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Gcc Error Warning Preprocessor

For example, knowing that a branch is taken very frequently helps the compiler make better decisions when ordering basic blocks. The preprocessor backslash-escapes the quotes surrounding embedded string constants, and all backslashes within string and character constants, in order to get a valid C string constant with the proper contents. You can put as much whitespace between ## and its operands as you like, including comments, and you can put comments in arguments that will be concatenated. CPP searches for the file according to the rules for angle-bracket includes.

What do I do when two squares are equally valid? A categorization of the diagnostic as a note, warning, error, or fatal error. In either case, backslash is an ordinary character. The Inline stack is a stack of source locations in which the top of the stack represents the leaf function, and the bottom of the stack represents the actual symbol to https://gcc.gnu.org/onlinedocs/cpp/Diagnostics.html

Example: #define DECLARE_STRUCT_TYPE(name) typedef struct name##_s name##_t DECLARE_STRUCT_TYPE(g_object); // Outputs: typedef struct g_object_s g_object_t; User-defined compilation errors[edit] The #error directive outputs a message through the error stream. #error "error message" Implementations[edit] Programs cannot define new preprocessing directives. Example: #define str(s) #s str(p = "foo\n";) // outputs "p = \"foo\\n\";" str(\n) // outputs "\n" If you want to stringify the expansion of a macro argument, you have to use If all you need to know is whether or not your program is being compiled by GCC, you can simply test __GNUC__.

However, historically system-specific macros have had names with no special prefix; for instance, it is common to find On-line Guides All Guides eBook Store iOS / Android Linux for Beginners Office In this case the C99 standard is clear that the comma must remain, however the existing GCC extension used to swallow the comma. Controlling Debug Information¶ Controlling Size of Debug Information¶ Debug info kind generated by Clang can be set by one of the flags listed below. more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed

In a user header file, the macro name should not begin with _. When Clang emits a dependency file (e.g., you supplied the -M option) most filenames can be written to the file without any special formatting. You create macros with the #define directive. #define is followed by the name of the macro and then the token sequence it should be an abbreviation for, which is variously referred more info here Note that the WHERESTR argument is concatenated with the string following it.

See Differences from previous versions. Join them; it only takes a minute: Sign up Portability of #warning preprocessor directive up vote 38 down vote favorite 2 I know that the #warning directive is not standard C/C++, This is called token pasting or token concatenation. If GCC cannot determine the current time, it will emit a warning message (once per compilation) and __TIME__ will expand to "??:??:??". __STDC__ In normal operation, this macro expands to the

All leading and trailing whitespace in text being stringified is ignored. The new definition need not have any resemblance to the old definition. You could include the old header with an absolute pathname: #include "/usr/include/old-header.h" This works, but is not clean; should the system headers ever move, you would have to edit the new The compiler does not re-tokenize the preprocessor's output.

If you write just the name, it is left alone. A hosted environment has the complete facilities of the standard C library available. The file name pattern specified can include different modifiers: %p, %h, and %m. The C standard requires that all system-specific macros be part of the reserved namespace.

How do you say #warning to Visual Studio? This is the format generated by the create_llvm_prof tool in http://github.com/google/autofdo. If whitespace is present, the macro will be interpreted as object-like with everything starting from the first parenthesis added to the token list. GCC does not presently implement either feature in the preprocessor or the compiler.

I replaced the link with one to gcc doc. –philant Nov 17 '15 at 17:29 add a comment| up vote 4 down vote You can use a error directive for that. Header file names either look like string constants, "...", or are written with angle brackets instead, <...>. Dr.

Authors of the modifications: Zeljko Juric, Sebastian Reichelt, and Kevin Kofler Published by the TIGCC Team.

They are only meant to implement GCC's semantics with respect to profile creation and use. -fprofile-generate[=]¶ The -fprofile-generate and -fprofile-generate= flags will use an alterantive instrumentation method for profile You can happily write #warning in C#, but not C++.Interestingly, the answer fell below my Google/Boredom Threshold (i.e. You should not refer to this macro yourself; instead, refer to the standard macros defined in limits.h. __SCHAR_MAX__, __SHRT_MAX__, __INT_MAX__, __LONG_MAX__, __LONG_LONG_MAX__ Defined to the maximum value of the signed

Macro definitions take effect at the place you write them. Previous GNU preprocessor implementations and documentation were incorrect on this point, insisting that a function-like macro that takes a single argument be passed a space if an empty argument was required. In the 1999 C standard, identifiers may contain letters which are not part of the "basic source character set," at the implementation's discretion (such as accented Latin letters, Greek letters, or Macro expansion.

These include __FILE__ and __LINE__, predefined by the preprocessor itself, which expand into the current file and line number. Default: t.cc:4:5: note: candidate function not viable: no known conversion from 'vector>>' to 'vector>>' for 1st argument; With -fdiagnostics-show-template-tree: t.cc:4:5: note: candidate function not viable: no The values of __FILE__ and __LINE__ can be manipulated with the #line directive. It will choke on input which does not obey C's lexical rules.

The format is described below. This is useful when working with 3rd-party libraries that don't come with debug information. Thus, stringifying p="foo\n"; results in "p=\"foo\\n\";". Other Options¶ Clang options that that don't fit neatly into other categories. -MV¶ When emitting a dependency file, use formatting conventions appropriate for NMake or Jom.

The include file is then referenced repeatedly.