microsoft / microsoft/vscode-cpptools
gcc 14.1+ and clang 15+ with gcc/clang no-implicit-function-declaration isn't enforced as an error
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@sean-mcmanus is already working on this.
Since Apr 13, 2026.
bug
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Description
While it's not valid in the C99 standard, it looks like all the C compilers we support don't support this rule, I assume because it would be a breaking change with C89.
In GCC, implicit function declaration is an error even without any additional warning flags. This is with
--std=c23; I'm not sure about C89. You have to explicitly turn this off with-Wno-implicit-function-declaration.
Originally posted by @cD1rtX3 in #828
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