Tested x86_64-pc-linux-gnu, applying to trunk. -- 8< --
The C++ standard specifies that the <string.h> functions have const and non-const overloads, unlike C's single function with const argument and non-const return. Many systems don't actually implement this, but only add an overload with non-const argument, so both end up having non-const return. Solaris <string.h> does what the standard says, but we were penalizing it by not recognizing the const overload as the built-in memchr. PR c++/113706 gcc/cp/ChangeLog: * decl.cc (decls_match): Handle memchr return type being const-qualified. gcc/testsuite/ChangeLog: * g++.dg/opt/const-builtin1.C: New test. * c-c++-common/pr103798-2.c: Remove xfail. --- gcc/cp/decl.cc | 10 +++++++ gcc/testsuite/c-c++-common/pr103798-2.c | 3 +-- gcc/testsuite/g++.dg/opt/const-builtin1.C | 33 +++++++++++++++++++++++ 3 files changed, 44 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/g++.dg/opt/const-builtin1.C diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc index d88e0698652..df855334133 100644 --- a/gcc/cp/decl.cc +++ b/gcc/cp/decl.cc @@ -1156,6 +1156,16 @@ decls_match (tree newdecl, tree olddecl, bool record_versions /* = true */) tree r2 = fndecl_declared_return_type (olddecl); tree r1 = fndecl_declared_return_type (newdecl); + /* For memchr et al, allow const void* return type (as specified by C++) + when we expect void* (as in C). */ + if (DECL_IS_UNDECLARED_BUILTIN (olddecl) + && DECL_EXTERN_C_P (olddecl) + && !same_type_p (r1, r2) + && TREE_CODE (r1) == POINTER_TYPE + && TREE_CODE (r2) == POINTER_TYPE + && comp_ptr_ttypes (TREE_TYPE (r1), TREE_TYPE (r2))) + r2 = r1; + tree p1 = TYPE_ARG_TYPES (f1); tree p2 = TYPE_ARG_TYPES (f2); diff --git a/gcc/testsuite/c-c++-common/pr103798-2.c b/gcc/testsuite/c-c++-common/pr103798-2.c index 83cdfaa1660..e7e99c3679e 100644 --- a/gcc/testsuite/c-c++-common/pr103798-2.c +++ b/gcc/testsuite/c-c++-common/pr103798-2.c @@ -27,5 +27,4 @@ main () return 0; } -/* See PR c++/113706 for the xfail. */ -/* { dg-final { scan-assembler-not "memchr" { xfail { c++ && { *-*-solaris2* *-*-vxworks* } } } } } */ +/* { dg-final { scan-assembler-not "memchr" } } */ diff --git a/gcc/testsuite/g++.dg/opt/const-builtin1.C b/gcc/testsuite/g++.dg/opt/const-builtin1.C new file mode 100644 index 00000000000..8b9987271c0 --- /dev/null +++ b/gcc/testsuite/g++.dg/opt/const-builtin1.C @@ -0,0 +1,33 @@ +// PR c++/113706 +/* A variant of the pr103798-2.c test with const void * memchr return type, as + specified by the C++ standard. */ +/* { dg-do run } */ +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */ + +extern "C" const void *memchr (const void *, int, __SIZE_TYPE__); // { dg-bogus "built-in" } + +__attribute__ ((weak)) +int +f (int a) +{ + return memchr ("aE", a, 2) != 0; +} + +__attribute__ ((weak)) +int +g (char a) +{ + return a == 'a' || a == 'E'; +} + +int +main () +{ + for (int i = 0; i < 255; i++) + if (f (i + 256) != g (i + 256)) + __builtin_abort (); + + return 0; +} + +/* { dg-final { scan-assembler-not "memchr" } } */ base-commit: c60b3e211c555706cdc2dc8bfcdd540152cff350 -- 2.44.0