Crash when extern function item has no return type

[philberty]

extern "C" {
    fn puts(s: *const i8);
}

fn main() {
    unsafe {
        let a = "foo\0";
        let b = a as *const str;
        let c = b as *const i8;
        puts(c);
    }
}

Program received signal SIGSEGV, Segmentation fault.                                                                                                                                                                                                   
Rust::AST::ExternalFunctionItem::as_string[abi:cxx11]() const (this=0x3d35f50) at ../../gccrs/gcc/rust/ast/rust-ast-full-test.cc:3598                                                                                                                  
3598      str += "\n (return) Type: " + return_type->as_string ();                                                                                                                                                                                     
(gdb) bt                                                                                                                   
#0  Rust::AST::ExternalFunctionItem::as_string[abi:cxx11]() const (this=0x3d35f50) at ../../gccrs/gcc/rust/ast/rust-ast-full-test.cc:3598
#1  0x0000000000e9e12a in Rust::AST::ExternBlock::as_string[abi:cxx11]() const (this=0x3cfc820) at ../../gccrs/gcc/rust/ast/rust-ast-full-test.cc:1316                                                                                                 
#2  0x0000000000e9875e in Rust::AST::Crate::as_string[abi:cxx11]() const (this=0x7fffffffd4e0) at ../../gccrs/gcc/rust/ast/rust-ast-full-test.cc:197                                                                                                   
#3  0x0000000000f2940e in Rust::Parser<Rust::Lexer>::debug_dump_ast_output (this=0x7fffffffd5d0, crate=..., out=...) at ../../gccrs/gcc/rust/parse/rust-parse-impl.h:14890                                                                             
#4  0x0000000000f0ea55 in Rust::Session::dump_ast (this=0x3b87820 <session>, parser=..., crate=...) at ../../gccrs/gcc/rust/rust-session-manager.cc:852                                                                                                
#5  0x0000000000f0d3fe in Rust::Session::parse_file (this=0x3b87820 <session>, filename=0x7fffffffe029 "test.rs") at ../../gccrs/gcc/rust/rust-session-manager.cc:494                                                                                  
#6  0x0000000000f0d1fb in Rust::Session::parse_files (this=0x3b87820 <session>, num_files=1, files=0x3d47a20) at ../../gccrs/gcc/rust/rust-session-manager.cc:458
#7  0x0000000000e68265 in grs_langhook_parse_file () at ../../gccrs/gcc/rust/rust-lang.cc:171
#8  0x00000000018bb23b in compile_file () at ../../gccrs/gcc/toplev.c:457
#9  0x00000000018be509 in do_compile () at ../../gccrs/gcc/toplev.c:2201
#10 0x00000000018be838 in toplev::main (this=0x7fffffffdad6, argc=18, argv=0x7fffffffdbe8) at ../../gccrs/gcc/toplev.c:2340
#11 0x0000000002ac7c7d in main (argc=18, argv=0x7fffffffdbe8) at ../../gccrs/gcc/main.c:39

Originally posted by @philberty in #421 (comment)

[bugaevc]

I'm still getting an error with 5b3909d when trying to compile this example:

$ bin/gccrs test.rs 
Preparing to parse files. 
Attempting to parse file: test.rs
beginning null denotation identifier handling
current peek token when starting path pratt parse: 'as'
current token (just about to return path to null denotation): 'as'
finished null denotation identifier path parsing - next is branching 
beginning null denotation identifier handling
current peek token when starting path pratt parse: 'as'
current token (just about to return path to null denotation): 'as'
finished null denotation identifier path parsing - next is branching 
beginning null denotation identifier handling
current peek token when starting path pratt parse: '('
current token (just about to return path to null denotation): '('
finished null denotation identifier path parsing - next is branching 
beginning null denotation identifier handling
current peek token when starting path pratt parse: ')'
current token (just about to return path to null denotation): ')'
finished null denotation identifier path parsing - next is branching 
SUCCESSFULLY PARSED CRATE 
ran register_plugins (with no body)
SUCCESSFULLY REGISTERED PLUGINS 
started injection
finished injection
SUCCESSFULLY FINISHED INJECTION 
started expansion
finished expansion
SUCCESSFULLY FINISHED EXPANSION 
test.rs:6:5: fatal error: Failed to lower expr: [UnsafeBlockExpr:
  outer attributes: noneBlockExpr:

  outer attributes: none
  inner attributes: none
 statements: 
 
  outer attributes: none
 let a = foo
 
  outer attributes: none
 let b = a as *const str
 
  outer attributes: none
 let c = b as *const i8
 ExprStmtWithoutBlock:
  CallExpr: 
   outer attributes: none
 Function expr: puts
 Call params:
  c
 final expression: none

