Check ty is sized in build_malloc (fixes rust-lang#150)

Author: willtunnels

src/builder.rs

@@ -12,7 +12,7 @@ use crate::basic_block::BasicBlock;
 use crate::values::{AggregateValue, AggregateValueEnum, AsValueRef, BasicValue, BasicValueEnum, PhiValue, FunctionValue, IntValue, PointerValue, VectorValue, InstructionValue, GlobalValue, IntMathValue, FloatMathValue, PointerMathValue, InstructionOpcode, CallSiteValue};
 #[llvm_versions(3.9..=latest)]
 use crate::values::StructValue;
-use crate::types::{AsTypeRef, BasicType, IntMathType, FloatMathType, PointerType, PointerMathType};
+use crate::types::{AsTypeRef, BasicType, BasicTypeEnum, IntMathType, FloatMathType, PointerType, PointerMathType};
 
 use std::ffi::CString;
 use std::marker::PhantomData;
@@ -349,6 +349,19 @@ impl<'ctx> Builder<'ctx> {
 
     // TODOC: Heap allocation
     pub fn build_malloc<T: BasicType<'ctx>>(&self, ty: T, name: &str) -> PointerValue<'ctx> {
+        // LLVMBulidMalloc segfaults if ty is unsized
+        let is_sized = match ty.as_basic_type_enum() {
+            BasicTypeEnum::ArrayType(ty) => ty.is_sized(),
+            BasicTypeEnum::FloatType(ty) => ty.is_sized(),
+            BasicTypeEnum::IntType(ty) => ty.is_sized(),
+            BasicTypeEnum::PointerType(ty) => ty.is_sized(),
+            BasicTypeEnum::StructType(ty) => ty.is_sized(),
+            BasicTypeEnum::VectorType(ty) => ty.is_sized(),
+        };
+        if !is_sized {
+            panic!("Cannot build malloc call for an unsized type {:?}", ty);
+        }
+
         let c_string = CString::new(name).expect("Conversion to CString failed unexpectedly");
 
         let value = unsafe {