Traditionally, diagnostic messages have been formatted irrespective of the output device's aspect (e.g. its width, ...). You can use the options described below to control the formatting algorithm for diagnostic messages, e.g. how many characters per line, how often source location information should be reported. Note that some language front ends may not honor these options.
-fmessage-length=
n
-fdiagnostics-show-location=once
-fdiagnostics-show-location=every-line
-fdiagnostics-color[=
WHEN]
-fno-diagnostics-color
never
’, ‘always
’, or ‘auto
’. The default depends on how the compiler has been configured, it can be any of the above WHEN options or also ‘never
’ if GCC_COLORS
environment variable isn't present in the environment, and ‘auto
’ otherwise. ‘auto
’ means to use color only when the standard error is a terminal. The forms -fdiagnostics-color
and -fno-diagnostics-color
are aliases for -fdiagnostics-color=always
and -fdiagnostics-color=never
, respectively. The colors are defined by the environment variable GCC_COLORS
. Its value is a colon-separated list of capabilities and Select Graphic Rendition (SGR) substrings. SGR commands are interpreted by the terminal or terminal emulator. (See the section in the documentation of your text terminal for permitted values and their meanings as character attributes.) These substring values are integers in decimal representation and can be concatenated with semicolons. Common values to concatenate include ‘1
’ for bold, ‘4
’ for underline, ‘5
’ for blink, ‘7
’ for inverse, ‘39
’ for default foreground color, ‘30
’ to ‘37
’ for foreground colors, ‘90
’ to ‘97
’ for 16-color mode foreground colors, ‘38;5;0
’ to ‘38;5;255
’ for 88-color and 256-color modes foreground colors, ‘49
’ for default background color, ‘40
’ to ‘47
’ for background colors, ‘100
’ to ‘107
’ for 16-color mode background colors, and ‘48;5;0
’ to ‘48;5;255
’ for 88-color and 256-color modes background colors.
The default GCC_COLORS
is
error=01;31:warning=01;35:note=01;36:caret=01;32:locus=01:quote=01
where ‘01;31
’ is bold red, ‘01;35
’ is bold magenta, ‘01;36
’ is bold cyan, ‘01;32
’ is bold green and ‘01
’ is bold. Setting GCC_COLORS
to the empty string disables colors. Supported capabilities are as follows.
error=
warning=
note=
caret=
locus=
file:line
’ or ‘file:line:column
’ etc. quote=
-fno-diagnostics-show-option
-fno-diagnostics-show-option
flag suppresses that behavior. -fno-diagnostics-show-caret
^
’ indicating the column. This option suppresses this information. The source line is truncated to n characters, if the -fmessage-length=n
option is given. When the output is done to the terminal, the width is limited to the width given by the COLUMNS
environment variable or, if not set, to the terminal width.
© Free Software Foundation
Licensed under the GNU Free Documentation License, Version 1.3.
https://gcc.gnu.org/onlinedocs/gcc-6.3.0/gcc/Diagnostic-Message-Formatting-Options.html