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Introduction
GNU extensions
The compiler supports some extensions offered by the GNU
compiler, for example, GNU-style extended lvalues and GNU
builtin functions. For more information see:
• Language compliance
• GNU language extensions on page 3-25
• Chapter 4 Compiler-specific Features.
1.3.2 Language compliance
ARM-specific extensions
The compiler supports a range of extensions specific to the ARM
compiler, for example, instruction intrinsics and other builtin
functions. See Chapter 4 Compiler-specific Features for more
information.
The compiler has several modes where compliance to a source language is either
enforced or relaxed:
Strict mode In strict mode the compiler enforces compliance with the language
standard relevant to the source language. For example, the use of //-style
comments results in an error when compiling strict C90.
To compile in strict mode, use the command-line option --strict.
GNU mode In GNU mode all the GNU compiler extensions to the relevant source
language are available. For example, in GNU mode:
• case ranges in switch statements are available when the source
language is any of C90, C99 or nonstrict C++
• C99-style designated initializers are available when the source
language is either C90 or nonstrict C++.
To compile in GNU mode, use the compiler option --gnu.
Note
Some GNU extensions are also available when you are in a nonstrict
mode.
Example
The following examples illustrate combining source language modes with language
compliance modes:
• Compiling a .cpp file with the command-line option --strict compiles Standard
C++
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