[patch, fortan] PR87103 - [OOP] ICE in gfc_new_symbol() due to overlong symbol name

[Andrew Benson <abenson at carnegiescience dot edu>]

As suggested by Janus, PR87103 is easily fixed by the attached patch which 
increases GFC_MAX_SYMBOL_LEN to 76 (sufficient to hold the maximum allowed F08 
symbol length of 63, plus a null terminator, plus the "__tmp_class_" prefix).

Bootstraps and regtests successfully.

OK for trunk?

-Andrew

On Saturday, August 25, 2018 1:50:57 PM PDT Andrew Benson wrote:
> I just opened PR for this: 87103
> 
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87103
> 
> The following code causes an ICE with gfortan 9.0.0 (r263855):
> 
> module a
>   type :: nameThatIsVeryLongButNotTooLongThatItShouldBeInvalid
>   end type nameThatIsVeryLongButNotTooLongThatItShouldBeInvalid
> contains
>   subroutine b(self)
>     class(nameThatIsVeryLongButNotTooLongThatItShouldBeInvalid), intent(in)
> :: self
>     select type (self)
>     class is (nameThatIsVeryLongButNotTooLongThatItShouldBeInvalid)
>     end select
>   end subroutine b
> end module a
> 
> $ gfortran -v
> Using built-in specs.
> COLLECT_GCC=gfortran
> COLLECT_LTO_WRAPPER=/home/abenson/Galacticus/Tools/libexec/gcc/x86_64-pc-
> linux-gnu/9.0.0/lto-wrapper
> Target: x86_64-pc-linux-gnu
> Configured with: ../gcc-trunk/configure
> --prefix=/home/abenson/Galacticus/Tools --enable-languages=c,c++,fortran
> --disable-multilib : (reconfigured) ../gcc- trunk/configure
> --prefix=/home/abenson/Galacticus/Tools --enable-languages=c,c+ +,fortran
> --disable-multilib : (reconfigured) ../gcc-trunk/configure --prefix=/
> home/abenson/Galacticus/Tools --disable-multilib --enable-languages=c,c+
> +,fortran,lto --no-create --no-recursion : (reconfigured)
> ../gcc-trunk/configure --prefix=/home/abenson/Galacticus/Tools
> --disable-multilib --enable- languages=c,c++,fortran,lto --no-create
> --no-recursion : (reconfigured) ../gcc- trunk/configure
> --prefix=/home/abenson/Galacticus/Tools --disable-multilib --
> enable-languages=c,c++,fortran,lto --no-create --no-recursion
> Thread model: posix
> gcc version 9.0.0 20180825 (experimental) (GCC)
> 
> 
> $ gfortran -c tmp1.F90 -o tmp1.o
> f951: internal compiler error: new_symbol(): Symbol name too long
> 0x7b9711 gfc_internal_error(char const*, ...)
>         ../../gcc-trunk/gcc/fortran/error.c:1362
> 0x84a838 gfc_new_symbol(char const*, gfc_namespace*)
>         ../../gcc-trunk/gcc/fortran/symbol.c:3132
> 0x84ab97 gfc_get_sym_tree(char const*, gfc_namespace*, gfc_symtree**, bool)
>         ../../gcc-trunk/gcc/fortran/symbol.c:3373
> 0x7e565d select_type_set_tmp
>         ../../gcc-trunk/gcc/fortran/match.c:6114
> 0x7ee260 gfc_match_class_is()
>         ../../gcc-trunk/gcc/fortran/match.c:6470
> 0x808c79 match_word
>         ../../gcc-trunk/gcc/fortran/parse.c:65
> 0x80a4f1 decode_statement
>         ../../gcc-trunk/gcc/fortran/parse.c:462
> 0x80d04c next_free
>         ../../gcc-trunk/gcc/fortran/parse.c:1234
> 0x80d04c next_statement
>         ../../gcc-trunk/gcc/fortran/parse.c:1466
> 0x810861 parse_select_type_block
>         ../../gcc-trunk/gcc/fortran/parse.c:4236
> 0x810861 parse_executable
>         ../../gcc-trunk/gcc/fortran/parse.c:5330
> 0x8118e6 parse_progunit
>         ../../gcc-trunk/gcc/fortran/parse.c:5697
> 0x811bfc parse_contained
>         ../../gcc-trunk/gcc/fortran/parse.c:5574
> 0x812a4c parse_module
>         ../../gcc-trunk/gcc/fortran/parse.c:5944
> 0x812f75 gfc_parse_file()
>         ../../gcc-trunk/gcc/fortran/parse.c:6247
> 0x859d3f gfc_be_parse_file
>         ../../gcc-trunk/gcc/fortran/f95-lang.c:204
> Please submit a full bug report,
> with preprocessed source if appropriate.
> Please include the complete backtrace with any bug report.
> See <https://gcc.gnu.org/bugs/> for instructions.
> 
> 
> The problem seems to be that gfc_new_symbol() is passed a name
> '__tmp_class_namethatisverylongbutnottoolongthatitshouldbeinvalid' in this
> case which exceeds GFC_MAX_SYMBOL_LEN=64. My understanding is that the code
> is valid since the symbol name itself,
> 'namethatisverylongbutnottoolongthatitshouldbeinvalid', is less than 64
> characters.
> 
> I'm not sure what the correct fix for this is - should the name length limit
> in gfc_new_symbol() just be increased by enough to allow the '__tmp_class_'
> prefix?
> 
> This appears to be a regression as the same code (with the same long-but-
> legal) symbol names compiled under earlier versions of gfortran. I'll
> attempt to rollback to previous versions and see if I can identify where
> the change occurred.
> 
> -Andrew

2018-09-04  Andrew Benson  <abensonca@gmail.com>

	* gfortan.h: Increase GFC_MAX_SYMBOL_LEN to 76, sufficient to hold
	the maximum allowed F08 symbol length of 63, plus a null
	terminator, plus the "__tmp_class_" prefix.

Index: gcc/fortran/gfortran.h
===================================================================
--- gcc/fortran/gfortran.h	(revision 264085)
+++ gcc/fortran/gfortran.h	(working copy)
@@ -54,7 +54,9 @@ not after.
 
 /* Major control parameters.  */
 
-#define GFC_MAX_SYMBOL_LEN 63   /* Must be at least 63 for F2003.  */
+/* Must be at least 63 for F2003, +1 for null terminator,
+ +12 for prefix "__tmp_class_".  */
+#define GFC_MAX_SYMBOL_LEN 76
 #define GFC_LETTERS 26		/* Number of letters in the alphabet.  */
 
 #define MAX_SUBRECORD_LENGTH 2147483639   /* 2**31-9 */