Can't build on Ubuntu 24.10: binding generation fails

[mororo18]

bindgen fails to generate the bindings due of memcpy begin undeclared in stb_dxt.h:

   Compiling stb-sys v0.6.0 (/home/victor/repos/stb/stb-sys)
error: failed to run custom build command for `stb-sys v0.6.0 (/home/victor/repos/stb/stb-sys)`

Caused by:
  process didn't exit successfully: `/home/victor/repos/stb/target/debug/build/stb-sys-664a37f75d337bdc/build-script-build` (exit status: 101)
  --- stderr
  ./src/../vendor/stb/stb_dxt.h:608:7: error: call to undeclared library function 'memcpy' with type 'void *(void *, const void *, unsigned long)'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
  ./src/../vendor/stb/stb_dxt.h:608:7: note: include the header <string.h> or explicitly provide a declaration for 'memcpy'
  ./src/../vendor/stb/stb_dxt.h:608:7: error: call to undeclared library function 'memcpy' with type 'void *(void *, const void *, unsigned long)'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration], err: true
  thread 'main' panicked at stb-sys/build.rs:40:10:
  Failed to generate bindings: ()
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Even after upgrading bindgen to the latest version, the generation still fails. However, this time the error returns a ClangDiagnostic related to memcpy not being declared:

   Compiling stb-sys v0.6.0 (/home/victor/repos/stb/stb-sys)
error: failed to run custom build command for `stb-sys v0.6.0 (/home/victor/repos/stb/stb-sys)`

Caused by:
  process didn't exit successfully: `/home/victor/repos/stb/target/debug/build/stb-sys-1a4a25a1890304b6/build-script-build` (exit status: 101)
  --- stderr
  ./src/../vendor/stb/stb_dxt.h:608:7: error: call to undeclared library function 'memcpy' with type 'void *(void *, const void *, unsigned long)'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
  ./src/../vendor/stb/stb_dxt.h:608:7: note: include the header <string.h> or explicitly provide a declaration for 'memcpy'
  thread 'main' panicked at stb-sys/build.rs:40:10:
  Failed to generate bindings: ClangDiagnostic("./src/../vendor/stb/stb_dxt.h:608:7: error: call to undeclared library function 'memcpy' with type 'void *(void *, const void *, unsigned long)'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]\n")
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

To work around this, I changed the order in which headers are added to the bindgen builder:

diff --git a/stb-sys/build.rs b/stb-sys/build.rs
index c891f30..cecba91 100644
--- a/stb-sys/build.rs
+++ b/stb-sys/build.rs
@@ -4,10 +4,10 @@ use std::path::PathBuf;
 static FILES: &[&str] = &[
     #[cfg(feature = "stb_easy_font")]
     "src/stb_easy_font.c",
-    #[cfg(feature = "stb_dxt")]
-    "src/stb_dxt.c",
     #[cfg(feature = "stb_image")]
     "src/stb_image.c",
+    #[cfg(feature = "stb_dxt")]
+    "src/stb_dxt.c",
     #[cfg(feature = "stb_image_write")]
     "src/stb_image_write.c",
     #[cfg(feature = "stb_rect_pack")]

with this change, the bindings generation works, but the compilation still fails for the same reason.

   Compiling stb-sys v0.6.0 (/home/victor/repos/stb/stb-sys)
The following warnings were emitted during compilation:

warning: stb-sys@0.6.0: In file included from src/stb_dxt.c:2:
warning: stb-sys@0.6.0: src/../vendor/stb/stb_dxt.h: In function 'stb_compress_dxt_block':
warning: stb-sys@0.6.0: src/../vendor/stb/stb_dxt.h:608:7: error: implicit declaration of function 'memcpy' [-Wimplicit-function-declaration]
warning: stb-sys@0.6.0:   608 |       memcpy(data, src, 4*16);
warning: stb-sys@0.6.0:       |       ^~~~~~
warning: stb-sys@0.6.0: src/../vendor/stb/stb_dxt.h:89:1: note: include '<string.h>' or provide a declaration of 'memcpy'
warning: stb-sys@0.6.0:    88 | #include <math.h>
warning: stb-sys@0.6.0:   +++ |+#include <string.h>
warning: stb-sys@0.6.0:    89 | #endif
warning: stb-sys@0.6.0: src/../vendor/stb/stb_dxt.h:608:7: warning: incompatible implicit declaration of built-in function 'memcpy' [-Wbuiltin-declaration-mismatch]
warning: stb-sys@0.6.0:   608 |       memcpy(data, src, 4*16);
warning: stb-sys@0.6.0:       |       ^~~~~~
warning: stb-sys@0.6.0: src/../vendor/stb/stb_dxt.h:608:7: note: include '<string.h>' or provide a declaration of 'memcpy'

error: failed to run custom build command for `stb-sys v0.6.0 (/home/victor/repos/stb/stb-sys)`

