llvm-project/clang/test/Sema/compound-literal.c

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A compound literal within a global lambda or block is still within the body of a function for the purposes of computing its storage duration and deciding whether its initializer must be constant. There are a number of problems in our current treatment of compound literals. C specifies that a compound literal yields an l-value referring to an object with either static or automatic storage duration, depending on where it was written; in the latter case, the literal object has a lifetime tied to the enclosing scope (much like an ObjC block), not the enclosing full-expression. To get these semantics fully correct in our current design, we would need to collect compound literals on the ExprWithCleanups, just like we do with ObjC blocks; we would probably also want to identify literals like we do with materialized temporaries. But it gets stranger; GCC adds compound literals to C++ as an extension, but makes them r-values, which are generally assumed to have temporary storage duration. Ignoring destructor ordering, the difference only matters if the object's address escapes the full-expression, which for an r-value can only happen with reference binding (which extends temporaries) or array-to-pointer decay (which does not). GCC then attempts to lock down on array-to-pointer decay in ad hoc ways. Arguably a far superior language solution for C++ (and perhaps even array r-values in C, which can occur in other ways) would be to propagate lifetime extension through array-to-pointer decay, so that initializing a pointer object to a decayed r-value array extends the lifetime of the complete object containing the array. But this would be a major change in semantics which arguably ought to be blessed by the committee(s). Anyway, I'm not fixing any of that in this patch; I did try, but it got out of hand. Fixes rdar://28949016. llvm-svn: 285643
2016-11-01 05:56:26 +08:00
// RUN: %clang_cc1 -fsyntax-only -verify -fblocks -pedantic %s
// REQUIRES: LP64
struct foo { int a, b; };
static struct foo t = (struct foo){0,0};
static struct foo t1 = __builtin_choose_expr(0, (struct foo){0,0}, (struct foo){0,0});
static struct foo t2 = {0,0};
static struct foo t3 = t2; // expected-error {{initializer element is not a compile-time constant}}
static int *p = (int []){2,4};
static int x = (int){1};
static int *p2 = (int []){2,x}; // expected-error {{initializer element is not a compile-time constant}}
static long *p3 = (long []){2,"x"}; // expected-warning {{incompatible pointer to integer conversion initializing 'long' with an expression of type 'char [2]'}}
typedef struct { } cache_t; // expected-warning{{empty struct is a GNU extension}}
static cache_t clo_I1_cache = ((cache_t) { } ); // expected-warning{{use of GNU empty initializer extension}}
typedef struct Test {int a;int b;} Test;
static Test* ll = &(Test) {0,0};
extern void fooFunc(struct foo *pfoo);
int main(int argc, char **argv) {
int *l = (int []){x, *p, *p2};
fooFunc(&(struct foo){ 1, 2 });
}
struct Incomplete; // expected-note{{forward declaration of 'struct Incomplete'}}
struct Incomplete* I1 = &(struct Incomplete){1, 2, 3}; // expected-error {{variable has incomplete type}}
void IncompleteFunc(unsigned x) {
struct Incomplete* I2 = (struct foo[x]){1, 2, 3}; // expected-error {{variable-sized object may not be initialized}}
(void){1,2,3}; // expected-error {{variable has incomplete type}}
(void(void)) { 0 }; // expected-error{{illegal initializer type 'void (void)'}}
}
// PR6080
int array[(sizeof(int[3]) == sizeof( (int[]) {0,1,2} )) ? 1 : -1];
A compound literal within a global lambda or block is still within the body of a function for the purposes of computing its storage duration and deciding whether its initializer must be constant. There are a number of problems in our current treatment of compound literals. C specifies that a compound literal yields an l-value referring to an object with either static or automatic storage duration, depending on where it was written; in the latter case, the literal object has a lifetime tied to the enclosing scope (much like an ObjC block), not the enclosing full-expression. To get these semantics fully correct in our current design, we would need to collect compound literals on the ExprWithCleanups, just like we do with ObjC blocks; we would probably also want to identify literals like we do with materialized temporaries. But it gets stranger; GCC adds compound literals to C++ as an extension, but makes them r-values, which are generally assumed to have temporary storage duration. Ignoring destructor ordering, the difference only matters if the object's address escapes the full-expression, which for an r-value can only happen with reference binding (which extends temporaries) or array-to-pointer decay (which does not). GCC then attempts to lock down on array-to-pointer decay in ad hoc ways. Arguably a far superior language solution for C++ (and perhaps even array r-values in C, which can occur in other ways) would be to propagate lifetime extension through array-to-pointer decay, so that initializing a pointer object to a decayed r-value array extends the lifetime of the complete object containing the array. But this would be a major change in semantics which arguably ought to be blessed by the committee(s). Anyway, I'm not fixing any of that in this patch; I did try, but it got out of hand. Fixes rdar://28949016. llvm-svn: 285643
2016-11-01 05:56:26 +08:00
// rdar://28949016 - Constant restriction should not apply to compound literals in blocks
int (^block)(int) = ^(int i) {
int *array = (int[]) {i, i + 2, i + 4};
return array[i];
};