llvm-project/clang/test/Parser/declarators.c
Aaron Ballman 11da1b53d8 [C89/C2x] Improve diagnostics around strict prototypes in C
Functions without prototypes in C (also known as K&R C functions) were
introduced into C89 as a deprecated feature and C2x is now reclaiming
that syntax space with different semantics. However, Clang's
-Wstrict-prototypes diagnostic is off-by-default (even in pedantic
mode) and does not suffice to warn users about issues in their code.

This patch changes the behavior of -Wstrict-prototypes to only diagnose
declarations and definitions which are not going to change behavior in
C2x mode, and enables the diagnostic in -pedantic mode. The diagnostic
is now specifically about the fact that the feature is deprecated.

It also adds -Wdeprecated-non-prototype, which is grouped under
-Wstrict-prototypes and diagnoses declarations or definitions which
will change behavior in C2x mode. This diagnostic is enabled by default
because the risk is higher for the user to continue to use the
deprecated feature.

Differential Revision: https://reviews.llvm.org/D122895
2022-04-08 16:19:58 -04:00

160 lines
5.2 KiB
C

// RUN: %clang_cc1 %s -fsyntax-only -verify -pedantic -std=c99
extern int a1[];
void f0(); /* expected-warning {{a function declaration without a prototype is deprecated in all versions of C}} */
void f1(int [*]);
void f2(int [const *]);
void f3(int [volatile const*]);
int f4(*XX)(void); /* expected-error {{cannot return}} expected-warning {{type specifier missing, defaults to 'int'}} */
int f5(int [static]); /* expected-error {{'static' may not be used without an array size}} */
char ((((*X))));
void (*signal(int, void (*)(int)))(int);
int aaaa, ***C, * const D, B(int);
int *A;
struct str;
void test2(int *P, int A) {
struct str;
// Hard case for array decl, not Array[*].
int Array[*(int*)P+A];
}
typedef int atype;
void test3(x, /* expected-warning {{a function declaration without a prototype is deprecated in all versions of C and is not supported in C2x}} */
atype /* expected-error {{unexpected type name 'atype': expected identifier}} */
) int x, atype; {}
void test4(x, x) int x; {} // expected-error {{redefinition of parameter 'x'}} \
// expected-warning {{a function declaration without a prototype is deprecated in all versions of C and is not supported in C2x}}
// PR3031
int (test5), ; // expected-error {{expected identifier or '('}}
// PR3963 & rdar://6759604 - test error recovery for mistyped "typenames".
foo_t *d; // expected-error {{unknown type name 'foo_t'}}
foo_t a; // expected-error {{unknown type name 'foo_t'}}
int test6() { /* expected-warning {{a function declaration without a prototype is deprecated in all versions of C}} */
return a; // a should be declared.
}
// Use of tagged type without tag. rdar://6783347
struct xyz { int y; };
enum myenum { ASDFAS };
xyz b; // expected-error {{must use 'struct' tag to refer to type 'xyz'}}
myenum c; // expected-error {{must use 'enum' tag to refer to type 'myenum'}}
float *test7(void) {
// We should recover 'b' by parsing it with a valid type of "struct xyz", which
// allows us to diagnose other bad things done with y, such as this.
return &b.y; // expected-warning {{incompatible pointer types returning 'int *' from a function with result type 'float *'}}
}
struct xyz test8(void) { return a; } // a should be be marked invalid, no diag.
// Verify that implicit int still works.
static f; // expected-warning {{type specifier missing, defaults to 'int'}}
static g = 4; // expected-warning {{type specifier missing, defaults to 'int'}}
static h // expected-warning {{type specifier missing, defaults to 'int'}}
__asm__("foo");
struct test9 {
int x // expected-error {{expected ';' at end of declaration list}}
int y;
int z // expected-warning {{expected ';' at end of declaration list}}
};
// PR6208
struct test10 { int a; } static test10x;
struct test11 { int a; } const test11x;
// PR6216
void test12(void) {
(void)__builtin_offsetof(struct { char c; int i; }, i);
}
// rdar://7608537
struct test13 { int a; } (test13x);
// <rdar://problem/8044088>
struct X<foo::int> { }; // expected-error{{expected identifier or '('}}
// PR7617 - error recovery on missing ;.
void test14(void) // expected-error {{expected ';' after top level declarator}}
void test14a(void);
void *test14b = (void*)test14a; // Make sure test14a didn't get skipped.
// rdar://problem/8358508
long struct X { int x; } test15(void); // expected-error {{'long struct' is invalid}}
void test16(i) int i j; { } // expected-error {{expected ';' at end of declaration}} \
// expected-warning {{a function declaration without a prototype is deprecated in all versions of C and is not supported in C2x}}
void test17(i, j) int i, j k; { } // expected-error {{expected ';' at end of declaration}} \
// expected-warning {{a function declaration without a prototype is deprecated in all versions of C and is not supported in C2x}}
void knrNoSemi(i) int i { } // expected-error {{expected ';' at end of declaration}} \
// expected-warning {{a function declaration without a prototype is deprecated in all versions of C and is not supported in C2x}}
// PR12595
void test18(void) {
int x = 4+(5-12)); // expected-error {{extraneous ')' before ';'}}
}
enum E1 { e1 }: // expected-error {{expected ';'}}
struct EnumBitfield { // expected-warning {{struct without named members is a GNU extension}}
enum E2 { e2 } : 4; // ok
struct S { int n; }: // expected-error {{expected ';'}}
// expected-warning@-1 {{declaration does not declare anything}}
};
// PR10982
enum E11 {
A1 = 1,
};
enum E12 {
, // expected-error{{expected identifier}}
A2
};
void func_E12(enum E12 *p) { *p = A2; }
enum E13 {
1D, // expected-error{{expected identifier}}
A3
};
void func_E13(enum E13 *p) { *p = A3; }
enum E14 {
A4 12, // expected-error{{expected '= constant-expression' or end of enumerator definition}}
A4a
};
void func_E14(enum E14 *p) { *p = A4a; }
enum E15 {
A5=12 4, // expected-error{{expected '}' or ','}}
A5a
};
void func_E15(enum E15 *p) { *p = A5a; }
enum E16 {
A6; // expected-error{{expected '= constant-expression' or end of enumerator definition}}
A6a
};
int PR20634 = sizeof(struct { int n; } [5]);