================
@@ -1472,3 +1472,25 @@ template<typename T> struct Outer {
};
};
Outer<int>::Inner outerinner;
+
+void aggregate() {
+ struct B {
+ [[clang::explicit_init]] int f1;
+ };
+
+ struct S : B { // expected-warning {{uninitialized}}
+ int f2;
+ int f3 [[clang::explicit_init]];
+ };
+
+#if __cplusplus >= 202002L
+ S a({}, 0); // expected-warning {{'f1' is left uninitialized}}
expected-warning {{'f3' is left uninitialized}}
+#endif
+ S b{.f3 = 1}; // expected-warning {{'f1' is left uninitialized}}
+ S c{.f2 = 5}; // expected-warning {{'f1' is left uninitialized}}
expected-warning {{'f3' is left uninitialized}} expected-warning {{'f3' is left
uninitialized}}
+ c = {{}, 0}; // expected-warning {{'f1' is left uninitialized}}
expected-warning {{'f3' is left uninitialized}}
+ S d; // expected-warning {{uninitialized}} expected-note {{constructor}}
----------------
higher-performance wrote:
I don't think we should leave this out. Allowing this big of a loophole would
defeat the purpose of the attribute, which is to ensure that callers don't
forget to initialize a field that has been added to the struct.
The best analogy I would think of here is function parameters. If a parameter
is added, an argument must be passed for it -- we don't attempt to provide
callers a way to work around that; that's a hard requirement, and by design.
Note that if the diagnostic caused retroactive errors in _existing_ code, I
would agree. But all it does is to merely trigger a warning for the applicable
fields moving forward. It's up to the author of the field to determine if this
is what they want -- if it isn't, then they can just avoid applying it.
I _could_ see a future where Clang slightly relaxes the requirement to allow
that coding style, iff it can prove that the fields are all trivial & then
assigned to prior the usage of the object. That seems perfectly fine to me,
because at no point it opens such a loophole. (Also note that closing a
loophole we left open will be much more painful than relaxing the syntactic
requirement.)
https://github.com/llvm/llvm-project/pull/102040
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