From 82ba818ff456bcd6d56a06226e3f27e98fbb55c3 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Thu, 14 Aug 2025 22:58:58 -0500 Subject: removing all downloaded devdocs files --- devdocs/c/language%2Fattributes%2Fnodiscard.html | 42 ------------------------ 1 file changed, 42 deletions(-) delete mode 100644 devdocs/c/language%2Fattributes%2Fnodiscard.html (limited to 'devdocs/c/language%2Fattributes%2Fnodiscard.html') diff --git a/devdocs/c/language%2Fattributes%2Fnodiscard.html b/devdocs/c/language%2Fattributes%2Fnodiscard.html deleted file mode 100644 index 35c94f7d..00000000 --- a/devdocs/c/language%2Fattributes%2Fnodiscard.html +++ /dev/null @@ -1,42 +0,0 @@ -

C attribute: nodiscard (since C23) -

If a function declared nodiscard or a function returning a struct/union/enum declared nodiscard by value is called from a discarded-value expression other than a cast to void, the compiler is encouraged to issue a warning.

-

Syntax

- - -
[[ nodiscard ]]
[[ __nodiscard__ ]] 		(1)
[[ nodiscard ( string-literal ) ]]
[[ __nodiscard__ ( string-literal ) ]] 		(2)
- -
string-literal - text that could be used to explain the rationale for why the result should not be discarded

Explanation

Appears in a function declaration, enumeration declaration, or struct/union declaration.

-

If, from a discarded-value expression other than a cast to void,

-

the compiler is encouraged to issue a warning.

-

The string-literal, if specified, is usually included in the warnings.

-

Example

struct [[nodiscard]] error_info { int status; /*...*/ };
-struct error_info enable_missile_safety_mode() { /*...*/ return (struct error_info){0}; }
-void launch_missiles() { /*...*/ }
-void test_missiles() {
-   enable_missile_safety_mode(); // compiler may warn on discarding a nodiscard value
-   launch_missiles();
-}
-struct error_info* foo() { static struct error_info e; /*...*/ return &e; }
-void f1() {
-    foo(); // nodiscard type itself is not returned, no warning
-}
-// nodiscard( string-literal ):
-[[nodiscard("PURE FUN")]] int strategic_value(int x, int y) { return x ^ y; }
- 
-int main()
-{
-    strategic_value(4,2); // compiler may warn on discarding a nodiscard value
-    int z = strategic_value(0,0); // OK: return value is not discarded
-    return z;
-}

Possible output:

-
game.cpp:5:4: warning: ignoring return value of function declared with 'nodiscard' attribute
-game.cpp:17:5: warning: ignoring return value of function declared with 'nodiscard' attribute: PURE FUN

See also

-
C++ documentation for nodiscard
-

- © cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
- https://en.cppreference.com/w/c/language/attributes/nodiscard -

-
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