Add new option, -Wreserved-user-defined-literal. This option, which is enabled by default, causes the preprocessor to warn when a string or character literal is followed by a ud-suffix which does not begin with an underscore. According to [lex.ext]p10, this is ill-formed.
Also modifies the preprocessor to treat such ill-formed suffixes as separate preprocessing tokens. This is consistent with the Clang front end (see http://llvm.org/viewvc/llvm-project?view=rev&revision=152287), and enables backwards compatibility with code that uses formatting macros from <inttypes.h>, as in the following code block: int main() { int64_t i64 = 123; printf("My int64: %"PRId64"\n", i64); } Google ref b/6377711. 2012-04-22 Ollie Wild <a...@google.com> * gcc/c-family/c-common.c: * gcc/c-family/c-opts.c (c_common_handle_option): * gcc/c-family/c.opt: * gcc/doc/invoke.texi (struct A): * gcc/testsuite/g++.dg/cpp0x/Wreserved-user-defined-literal.C (test): (main): * libcpp/include/cpplib.h (struct cpp_options): * libcpp/init.c (cpp_create_reader): * libcpp/lex.c (lex_raw_string): (lex_string): diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c index 1d19251..915dc25 100644 --- a/gcc/c-family/c-common.c +++ b/gcc/c-family/c-common.c @@ -8724,6 +8724,7 @@ static const struct reason_option_codes_t option_codes[] = { {CPP_W_NORMALIZE, OPT_Wnormalized_}, {CPP_W_INVALID_PCH, OPT_Winvalid_pch}, {CPP_W_WARNING_DIRECTIVE, OPT_Wcpp}, + {CPP_W_RESERVED_USER_LITERALS, OPT_Wreserved_user_defined_literal}, {CPP_W_NONE, 0} }; diff --git a/gcc/c-family/c-opts.c b/gcc/c-family/c-opts.c index 5118928..dab6ce5 100644 --- a/gcc/c-family/c-opts.c +++ b/gcc/c-family/c-opts.c @@ -509,6 +509,10 @@ c_common_handle_option (size_t scode, const char *arg, int value, break; } + case OPT_Wreserved_user_defined_literal: + cpp_opts->warn_reserved_user_literals = value; + break; + case OPT_Wreturn_type: warn_return_type = value; break; diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt index 40ff96c..f610513 100644 --- a/gcc/c-family/c.opt +++ b/gcc/c-family/c.opt @@ -589,6 +589,10 @@ Wreorder C++ ObjC++ Var(warn_reorder) Warning Warn when the compiler reorders code +Wreserved-user-defined-literal +C++ ObjC++ Warning +Warn when a string or character literal is followed by a ud-suffix which does not begin with an underscore. + Wreturn-type C ObjC C++ ObjC++ Var(warn_return_type) Warning Warn whenever a function's return type defaults to \"int\" (C), or about inconsistent return types (C++) diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 1b61e76..d425079 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -198,7 +198,7 @@ in the following sections. -fvisibility-ms-compat @gol -Wabi -Wconversion-null -Wctor-dtor-privacy @gol -Wdelete-non-virtual-dtor -Wnarrowing -Wnoexcept @gol --Wnon-virtual-dtor -Wreorder @gol +-Wnon-virtual-dtor -Wreorder -Wreserved-user-defined-literal @gol -Weffc++ -Wstrict-null-sentinel @gol -Wno-non-template-friend -Wold-style-cast @gol -Woverloaded-virtual -Wno-pmf-conversions @gol @@ -2474,6 +2474,30 @@ struct A @{ The compiler will rearrange the member initializers for @samp{i} and @samp{j} to match the declaration order of the members, emitting a warning to that effect. This warning is enabled by @option{-Wall}. + +@item -Wreserved-user-defined-literal @r{(C++ and Objective-C++ only)} +@opindex Wreserved-user-defined-literal +@opindex Wno-reserved-user-defined-literal +Warn when a string or character literal is followed by a ud-suffix which does +not begin with an underscore. As a conforming extension, GCC treats such +suffixes as separate preprocessing tokens in order to maintain backwards +compatibility with code that uses formatting macros from @code{<inttypes.h>}. +For example: + +@smallexample +#define __STDC_FORMAT_MACROS +#include <inttypes.h> +#include <stdio.h> + +int main() @{ + int64_t i64 = 123; + printf("My int64: %"PRId64"\n", i64); +@} +@end smallexample + +In this case, @code{PRId64} is treated as a separate preprocessing token. + +This warning is enabled by default. @end table The following @option{-W@dots{}} options are not affected by @option{-Wall}. diff --git a/gcc/testsuite/g++.dg/cpp0x/Wreserved-user-defined-literal.C b/gcc/testsuite/g++.dg/cpp0x/Wreserved-user-defined-literal.C new file mode 100644 