diff --git a/library/core/src/ffi/mod.rs b/library/core/src/ffi/mod.rs
index 5f32775822be6..2ba4370c7b7ee 100644
--- a/library/core/src/ffi/mod.rs
+++ b/library/core/src/ffi/mod.rs
@@ -66,7 +66,7 @@ type_alias! { "c_longlong.md", c_longlong = i64; }
 type_alias! { "c_ulonglong.md", c_ulonglong = u64; }
 
 type_alias! { "c_float.md", c_float = f32; }
-type_alias! { "c_double.md", c_double = f64; }
+type_alias! { "c_double.md", c_double = c_double_definition::c_double; #[doc(cfg(all()))]}
 
 /// Equivalent to C's `size_t` type, from `stddef.h` (or `cstddef` for C++).
 ///
@@ -205,6 +205,16 @@ mod c_long_definition {
     }
 }
 
+mod c_double_definition {
+    cfg_if! {
+        if #[cfg(all(target_arch = "avr"))] {
+            pub type c_double = f32;
+        } else {
+            pub type c_double = f64;
+        }
+    }
+}
+
 // N.B., for LLVM to recognize the void pointer type and by extension
 //     functions like malloc(), we need to have it represented as i8* in
 //     LLVM bitcode. The enum used here ensures this and prevents misuse
diff --git a/tests/auxiliary/minicore.rs b/tests/auxiliary/minicore.rs
index a68552175c318..34f78f48ac593 100644
--- a/tests/auxiliary/minicore.rs
+++ b/tests/auxiliary/minicore.rs
@@ -108,3 +108,127 @@ macro_rules! stringify {
         /* compiler built-in */
     };
 }
+
+macro_rules! cfg_if {
+    // match if/else chains with a final `else`
+    (
+        $(
+            if #[cfg( $i_meta:meta )] { $( $i_tokens:tt )* }
+        ) else+
+        else { $( $e_tokens:tt )* }
+    ) => {
+        cfg_if! {
+            @__items () ;
+            $(
+                (( $i_meta ) ( $( $i_tokens )* )) ,
+            )+
+            (() ( $( $e_tokens )* )) ,
+        }
+    };
+
+    // Internal and recursive macro to emit all the items
+    //
+    // Collects all the previous cfgs in a list at the beginning, so they can be
+    // negated. After the semicolon is all the remaining items.
+    (@__items ( $( $_:meta , )* ) ; ) => {};
+    (
+        @__items ( $( $no:meta , )* ) ;
+        (( $( $yes:meta )? ) ( $( $tokens:tt )* )) ,
+        $( $rest:tt , )*
+    ) => {
+        // Emit all items within one block, applying an appropriate #[cfg]. The
+        // #[cfg] will require all `$yes` matchers specified and must also negate
+        // all previous matchers.
+        #[cfg(all(
+            $( $yes , )?
+            not(any( $( $no ),* ))
+        ))]
+        cfg_if! { @__identity $( $tokens )* }
+
+        // Recurse to emit all other items in `$rest`, and when we do so add all
+        // our `$yes` matchers to the list of `$no` matchers as future emissions
+        // will have to negate everything we just matched as well.
+        cfg_if! {
+            @__items ( $( $no , )* $( $yes , )? ) ;
+            $( $rest , )*
+        }
+    };
+
+    // Internal macro to make __apply work out right for different match types,
+    // because of how macros match/expand stuff.
