift_expression
        : additive_expression
        | shift_expression OP_SHIFT_LEFT additive_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_SHIFT_LEFT, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_SHIFT_LEFT, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        /* don't use two OP_GT to resolve parse conflicts
         * stacked generics won't be that common in vala */
        | shift_expression OP_SHIFT_RIGHT additive_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_SHIFT_RIGHT, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_SHIFT_RIGHT, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        ;
 
@@ -1053,51 +1163,81 @@ relational_expression
        : shift_expression
        | relational_expression OP_LT shift_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_LESS_THAN, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_LESS_THAN, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        | relational_expression OP_GT shift_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_GREATER_THAN, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_GREATER_THAN, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        | relational_expression OP_LE shift_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_LESS_THAN_OR_EQUAL, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_LESS_THAN_OR_EQUAL, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        | relational_expression OP_GE shift_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_GREATER_THAN_OR_EQUAL, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_GREATER_THAN_OR_EQUAL, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        | relational_expression IS type
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_type_check_new ($1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_type_check_new ($1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        | relational_expression AS type
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_cast_expression_new ($1, $3, src, TRUE));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_cast_expression_new ($1, $3, src, TRUE));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        ;
 
@@ -1105,19 +1245,29 @@ equality_expression
        : relational_expression
        | equality_expression OP_EQ relational_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_EQUALITY, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_EQUALITY, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        | equality_expression OP_NE relational_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_INEQUALITY, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_INEQUALITY, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        ;
 
@@ -1125,11 +1275,16 @@ and_expression
        : equality_expression
        | and_expression BITWISE_AND equality_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_BITWISE_AND, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_BITWISE_AND, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        ;
 
@@ -1137,11 +1292,16 @@ exclusive_or_expression
        : and_expression
        | exclusive_or_expression CARRET and_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_BITWISE_XOR, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_BITWISE_XOR, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        ;
 
@@ -1149,11 +1309,16 @@ inclusive_or_expression
        : exclusive_or_expression
        | inclusive_or_expression BITWISE_OR exclusive_or_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_BITWISE_OR, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_BITWISE_OR, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        ;
 
@@ -1161,11 +1326,16 @@ conditional_and_expression
        : inclusive_or_expression
        | conditional_and_expression OP_AND inclusive_or_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_AND, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_AND, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        ;
 
@@ -1173,11 +1343,16 @@ conditional_or_expression
        : conditional_and_expression
        | conditional_or_expression OP_OR conditional_and_expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_OR, $1, $3, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_binary_expression_new (VALA_BINARY_OPERATOR_OR, $1, $3, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        ;
 
@@ -1185,12 +1360,17 @@ conditional_expression
        : conditional_or_expression
        | conditional_or_expression INTERR expression COLON expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_conditional_expression_new ($1, $3, $5, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
-               g_object_unref ($5);
+               if ($1 == NULL || $3 == NULL || $5 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_conditional_expression_new ($1, $3, $5, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+                       g_object_unref ($5);
+               }
          }
        ;
 
@@ -1268,11 +1448,16 @@ lambda_parameter_list
 assignment
        : unary_expression assignment_operator expression
          {
-               ValaSourceReference *src = src(@2);
-               $$ = VALA_EXPRESSION (vala_assignment_new ($1, $3, $2, src));
-               g_object_unref (src);
-               g_object_unref ($1);
-               g_object_unref ($3);
+               if ($1 == NULL || $3 == NULL) {
+                       // error in subexpression
+                       $$ = NULL;
+               } else {
+                       ValaSourceReference *src = src(@2);
+                       $$ = VALA_EXPRESSION (vala_assignment_new ($1, $3, $2, src));
+                       g_object_unref (src);
+                       g_object_unref ($1);
+                       g_object_unref ($3);
+               }
          }
        ;