Roll-forward "Allow bundled debug build (Rust-SDL2#1081)"

Roll this forward again to make merge easier.

changelog.md

@@ -3,7 +3,7 @@ when upgrading from a version of rust-sdl2 to another.
 
 ### Unreleased
 
-* Rollback PR #1081: Broke dynamic linking on Windows #1088
+Nothing for now
 
 ### v0.34.4
 

sdl2-sys/build.rs

@@ -293,7 +293,6 @@ fn patch_sdl2(sdl2_source_path: &Path) {
 #[cfg(feature = "bundled")]
 fn compile_sdl2(sdl2_build_path: &Path, target_os: &str) -> PathBuf {
     let mut cfg = cmake::Config::new(sdl2_build_path);
-    cfg.profile("release");
 
     // Override __FLTUSED__ to keep the _fltused symbol from getting defined in the static build.
     // This conflicts and fails to link properly when building statically on Windows, likely due to
@@ -411,11 +410,24 @@ fn link_sdl2(target_os: &str) {
 
     #[cfg(feature = "static-link")]
     {
+        // There's no way to extract this from `cmake::Config` so we have to emulate their
+        // behaviour here (see the source for `cmake::Config::build`).
+        let debug_postfix = match (
+            &env::var("OPT_LEVEL").unwrap_or_default()[..],
+            &env::var("PROFILE").unwrap_or_default()[..],
+        ) {
+            ("1", _) | ("2", _) | ("3", _) | ("s", _) | ("z", _) => "",
+            ("0", _) => "d",
+            (_, "debug") => "d",
+            // ("0", _) => "",
+            // (_, "debug") => "",
+            (_, _) => "",
+        };
         if cfg!(feature = "bundled")
             || (cfg!(feature = "use-pkgconfig") == false && cfg!(feature = "use-vcpkg") == false)
         {
-            println!("cargo:rustc-link-lib=static=SDL2main");
-            println!("cargo:rustc-link-lib=static=SDL2");
+            println!("cargo:rustc-link-lib=static=SDL2main{}", debug_postfix);
+            println!("cargo:rustc-link-lib=static=SDL2{}", debug_postfix);
         }
 
         // Also linked to any required libraries for each supported platform