+    (@__identity $( $tokens:tt )* ) => {
+        $( $tokens )*
+    };
+}
+
+#[macro_export]
+macro_rules! panic {
+    ($msg:literal) => {
+        $crate::panic(&$msg)
+    };
+}
+
+#[rustc_intrinsic]
+#[rustc_intrinsic_const_stable_indirect]
+#[rustc_intrinsic_must_be_overridden]
+pub const fn size_of<T>() -> usize {
+    loop {}
+}
+
+#[rustc_intrinsic]
+#[rustc_intrinsic_must_be_overridden]
+pub const fn abort() -> ! {
+    loop {}
+}
+
+#[lang = "panic"]
+#[rustc_const_panic_str]
+const fn panic(_expr: &&'static str) -> ! {
+    abort();
+}
+
+#[lang = "eq"]
+pub trait PartialEq<Rhs: ?Sized = Self> {
+    fn eq(&self, other: &Rhs) -> bool;
+    fn ne(&self, other: &Rhs) -> bool {
+        !self.eq(other)
+    }
+}
+
+impl PartialEq for usize {
+    fn eq(&self, other: &usize) -> bool {
+        (*self) == (*other)
+    }
+}
+
+impl PartialEq for bool {
+    fn eq(&self, other: &bool) -> bool {
+        (*self) == (*other)
+    }
+}
+
+#[lang = "bitxor"]
+pub trait BitXor<Rhs = Self> {
+    type Output;
+    fn bitxor(self, rhs: Rhs) -> Self::Output;
+}
+
+impl BitXor for bool {
+    type Output = bool;
+    fn bitxor(self, rhs: bool) -> bool {
+        (self || rhs) && !(self && rhs)
+    }
+}
+
+#[lang = "not"]
+pub trait Not {
+    type Output;
+    fn not(self) -> Self::Output;
+}
+
+impl Not for bool {
+    type Output = bool;
+    fn not(self) -> Self {
+        !self
+    }
+}
diff --git a/tests/run-make/core-ffi-typecheck/rmake.rs b/tests/run-make/core-ffi-typecheck/rmake.rs
new file mode 100644
index 0000000000000..0856b5b4d362e
--- /dev/null
+++ b/tests/run-make/core-ffi-typecheck/rmake.rs
@@ -0,0 +1,163 @@
+use run_make_support::{clang, regex, rfs, rustc};
+
+const SKIPPED_TARGETS: &[&str] = &[
+    "riscv",  //error: unknown target triple 'riscv32e-unknown-none-elf'
+    "wasm",   //error: unknown target triple 'wasm32v1-none'
+    "xtensa", //error: unknown target triple 'xtensa-esp32-espidf'
+];
+
+fn main() {
+    let targets = get_target_list();
+
+    let minicore_path = run_make_support::source_root().join("tests/auxiliary/minicore.rs");
+
+    regex_mod();
+
+    for target in targets.lines() {
+        if SKIPPED_TARGETS.iter().any(|prefix| target.starts_with(prefix)) {
+            continue;
+        }
+
+        let clang_output =
+            clang().args(&["-E", "-dM", "-x", "c", "/dev/null", "-target", target]).run();
+
+        let defines = String::from_utf8(clang_output.stdout()).expect("Invalid UTF-8");
+
+        let minicore_content = rfs::read_to_string(&minicore_path);
+        let mut rmake_content = format!(
+            r#"
+            #![no_std]
+            #![no_core]
+            #![feature(intrinsics)]
+            #![feature(link_cfg)]
+            #![allow(unused)]
+            #![crate_type = "rlib"]
+            {}
+            #[path = "processed_mod.rs"]
+            mod ffi;
+            #[path = "tests.rs"]
+            mod tests;
+            "#,
+            minicore_content
+        );
+
+        rmake_content.push_str(&format!(
+            "
+            const CLANG_C_CHAR_SIZE: usize = {};
+            const CLANG_C_CHAR_SIGNED: bool = {};
+            const CLANG_C_SHORT_SIZE: usize = {};
+            const CLANG_C_INT_SIZE: usize = {};
+            const CLANG_C_LONG_SIZE: usize = {};
+            const CLANG_C_LONGLONG_SIZE: usize = {};
+            const CLANG_C_FLOAT_SIZE: usize = {};
+            const CLANG_C_DOUBLE_SIZE: usize = {};
+            ",
+            parse_size(&defines, "CHAR"),
+            parse_signed(&defines, "CHAR"),
+            parse_size(&defines, "SHORT"),
+            parse_size(&defines, "INT"),
+            parse_size(&defines, "LONG"),
+            parse_size(&defines, "LONG_LONG"),
+            parse_size(&defines, "FLOAT"),
+            parse_size(&defines, "DOUBLE"),
+        ));
+
+        // Write to target-specific rmake file
+        let mut file_name = format!("{}_rmake.rs", target.replace("-", "_"));
+
+        if target.starts_with("thumbv8m") {
+            file_name = String::from("thumbv8m_rmake.rs");
+        }
+
+        rfs::create_file(&file_name);
+        rfs::write(&file_name, rmake_content);
+        let rustc_output = rustc()
+            .arg("-Zunstable-options")
+            .arg("--emit=metadata")
+            .arg("--target")
+            .arg(target)
+            .arg(&file_name)
+            .run();
+        rfs::remove_file(&file_name);
+        if !rustc_output.status().success() {
+            panic!("Failed for target {}", target);
+        }
+    }
+
+    // Cleanup
+    rfs::remove_file("processed_mod.rs");
+}
+
+fn get_target_list() -> String {
+    let completed_process = rustc().arg("--print").arg("target-list").run();
+    String::from_utf8(completed_process.stdout()).expect("error not a string")
+}
+
+// Helper to parse size from clang defines
+fn parse_size(defines: &str, type_name: &str) -> usize {
+    let search_pattern = format!("__SIZEOF_{}__ ", type_name.to_uppercase());
+    for line in defines.lines() {
+        if line.contains(&search_pattern) {
+            if let Some(size_str) = line.split_whitespace().last() {
+                return size_str.parse().unwrap_or(0);
+            }
+        }
+    }
+
+    // Only allow CHAR to default to 1
+    if type_name.to_uppercase() == "CHAR" {
+        return 1;
+    }
+
+    panic!("Could not find size definition for type: {}", type_name);
+}
+
+// Helper to parse signedness from clang defines
+fn parse_signed(defines: &str, type_name: &str) -> bool {
+    match type_name.to_uppercase().as_str() {
+        "CHAR" => {
+            // Check if char is explicitly unsigned
+            !defines.lines().any(|line| line.contains("__CHAR_UNSIGNED__"))
+        }
+        _ => true,
+    }
+}
+
+// Parse core/ffi/mod.rs to retrieve only necessary macros and type defines
+fn regex_mod() {
+    let mod_path = run_make_support::source_root().join("library/core/src/ffi/mod.rs");
+    let mut content = rfs::read_to_string(&mod_path);
+
+    //remove stability features #![unstable]
+    let mut re = regex::Regex::new(r"#!?\[(un)?stable[^]]*?\]").unwrap();
+    content = re.replace_all(&content, "").to_string();
+
+    //remove doc features #[doc...]
