Import official C23 code examples for Modern C (Jens Gustedt, 2024)HEADupstream-importmain

- Add official C source files, Makefile, c23-fallback.h, and LICENSE
- Update README.md with study mirror notice

1 files changed, 20 insertions, 0 deletions

diff --git a/shadow.c b/shadow.c
new file mode 100644
index 0000000..f996fc8
--- /dev/null
+++ b/shadow.c
@@ -0,0 +1,20 @@
+#include "c23-fallback.h"
+
+void squareIt(double* p) [[__unsequenced__]] {
+  *p *= *p;
+}
+int main(void) {
+  double x = 35.0; /*@\label{line:decl-x}*/
+  double* xp = &x; /*@\label{line:decl-xp}*/
+  {
+    squareIt(&x);               /* Refers to double x *//*@\label{line:use-x-1}*/
+    /*@…*/
+    [[maybe_unused]] int x = 0; /* Shadow double x *//*@\label{line:decl-x-2}*/
+    /*@…*/
+    squareIt(xp);               /* Valid use of double x *//*@\label{line:use-xp}*/
+    /*@…*/
+  }                /*@\label{line:end-x-2}*/
+  /*@…*/
+  squareIt(&x);                 /* Refers to double x *//*@\label{line:use-x-2}*/
+  /*@…*/
+}