Add regression test

Author: maxdexh

flake.nix

@@ -0,0 +1,63 @@
+{
+  description = "A flake for rust development";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = {
+    self,
+    nixpkgs,
+    flake-utils,
+  }:
+    flake-utils.lib.eachDefaultSystem (
+      system: let
+        pkgs = nixpkgs.legacyPackages.${system};
+        libs = with pkgs.stdenv.cc; {
+          ccLib = cc.lib;
+          libc = libc;
+          libcDev = libc.dev;
+          libcStatic = libc.static;
+          libgcc = cc.libgcc;
+        };
+      in
+        with pkgs; {
+          devShells.default = mkShell {
+            name = "rust-dev-gcc";
+
+            # Make clang aware of a few headers
+            BINDGEN_EXTRA_CLANG_ARGS = ''-isystem ${libs.libcDev}/include'';
+
+            # libc dynamic libraries
+            LD_LIBRARY_PATH = lib.makeLibraryPath [
+              libs.ccLib
+              libs.libc
+              libs.libgcc
+              zlib
+            ];
+
+            # libc static libraries
+            LIBRARY_PATH = lib.makeLibraryPath [libs.libcStatic];
+
+            nativeBuildInputs = [
+              cmake
+              curl
+              python3
+              pkg-config
+            ];
+
+            shellHook = ''
+              alias x_wrapped="setarch $(uname -m) $(pwd)/x"
+              no_randomize=$(setarch --show | grep "ADDR_NO_RANDOMIZE")
+              if [ -n no_randomize ];
+              then
+                echo 'The ADDR_NO_RANDOMIZE flag is set.'
+                echo "Use the \"setarch\" program to unset this flag: \"setarch $(uname -m) ./x ...\"."
+                echo "Alternatively, you can use the following alias: \"x_wrapped\"."
+              fi;
+            '';
+          };
+        }
+    );
+}

tests/ui/coercion/intrinsic-in-unifying-coercion-149143.rs

@@ -0,0 +1,19 @@
+// Regression test for #149143.
+// The compiler did not check for a coercion from intrinsics
+// to fn ptrs in all possible code paths that could lead to such a coercion.
+// This caused an ICE during a later sanity check.
+
+use std::mem::transmute;
+
+fn main() {
+    unsafe {
+        let f = if true { transmute } else { safe_transmute };
+        //~^ ERROR `if` and `else` have incompatible type
+
+        let _: i64 = f(5i64);
+    }
+}
+
+unsafe fn safe_transmute<A, B>(x: A) -> B {
+    panic!()
+}

tests/ui/coercion/intrinsic-in-unifying-coercion-149143.stderr

@@ -0,0 +1,15 @@
+error[E0308]: `if` and `else` have incompatible types
+  --> $DIR/intrinsic-in-unifying-coercion-149143.rs:10:46
+   |
+LL |         let f = if true { transmute } else { safe_transmute };
+   |                           ---------          ^^^^^^^^^^^^^^ cannot coerce intrinsics to function pointers
+   |                           |
+   |                           expected because of this
+   |
+   = note: expected fn item `unsafe fn(_) -> _ {std::intrinsics::transmute::<_, _>}`
+              found fn item `unsafe fn(_) -> _ {safe_transmute::<_, _>}`
+   = note: different fn items have unique types, even if their signatures are the same
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.