Fix endless recursion due to type scoping

this change fixes building of invalid types. The inner scope struct P is return type of the forward decl foobar. The outer scope foobar() call implicitely declares that function again, with int return type; overall this leads to access within the sym free list, effectively building up a type directly referring to itself, leading to endless recursion later. The testcase is: void n(void) { { struct P { int __val; }; struct P foobar(); // 1 } foobar(); // 2 } I've not included it in tests2 for now, because tcc accepts this. Ideally we would like to reject it (as 'int foobar();' is incompatible with the earlier decl). clang also accepts it, but only because it's not handling (1) above as an implicit decl of foobar (it warns, and with -pedantic also warns about the type incompatiblity). GCC rejects this. Implementing that in tcc requires some surgery, as we need to differ between these cases: { struct P foo(int); // 1 foo(); // no implicit decl, call to foo from 1 } and { { struct P foo(int); // 2 } foo(); // implicit decl, _incompatible_ with 2 }

MMMichael Matz committed 5 years ago