index 0000000..66de5c0 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/Wreserved-user-defined-literal.C @@ -0,0 +1,29 @@ +// { dg-do run } +// { dg-options "-std=c++0x" } + +// Make sure -Wreserved-user-defined-literal is enabled by default and +// triggers as expected. + +#define BAR "bar" +#define PLUS_ONE + 1 + +#include <cstdint> +#include <cassert> + + +void +test() +{ + char c = '3'PLUS_ONE; // { dg-warning "invalid suffix on literal" } + char s[] = "foo"BAR; // { dg-warning "invalid suffix on literal" } + + assert(c == '4'); + assert(s[3] != '\0'); + assert(s[3] == 'b'); +} + +int +main() +{ + test(); +} diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h index bf59d01..84cacb0 100644 --- a/libcpp/include/cpplib.h +++ b/libcpp/include/cpplib.h @@ -427,6 +427,10 @@ struct cpp_options /* Nonzero for C++ 2011 Standard user-defnied literals. */ unsigned char user_literals; + /* Nonzero means warn when a string or character literal is followed by a + ud-suffix which does not beging with an underscore. */ + unsigned char warn_reserved_user_literals; + /* Holds the name of the target (execution) character set. */ const char *narrow_charset; @@ -906,7 +910,8 @@ enum { CPP_W_CXX_OPERATOR_NAMES, CPP_W_NORMALIZE, CPP_W_INVALID_PCH, - CPP_W_WARNING_DIRECTIVE + CPP_W_WARNING_DIRECTIVE, + CPP_W_RESERVED_USER_LITERALS }; /* Output a diagnostic of some kind. */ diff --git a/libcpp/init.c b/libcpp/init.c index 5fa82ca..2688699 100644 --- a/libcpp/init.c +++ b/libcpp/init.c @@ -175,6 +175,7 @@ cpp_create_reader (enum c_lang lang, hash_table *table, CPP_OPTION (pfile, warn_variadic_macros) = 1; CPP_OPTION (pfile, warn_builtin_macro_redefined) = 1; CPP_OPTION (pfile, warn_normalize) = normalized_C; + CPP_OPTION (pfile, warn_reserved_user_literals) = 1; /* Default CPP arithmetic to something sensible for the host for the benefit of dumb users like fix-header. */ diff --git a/libcpp/lex.c b/libcpp/lex.c index 0ad9660..ba8ed9e 100644 --- a/libcpp/lex.c +++ b/libcpp/lex.c @@ -1491,14 +1491,30 @@ lex_raw_string (cpp_reader *pfile, cpp_token *token, const uchar *base, if (CPP_OPTION (pfile, user_literals)) { + /* According to C++11 [lex.ext]p10, a ud-suffix not starting with an + underscore is ill-formed. Since this breaks programs using macros + from inttypes.h, we generate a warning and treat the ud-suffix as a + separate preprocessing token. This approach is under discussion by + the standards committee, and has been adopted as a conforming + extension by other front ends such as clang. */ + if (ISALPHA(*cur)) + { + // Raise a warning, but do not consume subsequent tokens. + if (CPP_OPTION (pfile, warn_reserved_user_literals)) + cpp_warning_with_line (pfile, CPP_W_RESERVED_USER_LITERALS, + token->src_loc, 0, + "invalid suffix on literal; C++11 requires " + "a space between literal and identifier"); + } /* Grab user defined literal suffix. */ - if (ISIDST (*cur)) + else if (*cur == '_') { type = cpp_userdef_string_add_type (type); ++cur; + + while (ISIDNUM (*cur)) + ++cur; } - while (ISIDNUM (*cur)) - ++cur; } pfile->buffer->cur = cur; @@ -1606,15 +1622,31 @@ lex_string (cpp_reader *pfile, cpp_token *token, const uchar *base) if (CPP_OPTION (pfile, user_literals)) { + /* According to C++11 [lex.ext]p10, a ud-suffix not starting with an + underscore is ill-formed. Since this breaks programs using macros + from inttypes.h, we generate a warning and treat the ud-suffix as a + separate preprocessing token. This approach is under discussion by + the standards committee, and has been adopted as a conforming + extension by other front ends such as clang. */ + if (ISALPHA(*cur)) + { + // Raise a warning, but do not consume subsequent tokens. + if (CPP_OPTION (pfile, warn_reserved_user_literals)) + cpp_warning_with_line (pfile, CPP_W_RESERVED_USER_LITERALS, + token->src_loc, 0, + "invalid suffix on literal; C++11 requires " + "a space between literal and identifier"); + } /* Grab user defined literal suffix. */ - if (ISIDST (*cur)) + else if (*cur == '_') { type = cpp_userdef_char_add_type (type); type = cpp_userdef_string_add_type (type); ++cur; + + while (ISIDNUM (*cur)) + ++cur; } - while (ISIDNUM (*cur)) - ++cur; } pfile->buffer->cur = cur; -- This patch is available for review at http://codereview.appspot.com/6104051