+    re = regex::Regex::new(r"#\[doc[^]]*?\]").unwrap();
+    content = re.replace_all(&content, "").to_string();
+
+    //remove lang feature #[lang...]
+    re = regex::Regex::new(r"#\[lang[^]]*?\]").unwrap();
+    content = re.replace_all(&content, "").to_string();
+
+    //remove non inline modules
+    re = regex::Regex::new(r".*mod.*;").unwrap();
+    content = re.replace_all(&content, "").to_string();
+
+    //remove use
+    re = regex::Regex::new(r".*use.*;").unwrap();
+    content = re.replace_all(&content, "").to_string();
+
+    //remove fn fmt {...}
+    re = regex::Regex::new(r"(?s)fn fmt.*?\{.*?\}").unwrap();
+    content = re.replace_all(&content, "").to_string();
+
+    //rmv impl fmt {...}
+    re = regex::Regex::new(r"(?s)impl fmt::Debug for.*?\{.*?\}").unwrap();
+    content = re.replace_all(&content, "").to_string();
+
+    let file_name = format!("processed_mod.rs");
+
+    rfs::create_file(&file_name);
+    rfs::write(&file_name, content);
+}
diff --git a/tests/run-make/core-ffi-typecheck/tests.rs b/tests/run-make/core-ffi-typecheck/tests.rs
new file mode 100644
index 0000000000000..6946db2fe586f
--- /dev/null
+++ b/tests/run-make/core-ffi-typecheck/tests.rs
@@ -0,0 +1,147 @@
+// tests.rs
+
+use super::*; // `super` will include everything from `smallcore` once glued together
+
+cfg_if! {
+    if #[cfg(all(target_os = "windows", target_arch = "aarch64"))] {
+        const XFAIL_C_LONG_SIZE: usize = 4;
+        pub const TEST_C_LONG_SIZE: () = if size_of::<ffi::c_long>() != XFAIL_C_LONG_SIZE {
+            panic!("wrong c_long size test windows aarch64");
+        };
+    }
+    else if #[cfg(all(target_arch = "aarch64", target_abi = "ilp32"))] {
+        const XFAIL_C_LONG_SIZE: usize = 4;
+        pub const TEST_C_LONG_SIZE: () = if size_of::<ffi::c_long>() != XFAIL_C_LONG_SIZE {
+            panic!("wrong c_long size test ilp32");
+        };
+    }
+    else if #[cfg(all(target_pointer_width = "32", target_os = "watchos"))] {
+        const XFAIL_C_LONG_SIZE: usize = 4;
+        pub const TEST_C_LONG_SIZE: () = if size_of::<ffi::c_long>() != XFAIL_C_LONG_SIZE {
+            panic!("wrong c_long size test watchos");
+        };
+    }
+    else if #[cfg(any(
+        target_arch = "arm",
+        target_arch = "csky",
+        target_arch = "hexagon",
+        target_arch = "x86",
+        target_arch = "m68k",
+        target_arch = "mips",
+        target_arch = "mips32r6",
+        target_arch = "powerpc",
+        target_arch = "sparc"
+    ))] {
+        const XFAIL_C_LONG_SIZE: usize = 4;
+        pub const TEST_C_LONG_SIZE: () = if size_of::<ffi::c_long>() != XFAIL_C_LONG_SIZE {
+            panic!("wrong c_long size test for 32-bit architecture");
+        };
+    }
+    else if #[cfg(any(
+        target_arch = "avr",
+        target_arch = "msp430"
+    ))] {
+        const XFAIL_C_LONG_SIZE: usize = 4;
+        pub const TEST_C_LONG_SIZE: () = if size_of::<ffi::c_long>() != XFAIL_C_LONG_SIZE {
+            panic!("wrong c_long size test for embedded architecture");
+        };
+    }
+    else if #[cfg(all(target_arch = "x86_64", target_abi="x32"))] {
