Gcc Preprocessor Error
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message. You would use ‘#error’ inside of #error c preprocessor a conditional that detects a combination of
C Preprocessor Message
parameters which you know the program does not properly support. For gcc #pragma message example, if you know that the program will not run properly on a VAX, you might write #ifdef __vax__ invalid preprocessor command 'warning' #error "Won't work on VAXen. See comments at get_last_object." #endif If you have several configuration parameters that must be set up by the installation in a consistent way, you can use conditionals to detect an inconsistency and report
#error C++
it with ‘#error’. For example, #if !defined(FOO) && defined(BAR) #error "BAR requires FOO." #endif The directive ‘#warning’ is like ‘#error’, but causes the preprocessor to issue a warning and continue preprocessing. The tokens following ‘#warning’ are used as the warning message. You might use ‘#warning’ in obsolete header files, with a message directing the user to the header file which should be used instead. Neither ‘#error’ nor ‘#warning’ macro-expands its argument. Internal whitespace sequences are each replaced with a single space. The line must consist of complete tokens. It is wisest to make the argument of these directives be a single string constant; this avoids problems with apostrophes and the like.
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#warning C++
million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up C preprocessor: expand macro in a #warning up vote 19 down vote favorite 9 I would like to print a https://gcc.gnu.org/onlinedocs/cpp/Diagnostics.html macro value (expand the macro) in the #warning directive. For example, for the code: #define AAA 17 #warning AAA = ??? The desired compile-time output would be warning: AAA = 17 What do I use for ???, or, how do I augment the code? c gcc c-preprocessor share|improve this question edited Nov 2 '14 at 18:56 AstroCB 7,656113261 asked Sep 28 '12 at 9:35 elomage 1,73811015 1 According to the C standard http://stackoverflow.com/questions/12637392/c-preprocessor-expand-macro-in-a-warning from 1999, you only have #error for something like that and it does not expand any macros, it just prints the text literally and causes compilation to stop. What are you trying to achieve with this anyway? –Alexey Frunze Sep 28 '12 at 9:41 I have a hierarchy of many makefiles that define AAA in various ways, depending on the make target parameters. I would like to verify that the definition is correct for the target. And I would not want to create a list of #if AAA = 1 ... #warning "is 1"... –elomage Sep 28 '12 at 9:44 Also, this is for the embedded world with no displays, so I can not easily test the macro value by adding something like printf( #AAA ); and check it at runtime. –elomage Sep 28 '12 at 9:58 So you do #if A == 1\#error A = 1\#elif A == 2\#error A = 2\#endif. –Alexey Frunze Sep 28 '12 at 10:00 @AlexeyFrunze That is exactly what I want to avoid - see my comment above. I may not know all the possible values, or there might be too many of those. –elomage Sep 28 '12 at 10:09 | show 1 more comment 4 Answers 4 active oldest votes up v
tokens Description #error emits tokens to standard error, and increments the assembler error counter, hereby preventing the program from being http://www.atmel.com/webdoc/avrassembler/avrassembler.wb_preprocessor.error.html successfully assembled. #error is specified in the ANSI C standard. #warning http://tigcc.ticalc.org/doc/cpp.html emits tokens to standard error, and increments the assembler warning counter. #warning is not specified in the ANSI C standard, but is commonly implemented in preprocessors such as the GNU C preprocessor. #message emits tokens to standard output, and does not affect c preprocessor assembler error or warning counters. #message is not specified in the ANSI C standard.For all directives, the output will include file name and line number, like normal error and warning messages.tokens is a sequence of preprocessor tokens. Preprocessor macros are expanded except if appearing inside quoted strings (").Example #error "Unsupported part:" __PART_NAME__ gcc preprocessor error PrevUpNextHomeContentsSearchDocumentation HomeAVR AssemblerPrefaceAVR Assembler Known IssuesAVR Assembler Command Line OptionsAssembler sourceAVR Assembler SyntaxAssembler directivesAVR Assembler PreprocessorIntroductionPreprocessor directives#define#undef#ifdef#ifndef#if and #elif#else#endif#error, #warning and #message#include#pragma, general purpose#pragma , AVR part related# (empty directive)OperatorsStringification (#)Concatenation (##)Pre-defined macrosExpressionsInstruction mnemonicsArithmetic and logic instructionsBranch InstructionsData Transfer InstructionsBit and Bit-test InstructionsI/O RegistersInstruction Set Nomenclature:Instructions ADC - Add with Carry ADD - Add without Carry ADIW - Add Immediate to Word AND - Logical AND ANDI - Logical AND with Immediateand ASR - Arithmetic Shift Right BCLR - Bit Clear in SREG BLD - Bit Load from the T Flag in SREG to a Bit in Register. BRBC - Branch if Bit in SREG is Cleared BRBS - Branch if Bit in SREG is Set BRCC - Branch if Carry Cleared BRCS - Branch if Carry Set BREAK - Break BREQ - Branch if Equal BRGE - Branch if Greater or Equal Signed) BRHC - Branch if Half Carry Flag is Cleared BRHS - B
the C compiler to transform your program before actual compilation. It is called a macro processor because it allows you to define macros, which are brief abbreviations for longer constructs. Preprocessor Overview Header Files Macros Conditionals Pragmas Other Directives User-defined Diagnostics Line Control Preprocessor Output C Preprocessor Command-Line Options Traditional Mode Implementation Details History GNU General Public License GNU Free Documentation License Funding Free Software Original author: Free Software Foundation, Inc. Authors of the modifications: Zeljko Juric, Sebastian Reichelt, and Kevin Kofler Published by the TIGCC Team. See the History section for details and copyright information. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation. A copy of the license is included in the section entitled "GNU Free Documentation License". This manual contains no Invariant Sections. The Front-Cover Texts are (a) (see below), and the Back-Cover Texts are (b) (see below). (a) The FSF's Front-Cover Text is: A GNU Manual (b) The FSF's Back-Cover Text is: You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development. Preprocessor Overview The C preprocessor, often known as cpp, is a macro processor that is used automatically by the C compiler to transform your program before compilation. It is called a macro processor because it allows you to define macros, which are brief abbreviations for longer constructs. The C preprocessor is intended to be used only with C, C++, and Objective-C source code. In the past, it has been abused as a general text processor. It will choke on input which does not obey C's lexical rules. For example, apostrophes will be interpreted as the beginning of chara