]
    6 |     unsafe {
      |     ^
compilation terminated

[philberty]

I'm still getting an error with 5b3909d when trying to compile this example:

$ bin/gccrs test.rs 
Preparing to parse files. 
Attempting to parse file: test.rs
beginning null denotation identifier handling
current peek token when starting path pratt parse: 'as'
current token (just about to return path to null denotation): 'as'
finished null denotation identifier path parsing - next is branching 
beginning null denotation identifier handling
current peek token when starting path pratt parse: 'as'
current token (just about to return path to null denotation): 'as'
finished null denotation identifier path parsing - next is branching 
beginning null denotation identifier handling
current peek token when starting path pratt parse: '('
current token (just about to return path to null denotation): '('
finished null denotation identifier path parsing - next is branching 
beginning null denotation identifier handling
current peek token when starting path pratt parse: ')'
current token (just about to return path to null denotation): ')'
finished null denotation identifier path parsing - next is branching 
SUCCESSFULLY PARSED CRATE 
ran register_plugins (with no body)
SUCCESSFULLY REGISTERED PLUGINS 
started injection
finished injection
SUCCESSFULLY FINISHED INJECTION 
started expansion
finished expansion
SUCCESSFULLY FINISHED EXPANSION 
test.rs:6:5: fatal error: Failed to lower expr: [UnsafeBlockExpr:
  outer attributes: noneBlockExpr:

  outer attributes: none
  inner attributes: none
 statements: 
 
  outer attributes: none
 let a = foo
 
  outer attributes: none
 let b = a as *const str
 
  outer attributes: none
 let c = b as *const i8
 ExprStmtWithoutBlock:
  CallExpr: 
   outer attributes: none
 Function expr: puts
 Call params:
  c
 final expression: none

]
    6 |     unsafe {
      |     ^
compilation terminated

Is this with the testcase from the issue above?

[bugaevc]

Yes.

But this might be the same issue as #421, so perhaps I just spoke too soon 🙂

[philberty]

I wonder are you able to run any of the expected pass testcases for unsafe over in:

https://github.com/Rust-GCC/gccrs/blob/master/gcc/testsuite/rust/compile/torture/unsafe1.rs

Maybe something else is going on if you have the latest code it should be lowering the unsafe to HIR at the moment.

[bugaevc]

With 5b3909d, no, it gives a similar error:

$ bin/gccrs ../src/gcc/testsuite/rust/compile/torture/unsafe1.rs 
Preparing to parse files. 
Attempting to parse file: ../src/gcc/testsuite/rust/compile/torture/unsafe1.rs
beginning null denotation identifier handling
current peek token when starting path pratt parse: '='
current token (just about to return path to null denotation): '='
finished null denotation identifier path parsing - next is branching 
beginning null denotation identifier handling
current peek token when starting path pratt parse: '}'
current token (just about to return path to null denotation): '}'
finished null denotation identifier path parsing - next is branching 
beginning null denotation identifier handling
current peek token when starting path pratt parse: '='
current token (just about to return path to null denotation): '='
finished null denotation identifier path parsing - next is branching 
beginning null denotation identifier handling
current peek token when starting path pratt parse: '('
current token (just about to return path to null denotation): '('
finished null denotation identifier path parsing - next is branching 
SUCCESSFULLY PARSED CRATE 
ran register_plugins (with no body)
SUCCESSFULLY REGISTERED PLUGINS 
started injection
finished injection
SUCCESSFULLY FINISHED INJECTION 
started expansion
finished expansion
SUCCESSFULLY FINISHED EXPANSION 
../src/gcc/testsuite/rust/compile/torture/unsafe1.rs:2:5: fatal error: Failed to lower expr: [UnsafeBlockExpr:
  outer attributes: noneBlockExpr:

  outer attributes: none
  inner attributes: none
 statements: 
 
  outer attributes: none
 let a
 ExprStmtWithoutBlock:
  AssignmentExpr: 
 left: a
 right: 123
 final expression: 
a

]
    2 |     unsafe {
      |     ^
compilation terminated.

But with b992c80 the testcase now builds! 🎉

The puts example still runs into an error:

$ bin/gccrs test.rs 
test.rs:10:9: error: reverse lookup failure
   10 |         puts(c);
      |         ^
test.rs:10:9: error: failed to type resolve expression
test.rs:10:9: error: Failed to resolve expression of function call
test.rs:10:9: error: failed to type resolve expression

[philberty]

Ah yes, this PR #598 fixes that. I am just having some trouble with dejagnu for this test which I am working through before I merge it.