+        const XFAIL_C_LONG_SIZE: usize = 4;
+        pub const TEST_C_LONG_SIZE: () = if size_of::<ffi::c_long>() != XFAIL_C_LONG_SIZE {
+            panic!("wrong c_long size test x86_64 x32 ABI");
+        };
+    }
+    else {
+        // Default test
+        pub const TEST_C_LONG_SIZE: () = if size_of::<ffi::c_long>() != CLANG_C_LONG_SIZE {
+            panic!("wrong c_long size");
+        };
+    }
+}
+
+cfg_if! {
+    if #[cfg(target_arch = "csky")] {
+        const XFAIL_C_CHAR_SIGNED: bool = false;  // Change to true for darwin
+        pub const TEST_C_CHAR_UNSIGNED: () = if ffi::c_char::SIGNED ^ XFAIL_C_CHAR_SIGNED {
+            panic!("mismatched c_char signed, target_arch: csky");
+        };
+    }
+    else if #[cfg(target_arch = "msp430")] {
+        const XFAIL_C_CHAR_SIGNED: bool = false;  // Change to true for darwin
+        pub const TEST_C_CHAR_UNSIGNED: () = if ffi::c_char::SIGNED ^ XFAIL_C_CHAR_SIGNED {
+            panic!("mismatched c_char signed, target_arch: msp430");
+        };
+    }
+    else {
+        pub const TEST_C_CHAR_UNSIGNED: () = if ffi::c_char::SIGNED ^ CLANG_C_CHAR_SIGNED {
+            panic!("mismatched c_char sign");
+        };
+    }
+}
+
+cfg_if! {
+    if #[cfg(target_arch = "avr")] {
+        const XFAIL_C_INT_SIZE: usize = 2;
+         pub const TEST_C_INT_SIZE: () = if size_of::<ffi::c_int>() != XFAIL_C_INT_SIZE {
+            panic!("mismatched c_int size, target_arch: avr");
+        };
+    }
+    else if #[cfg(target_arch = "msp430")] {
+        const XFAIL_C_INT_SIZE: usize = 2;  // Change to true for darwin
+         pub const TEST_C_INT_SIZE: () = if size_of::<ffi::c_int>() != XFAIL_C_INT_SIZE {
+            panic!("mismatched c_int size, target_arch: msp430");
+        };
+    }
+    else {
+        pub const TEST_C_INT_SIZE: () = if size_of::<ffi::c_int>() != CLANG_C_INT_SIZE {
+            panic!("wrong c_int size");
+        };
+    }
+}
+
+cfg_if! {
+    if #[cfg(target_arch = "avr")] {
+        const XFAIL_C_DOUBLE_SIZE: usize = 4;
+         pub const TEST_C_DOUBLE_SIZE: () = if size_of::<ffi::c_double>() != XFAIL_C_DOUBLE_SIZE {
+            panic!("wrong c_double size, target_arch: avr");
+        };
+    }
+    else {
+        pub const TEST_C_DOUBLE_SIZE: () = if size_of::<ffi::c_double>() != CLANG_C_DOUBLE_SIZE {
+            panic!("wrong c_double size");
+        };
+    }
+}
+
+trait Signed {
+    const SIGNED: bool;
+}
+
+impl Signed for i8 {
+    const SIGNED: bool = true;
+}
+
+impl Signed for u8 {
+    const SIGNED: bool = false;
+}
+
+//c_char size
+pub const TEST_C_CHAR_SIZE: () = if size_of::<ffi::c_char>() != CLANG_C_CHAR_SIZE {
+    panic!("wrong c_char size");
+};
+
+//c_short size
+pub const TEST_C_SHORT_SIZE: () = if size_of::<ffi::c_short>() != CLANG_C_SHORT_SIZE {
+    panic!("wrong c_short size");
+};
+
+//c_longlong size
+pub const TEST_C_LONGLONG_SIZE: () = if size_of::<ffi::c_longlong>() != CLANG_C_LONGLONG_SIZE {
+    panic!("wrong c_longlong size");
+};
+
+//c_float size
+pub const TEST_C_FLOAT_SIZE: () = if size_of::<ffi::c_float>() != CLANG_C_FLOAT_SIZE {
+    panic!("wrong c_float size");
+};