I think the subject line says it all. Looking at : https://gcc.gnu.org/onlinedocs/gcc-13.2.0/gcc/Standards.html#C-Language I see : The original ANSI C standard (X3.159-1989) was ratified in 1989 and published in 1990. This standard was ratified as an ISO standard (ISO/IEC 9899:1990) later in 1990. There were no technical differences between these publications, although the sections of the ANSI standard were renumbered and became clauses in the ISO standard. The ANSI standard, but not the ISO standard, also came with a Rationale document. This standard, in both its forms, is commonly known as C89, or occasionally as C90, from the dates of ratification. To select this standard in GCC, use one of the options -ansi, -std=c90 or -std=iso9899:1990; to obtain all the diagnostics required by the standard, you should also specify -pedantic (or -pedantic-errors if you want them to be errors rather than warnings). See Options Controlling C Dialect. Errors in the 1990 ISO C standard were corrected in two Technical Corrigenda published in 1994 and 1996. GCC does not support the uncorrected version. An amendment to the 1990 standard was published in 1995. This amendment added digraphs and __STDC_VERSION__ to the language, but otherwise concerned the library. This amendment is commonly known as AMD1; the amended standard is sometimes known as C94 or C95. To select this standard in GCC, use the option -std=iso9899:199409 (with, as for other standard versions, -pedantic to receive all required diagnostics). A new edition of the ISO C standard was published in 1999 as ISO/IEC 9899:1999, and is commonly known as C99. (While in development, drafts of this standard version were referred to as C9X.) GCC has substantially complete support for this standard version; see https://gcc.gnu.org/c99status.html for details. To select this standard, use -std=c99 or -std=iso9899:1999. Errors in the 1999 ISO C standard were corrected in three Technical Corrigenda published in 2001, 2004 and 2007. GCC does not support the uncorrected version. A fourth version of the C standard, known as C11, was published in 2011 as ISO/IEC 9899:2011. (While in development, drafts of this standard version were referred to as C1X.) GCC has substantially complete support for this standard, enabled with -std=c11 or -std=iso9899:2011. A version with corrections integrated was prepared in 2017 and published in 2018 as ISO/IEC 9899:2018; it is known as C17 and is supported with -std=c17 or -std=iso9899:2017; the corrections are also applied with -std=c11, and the only difference between the options is the value of __STDC_VERSION__. Looking also at : https://gcc.gnu.org/onlinedocs/gcc-13.2.0/gcc/C-Dialect-Options.html There I see : -std= Determine the language standard. See Language Standards Supported by GCC, for details of these standard versions. This option is currently only supported when compiling C or C++. With some adjustments or tuning flags such as "-Wpedantic" for some nice warnings about GNU extensions. HOWEVER I DO NOT see the flags "-pedantic" nor "-pedantic-errors" there. I see some goodness documented at : https://gcc.gnu.org/onlinedocs/gcc-13.2.0/gcc/Warning-Options.html However that page talks about ANSI C but no mention of something like the C11 std or others. So the question here is : Do the options -pedantic and -pedantic-errors mean anything to the -std=iso9899:2011 C Language spec? -- Dennis Clarke RISC-V/SPARC/PPC/ARM/CISC UNIX and Linux spoken GreyBeard and suspenders optional
