eec904f849
Do not spuriously reject constexpr functions that access elements of an array of unknown bound; this may later become valid once the bound is known. Permit array-to-pointer decay on such arrays, but disallow pointer arithmetic (since we do not know whether it will have defined behavior). The standard is not clear on how this should work, but this seems to be a decent answer. Patch by Robert Haberlach! llvm-svn: 301822
26 lines
984 B
C++
26 lines
984 B
C++
// RUN: %clang_cc1 %s -Wno-uninitialized -std=c++1z -fsyntax-only -verify
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const extern int arr[];
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constexpr auto p = arr; // ok
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constexpr int f(int i) {return p[i];} // expected-note {{read of dereferenced one-past-the-end pointer}}
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constexpr int arr[] {1, 2, 3};
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constexpr auto p2 = arr + 2; // ok
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constexpr int x = f(2); // ok
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constexpr int y = f(3); // expected-error {{constant expression}}
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// expected-note-re@-1 {{in call to 'f({{.*}})'}}
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struct A {int m[];} a;
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constexpr auto p3 = a.m; // ok
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constexpr auto p4 = a.m + 1; // expected-error {{constant expression}} expected-note {{constant bound}}
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void g(int i) {
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int arr[i];
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constexpr auto *p = arr + 2; // expected-error {{constant expression}} expected-note {{constant bound}}
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// FIXME: Give a better diagnostic here. The issue is that computing
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// sizeof(*arr2) within the array indexing fails due to the VLA.
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int arr2[2][i];
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constexpr int m = ((void)arr2[2], 0); // expected-error {{constant expression}}
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}
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