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This builtin is supported by GCC and is a way to improve diagnostic behavior for va_start in C23 mode. C23 no longer requires a second argument to the va_start macro in support of variadic functions with no leading parameters. However, we still want to diagnose passing more than two arguments, or diagnose when passing something other than the last parameter in the variadic function. This also updates the freestanding <stdarg.h> header to use the new builtin, same as how GCC works. Fixes #124031
44 lines
3.2 KiB
C
44 lines
3.2 KiB
C
// RUN: %clang_cc1 -std=c23 -fsyntax-only -ffreestanding -verify=expected,both %s -triple i386-pc-unknown
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// RUN: %clang_cc1 -std=c23 -fsyntax-only -ffreestanding -verify=expected,both %s -triple x86_64-apple-darwin9
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// RUN: %clang_cc1 -std=c23 -fsyntax-only -ffreestanding -fms-compatibility -verify=expected,both %s -triple x86_64-pc-win32
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// RUN: %clang_cc1 -std=c17 -fsyntax-only -ffreestanding -verify=both,pre-c23 %s
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void foo(int x, int y, ...) {
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__builtin_va_list list;
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__builtin_c23_va_start(); // pre-c23-error {{use of unknown builtin '__builtin_c23_va_start'}} \
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expected-error{{too few arguments to function call, expected 1, have 0}}
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// Note, the unknown builtin diagnostic is only issued once per function,
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// which is why the rest of the lines do not get the same diagonstic.
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__builtin_c23_va_start(list); // ok
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__builtin_c23_va_start(list, 0); // expected-warning {{second argument to 'va_start' is not the last non-variadic parameter}}
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__builtin_c23_va_start(list, x); // expected-warning {{second argument to 'va_start' is not the last non-variadic parameter}}
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__builtin_c23_va_start(list, y); // ok
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__builtin_c23_va_start(list, 0, 1); // expected-error {{too many arguments to function call, expected at most 2, have 3}}
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__builtin_c23_va_start(list, y, y); // expected-error {{too many arguments to function call, expected at most 2, have 3}}
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}
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// Test the same thing as above, only with the macro from stdarg.h. This will
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// not have the unknown builtin diagnostics, but will have different
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// diagnostics between C23 and earlier modes.
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#include <stdarg.h>
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void bar(int x, int y, ...) {
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// FIXME: the "use of undeclared identifier 'va_start'" diagnostics is an odd
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// follow-on diagnostic that should be silenced.
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va_list list;
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va_start(); // pre-c23-error {{too few arguments provided to function-like macro invocation}} \
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pre-c23-error {{use of undeclared identifier 'va_start'}} \
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expected-error{{too few arguments to function call, expected 1, have 0}}
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va_start(list); // pre-c23-error {{too few arguments provided to function-like macro invocation}} \
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pre-c23-error {{use of undeclared identifier 'va_start'}}
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va_start(list, 0); // both-warning {{second argument to 'va_start' is not the last non-variadic parameter}}
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va_start(list, x); // both-warning {{second argument to 'va_start' is not the last non-variadic parameter}}
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va_start(list, y); // ok
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va_start(list, 0, 1); // pre-c23-error {{too many arguments provided to function-like macro invocation}} \
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pre-c23-error {{use of undeclared identifier 'va_start'}} \
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expected-error {{too many arguments to function call, expected at most 2, have 3}}
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va_start(list, y, y); // pre-c23-error {{too many arguments provided to function-like macro invocation}} \
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pre-c23-error {{use of undeclared identifier 'va_start'}} \
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expected-error {{too many arguments to function call, expected at most 2, have 3}}
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// pre-c23-note@__stdarg_va_arg.h:* 4 {{macro 'va_start' defined here}}
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}
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