7d644e1215
C89 had a questionable feature where the compiler would implicitly declare a function that the user called but was never previously declared. The resulting function would be globally declared as extern int func(); -- a function without a prototype which accepts zero or more arguments. C99 removed support for this questionable feature due to severe security concerns. However, there was no deprecation period; C89 had the feature, C99 didn't. So Clang (and GCC) both supported the functionality as an extension in C99 and later modes. C2x no longer supports that function signature as it now requires all functions to have a prototype, and given the known security issues with the feature, continuing to support it as an extension is not tenable. This patch changes the diagnostic behavior for the -Wimplicit-function-declaration warning group depending on the language mode in effect. We continue to warn by default in C89 mode (due to the feature being dangerous to use). However, because this feature will not be supported in C2x mode, we've diagnosed it as being invalid for so long, the security concerns with the feature, and the trivial workaround for users (declare the function), we now default the extension warning to an error in C99-C17 mode. This still gives users an easy workaround if they are extensively using the extension in those modes (they can disable the warning or use -Wno-error to downgrade the error), but the new diagnostic makes it more clear that this feature is not supported and should be avoided. In C2x mode, we no longer allow an implicit function to be defined and treat the situation the same as any other lookup failure. Differential Revision: https://reviews.llvm.org/D122983
120 lines
2.6 KiB
C
120 lines
2.6 KiB
C
// RUN: %clang_cc1 -no-opaque-pointers -std=c89 -w -fmerge-all-constants -emit-llvm < %s | FileCheck %s
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// CHECK: @test1.x = internal constant [12 x i32] [i32 1
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// CHECK: @__const.test2.x = private unnamed_addr constant [13 x i32] [i32 1,
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// CHECK: @test5w = {{(dso_local )?}}global { i32, [4 x i8] } { i32 2, [4 x i8] undef }
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// CHECK: @test5y = {{(dso_local )?}}global { double } { double 7.300000e+0{{[0]*}}1 }
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// CHECK: @__const.test6.x = private unnamed_addr constant %struct.SelectDest { i8 1, i8 2, i32 3, i32 0 }
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// CHECK: @test7 = {{(dso_local )?}}global [2 x %struct.test7s] [%struct.test7s { i32 1, i32 2 }, %struct.test7s { i32 4, i32 0 }]
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void test1(void) {
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// This should codegen as a "@test1.x" global.
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const int x[] = { 1, 2, 3, 4, 6, 8, 9, 10, 123, 231, 123,23 };
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foo(x);
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// CHECK: @test1()
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// CHECK: {{call.*@foo.*@test1.x}}
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}
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// rdar://7346691
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void test2(void) {
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// This should codegen as a "@test2.x" global + memcpy.
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int x[] = { 1, 2, 3, 4, 6, 8, 9, 10, 123, 231, 123,23, 24 };
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foo(x);
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// CHECK: @test2()
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// CHECK: %x = alloca [13 x i32]
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// CHECK: call void @llvm.memcpy
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// CHECK: call{{.*}}@foo{{.*}}i32* noundef %
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}
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void test3(void) {
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// This should codegen as a memset.
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int x[100] = { 0 };
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foo(x);
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// CHECK: @test3()
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// CHECK: %x = alloca [100 x i32]
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// CHECK: call void @llvm.memset
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}
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void test4(void) {
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char a[10] = "asdf";
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char b[10] = { "asdf" };
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// CHECK: @test4()
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// CHECK: %a = alloca [10 x i8]
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// CHECK: %b = alloca [10 x i8]
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// CHECK: call void @llvm.memcpy
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// CHECK: call void @llvm.memcpy
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}
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union test5u { int i; double d; };
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void test5(void) {
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union test5u ola = (union test5u) 351;
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union test5u olb = (union test5u) 1.0;
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}
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union test5u test5w = (union test5u)2;
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union test5u test5y = (union test5u)73.0;
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// PR6660 - sqlite miscompile
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struct SelectDest {
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unsigned char eDest;
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unsigned char affinity;
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int iParm;
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int iMem;
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};
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void test6(void) {
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struct SelectDest x = {1, 2, 3};
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test6f(&x);
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}
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// rdar://7657600
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struct test7s { int a; int b; } test7[] = {
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{1, 2},
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{4},
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};
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// rdar://7872531
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#pragma pack(push, 2)
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struct test8s { int f0; char f1; } test8g = {};
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// PR7519
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struct S {
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void (*x) (struct S *);
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};
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extern struct S *global_dc;
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void cp_diagnostic_starter(struct S *);
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void init_error(void) {
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global_dc->x = cp_diagnostic_starter;
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}
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// rdar://8147692 - ABI crash in recursive struct-through-function-pointer.
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typedef struct {
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int x5a;
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} x5;
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typedef struct x2 *x0;
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typedef long (*x1)(x0 x0a, x5 x6);
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struct x2 {
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x1 x4;
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};
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long x3(x0 x0a, x5 a) {
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return x0a->x4(x0a, a);
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}
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