Caused by:
  process didn't exit successfully: `/home/victor/repos/stb/target/debug/build/stb-sys-1a4a25a1890304b6/build-script-build` (exit status: 1)
  --- stdout
  OUT_DIR = Some(/home/victor/repos/stb/target/debug/build/stb-sys-3f0f7332534016a8/out)
  OPT_LEVEL = Some(0)
  TARGET = Some(x86_64-unknown-linux-gnu)
  HOST = Some(x86_64-unknown-linux-gnu)
  cargo:rerun-if-env-changed=CC_x86_64-unknown-linux-gnu
  CC_x86_64-unknown-linux-gnu = None
  cargo:rerun-if-env-changed=CC_x86_64_unknown_linux_gnu
  CC_x86_64_unknown_linux_gnu = None
  cargo:rerun-if-env-changed=HOST_CC
  HOST_CC = None
  cargo:rerun-if-env-changed=CC
  CC = None
  cargo:rerun-if-env-changed=CC_ENABLE_DEBUG_OUTPUT
  RUSTC_WRAPPER = None
  cargo:rerun-if-env-changed=CRATE_CC_NO_DEFAULTS
  CRATE_CC_NO_DEFAULTS = None
  DEBUG = Some(true)
  CARGO_CFG_TARGET_FEATURE = Some(fxsr,sse,sse2)
  cargo:rerun-if-env-changed=CFLAGS_x86_64-unknown-linux-gnu
  CFLAGS_x86_64-unknown-linux-gnu = None
  cargo:rerun-if-env-changed=CFLAGS_x86_64_unknown_linux_gnu
  CFLAGS_x86_64_unknown_linux_gnu = None
  cargo:rerun-if-env-changed=HOST_CFLAGS
  HOST_CFLAGS = None
  cargo:rerun-if-env-changed=CFLAGS
  CFLAGS = None
  CARGO_ENCODED_RUSTFLAGS = Some()
  cargo:warning=In file included from src/stb_dxt.c:2:
  cargo:warning=src/../vendor/stb/stb_dxt.h: In function 'stb_compress_dxt_block':
  cargo:warning=src/../vendor/stb/stb_dxt.h:608:7: error: implicit declaration of function 'memcpy' [-Wimplicit-function-declaration]
  cargo:warning=  608 |       memcpy(data, src, 4*16);
  cargo:warning=      |       ^~~~~~
  cargo:warning=src/../vendor/stb/stb_dxt.h:89:1: note: include '<string.h>' or provide a declaration of 'memcpy'
  cargo:warning=   88 | #include <math.h>
  cargo:warning=  +++ |+#include <string.h>
  cargo:warning=   89 | #endif
  cargo:warning=src/../vendor/stb/stb_dxt.h:608:7: warning: incompatible implicit declaration of built-in function 'memcpy' [-Wbuiltin-declaration-mismatch]
  cargo:warning=  608 |       memcpy(data, src, 4*16);
  cargo:warning=      |       ^~~~~~
  cargo:warning=src/../vendor/stb/stb_dxt.h:608:7: note: include '<string.h>' or provide a declaration of 'memcpy'

  --- stderr


  error occurred in cc-rs: Command LC_ALL="C" "cc" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-o" "/home/victor/repos/stb/target/debug/build/stb-sys-3f0f7332534016a8/out/ea708c7824d36062-stb_dxt.o" "-c" "src/stb_dxt.c" with args cc did not execute successfully (status code exit status: 1).

Finally, the build works when using clang-14 as the compiler, but still fails with clang-19:

$ CC=clang-14 cargo build
   Compiling stb-sys v0.6.0 (/home/victor/repos/stb/stb-sys)
warning: stb-sys@0.6.0: In file included from src/stb_dxt.c:2:
warning: stb-sys@0.6.0: src/../vendor/stb/stb_dxt.h:608:7: warning: implicitly declaring library function 'memcpy' with type 'void *(void *, const void *, unsigned long)' [-Wimplicit-function-declaration]
warning: stb-sys@0.6.0:       memcpy(data, src, 4*16);
warning: stb-sys@0.6.0:       ^
warning: stb-sys@0.6.0: src/../vendor/stb/stb_dxt.h:608:7: note: include the header <string.h> or explicitly provide a declaration for 'memcpy'
warning: stb-sys@0.6.0: 1 warning generated.
   Compiling stb v0.3.2 (/home/victor/repos/stb/stb)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 4.81s

If I only include the header <string.h> in stb-sys/src/stb_dxt.c, without upgrading bindgen, the generation still fails:

   Compiling stb-sys v0.6.0 (/home/victor/repos/stb/stb-sys)
error: failed to run custom build command for `stb-sys v0.6.0 (/home/victor/repos/stb/stb-sys)`

Caused by:
  process didn't exit successfully: `/home/victor/repos/stb/target/debug/build/stb-sys-664a37f75d337bdc/build-script-build` (exit status: 101)
  --- stderr
  thread 'main' panicked at /home/victor/.cargo/registry/src/index.crates.io-6f17d22bba15001f/bindgen-0.54.0/src/ir/ty.rs:1165:22:
  Not able to resolve vector element?: Continue
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace