[rfc] Use a dynamically loaded clang to do as much as we can with old clang versions, and experiment with new ones.

bindgen/Cargo.toml

@@ -15,7 +15,7 @@ version = "0.17.0"
 workspace = ".."
 
 [dependencies]
-clang-sys = "0.11.1"
+clang-sys = "0.12"
 clap = "2"
 libbindgen = { path = "../libbindgen" }
 log = "0.3"

libbindgen/Cargo.toml

@@ -26,7 +26,7 @@ quasi_codegen = "0.26"
 [dependencies]
 cexpr = "0.2"
 cfg-if = "0.1.0"
-clang-sys = { version = "0.11.1", features = ["gte_clang_3_6", "gte_clang_3_7", "gte_clang_3_8", "gte_clang_3_9"] }
+clang-sys = { version = "0.12", features = ["runtime", "clang_3_9"] }
 lazy_static = "0.2.1"
 libc = "0.2"
 rustc-serialize = "0.3.19"

libbindgen/src/clang.rs

@@ -349,19 +349,9 @@ impl Cursor {
     }
 
     /// Is the referent an inlined function?
-    #[cfg(not(feature="llvm_stable"))]
     pub fn is_inlined_function(&self) -> bool {
-        unsafe { clang_Cursor_isFunctionInlined(self.x) != 0 }
-    }
-
-    // TODO: Remove this when LLVM 3.9 is released.
-    //
-    // This is currently used for CI purposes.
-
-    /// Is the referent an inlined function?
-    #[cfg(feature="llvm_stable")]
-    pub fn is_inlined_function(&self) -> bool {
-        false
+        clang_Cursor_isFunctionInlined::is_loaded() &&
+            unsafe { clang_Cursor_isFunctionInlined(self.x) != 0 }
     }
 
     /// Get the width of this cursor's referent bit field, or `None` if the
@@ -762,7 +752,6 @@ impl Type {
 
     /// For elaborated types (types which use `class`, `struct`, or `union` to
     /// disambiguate types from local bindings), get the underlying type.
-    #[cfg(not(feature="llvm_stable"))]
     pub fn named(&self) -> Type {
         unsafe {
             Type {
@@ -1306,28 +1295,13 @@ pub struct EvalResult {
     x: CXEvalResult,
 }
 
-#[cfg(feature = "llvm_stable")]
-impl EvalResult {
-    /// Create a dummy EvalResult.
-    pub fn new(_: Cursor) -> Option<Self> {
-        None
-    }
-
-    /// Not useful in llvm 3.8.
-    pub fn as_double(&self) -> Option<f64> {
-        None
-    }
-
-    /// Not useful in llvm 3.8.
-    pub fn as_int(&self) -> Option<i32> {
-        None
-    }
-}
-
-#[cfg(not(feature = "llvm_stable"))]
 impl EvalResult {
     /// Evaluate `cursor` and return the result.
     pub fn new(cursor: Cursor) -> Option<Self> {
+        if !clang_Cursor_Evaluate::is_loaded() {
+            return None;
+        }
+
         // Clang has an internal assertion we can trigger if we try to evaluate
         // a cursor containing a variadic template type reference. Triggering
         // the assertion aborts the process, and we don't want that. Clang
@@ -1379,7 +1353,6 @@ impl EvalResult {
     }
 }
 
-#[cfg(not(feature = "llvm_stable"))]
 impl Drop for EvalResult {
     fn drop(&mut self) {
         unsafe { clang_EvalResult_dispose(self.x) };

libbindgen/src/ir/ty.rs

@@ -854,7 +854,6 @@ impl Type {
                     .expect("Not able to resolve array element?");
                 TypeKind::Array(inner, ty.num_elements().unwrap())
             }
-            #[cfg(not(feature="llvm_stable"))]
             CXType_Elaborated => {
                 return Self::from_clang_ty(potential_id,
                                            &ty.named(),

libbindgen/src/lib.rs

@@ -511,6 +511,10 @@ impl<'ctx> Bindings<'ctx> {
                     span: Option<Span>)
                     -> Result<Bindings<'ctx>, ()> {
         let span = span.unwrap_or(DUMMY_SP);
+        if !clang_sys::is_loaded() {
+            // TODO(emilio): Return meaningful error (breaking).
+            clang_sys::load().expect("Unable to find libclang");
+        }
 
         // TODO: Make this path fixup configurable?
         if let Some(clang) = clang_sys::support::Clang::find(None) {
@@ -691,6 +695,11 @@ pub struct ClangVersion {
 
 /// Get the major and the minor semvar numbers of Clang's version
 pub fn clang_version() -> ClangVersion {
+    if !clang_sys::is_loaded() {
+        // TODO(emilio): Return meaningful error (breaking).
+        clang_sys::load().expect("Unable to find libclang");
+    }
+
     let raw_v: String = clang::extract_clang_version();
     let split_v: Option<Vec<&str>> = raw_v.split_whitespace()
         .nth(2)