gcc-10 compilation failure in c_expr_sizeof_expr

[Colin Ian King]

gcc version 10.2.0 (Ubuntu 10.2.0-17ubuntu1)

$ cat qq.c

int m(int a, int b) { return sizeof((char[a][b])); }

gcc qq.c
qq.c: In function ‘m’:
qq.c:1:49: error: expected expression before ‘)’ token
    1 | int m(int a, int b) { return sizeof((char[a][b])); }
      | ^
qq.c:1:49: internal compiler error: tree check: expected class ‘type’, have ‘exceptional’ (error_mark) in c_expr_sizeof_expr, at c/c-typeck.c:2946
0x764982 tree_class_check_failed(tree_node const*, tree_code_class, char const*, int, char const*)
 ../../src/gcc/tree.c:9780
0x5c561d tree_class_check(tree_node*, tree_code_class, char const*, int, char const*)
 ../../src/gcc/tree.h:3417
0x5c561d c_expr_sizeof_expr(unsigned int, c_expr)
 ../../src/gcc/c/c-typeck.c:2946
0xa2c748 c_parser_sizeof_expression
 ../../src/gcc/c/c-parser.c:8348
0xa2c748 c_parser_unary_expression
 ../../src/gcc/c/c-parser.c:8245
0xa2d38d c_parser_cast_expression
 ../../src/gcc/c/c-parser.c:8115
0xa2d619 c_parser_binary_expression
 ../../src/gcc/c/c-parser.c:7918
0xa2e5f5 c_parser_conditional_expression
 ../../src/gcc/c/c-parser.c:7652
0xa2ec10 c_parser_expr_no_commas
 ../../src/gcc/c/c-parser.c:7569
0xa2ee71 c_parser_expression
 ../../src/gcc/c/c-parser.c:10644
0xa2f617 c_parser_expression_conv
 ../../src/gcc/c/c-parser.c:10677
0xa25af1 c_parser_statement_after_labels
 ../../src/gcc/c/c-parser.c:6212
0xa26fa1 c_parser_compound_statement_nostart
 ../../src/gcc/c/c-parser.c:5805
0xa45a74 c_parser_compound_statement
 ../../src/gcc/c/c-parser.c:5617
0xa47531 c_parser_declaration_or_fndef
 ../../src/gcc/c/c-parser.c:2505
0xa4f6a3 c_parser_external_declaration
 ../../src/gcc/c/c-parser.c:1745
0xa501a9 c_parser_translation_unit
 ../../src/gcc/c/c-parser.c:1618
0xa501a9 c_parse_file()
 ../../src/gcc/c/c-parser.c:21752
0xaa81d3 c_common_parse_file()
 ../../src/gcc/c-family/c-opts.c:1190
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <file:///usr/share/doc/gcc-10/README.Bugs> for instructions.

[Colin Ian King (colin-king)]

Note that the workaround is just to remove the extra ( ), e.g. int m(int a, int b) { return sizeof(char[a][b]); }

[Colin Ian King (colin-king)]

Fails in the same way with just: int m(int a) { return sizeof((char[a])); };

[Colin Ian King (colin-king)]

Regression; this does not crash the compiler with gcc-9.3.0

[Matthias Klose (doko)]

confirmed, but that's invalid code:

$ gcc-9 -c qq.i
qq.i: In function ‘m’:
qq.i:1:49: error: expected expression before ‘)’ token
    1 | int m(int a, int b) { return sizeof((char[a][b])); }
      | ^

[Matthias Klose (doko)]

seen with the gcc-10 branch and the trunk, gcc configured with
--enable-checking=yes,extra,rtl

gcc-9 configured here with --enable-checking=release, so I don't know if that's a regression.

$ cat qq.i
int m(int a) { return sizeof((char[a])); };

$ gcc-9 -c qq.i
qq.i: In function ‘m’:
qq.i:1:39: error: expected expression before ‘)’ token
    1 | int m(int a) { return sizeof((char[a])); };
      | ^

$ gcc-10 -c qq.i
qq.i: In function ‘m’:
qq.i:1:39: error: expected expression before ‘)’ token
    1 | int m(int a) { return sizeof((char[a])); };
      | ^
qq.i:1:39: internal compiler error: tree check: expected class ‘type’, have ‘exceptional’ (error_mark) in c_expr_sizeof_expr, at c/c-typeck.c:2946
0x7602ef tree_class_check_failed(tree_node const*, tree_code_class, char const*, int, char const*)
        ../../src/gcc/tree.c:9780
0x5c2697 tree_class_check(tree_node*, tree_code_class, char const*, int, char const*)
        ../../src/gcc/tree.h:3417
0x5c2697 c_expr_sizeof_expr(unsigned int, c_expr)
        ../../src/gcc/c/c-typeck.c:2946
0xa274b7 c_parser_sizeof_expression
        ../../src/gcc/c/c-parser.c:8348
0xa274b7 c_parser_unary_expression
        ../../src/gcc/c/c-parser.c:8245
0xa280fd c_parser_cast_expression
        ../../src/gcc/c/c-parser.c:8115
0xa28389 c_parser_binary_expression
        ../../src/gcc/c/c-parser.c:7918
0xa29365 c_parser_conditional_expression
        ../../src/gcc/c/c-parser.c:7652
0xa29980 c_parser_expr_no_commas
        ../../src/gcc/c/c-parser.c:7569
0xa29be1 c_parser_expression
        ../../src/gcc/c/c-parser.c:10644
0xa2a387 c_parser_expression_conv
        ../../src/gcc/c/c-parser.c:10677
0xa20861 c_parser_statement_after_labels
        ../../src/gcc/c/c-parser.c:6212
0xa21d11 c_parser_compound_statement_nostart
        ../../src/gcc/c/c-parser.c:5805
0xa407c4 c_parser_compound_statement
        ../../src/gcc/c/c-parser.c:5617
0xa42281 c_parser_declaration_or_fndef
        ../../src/gcc/c/c-parser.c:2505
0xa4a3f3 c_parser_external_declaration
        ../../src/gcc/c/c-parser.c:1745
0xa4aef1 c_parser_translation_unit
        ../../src/gcc/c/c-parser.c:1618
0xa4aef1 c_parse_file()
        ../../src/gcc/c/c-parser.c:21752
0xaa21fb c_common_parse_file()
        ../../src/gcc/c-family/c-opts.c:1190
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.

[Marxin-m (marxin-m)]

It's at least as old as GCC 4.8.0.

[Rguenth (rguenth)]

GCC 10.3 is being released, retargeting bugs to GCC 10.4.

[Pinskia (pinskia)]

Dup of bug 101171.

*** This bug has been marked as a duplicate of bug 101171 ***

[Matthias Klose (doko)]

fixed in 10.5.0

[Colin Ian King (colin-king)]

Thanks doko!