diff --git a/cranelift/wasm/src/code_translator.rs b/cranelift/wasm/src/code_translator.rs
index 43d08c6713..05c5de4f55 100644
--- a/cranelift/wasm/src/code_translator.rs
+++ b/cranelift/wasm/src/code_translator.rs
@@ -23,12 +23,13 @@
 //! That is why `translate_function_body` takes an object having the `WasmRuntime` trait as
 //! argument.
 use super::{hash_map, HashMap};
-use crate::environ::{FuncEnvironment, GlobalVariable, ReturnMode, WasmError, WasmResult};
+use crate::environ::{FuncEnvironment, GlobalVariable, ReturnMode, WasmResult};
 use crate::state::{ControlStackFrame, TranslationState};
 use crate::translation_utils::{
     blocktype_to_type, f32_translation, f64_translation, num_return_values,
 };
 use crate::translation_utils::{FuncIndex, MemoryIndex, SignatureIndex, TableIndex};
+use crate::wasm_unsupported;
 use core::{i32, u32};
 use cranelift_codegen::ir::condcodes::{FloatCC, IntCC};
 use cranelift_codegen::ir::types::*;
@@ -899,10 +900,10 @@ pub fn translate_operator<FE: FuncEnvironment + ?Sized>(
         | Operator::I64AtomicRmw8UCmpxchg { .. }
         | Operator::I64AtomicRmw16UCmpxchg { .. }
         | Operator::I64AtomicRmw32UCmpxchg { .. } => {
-            return Err(WasmError::Unsupported("proposed thread operators"));
+            wasm_unsupported!("proposed thread operator {:?}", op);
         }
         Operator::RefNull | Operator::RefIsNull { .. } => {
-            return Err(WasmError::Unsupported("proposed reference-type operators"));
+            wasm_unsupported!("proposed reference-type operator {:?}", op);
         }
         Operator::MemoryInit { .. }
         | Operator::DataDrop { .. }
@@ -915,7 +916,7 @@ pub fn translate_operator<FE: FuncEnvironment + ?Sized>(
         | Operator::TableSet { .. }
         | Operator::TableGrow { .. }
         | Operator::TableSize { .. } => {
-            return Err(WasmError::Unsupported("proposed bulk memory operators"));
+            wasm_unsupported!("proposed bulk memory operator {:?}", op);
         }
         Operator::V128Load { .. }
         | Operator::V128Store { .. }
@@ -1059,7 +1060,7 @@ pub fn translate_operator<FE: FuncEnvironment + ?Sized>(
         | Operator::F64x2ConvertUI64x2
         | Operator::V8x16Shuffle1
         | Operator::V8x16Shuffle2Imm { .. } => {
-            return Err(WasmError::Unsupported("proposed SIMD operators"));
+            wasm_unsupported!("proposed SIMD operator {:?}", op);
         }
     };
     Ok(())
diff --git a/cranelift/wasm/src/environ/dummy.rs b/cranelift/wasm/src/environ/dummy.rs
index 0404ccb522..fcec4e648c 100644
--- a/cranelift/wasm/src/environ/dummy.rs
+++ b/cranelift/wasm/src/environ/dummy.rs
@@ -367,8 +367,9 @@ impl<'data> ModuleEnvironment<'data> for DummyEnvironment {
         self.info.config
     }
 
-    fn declare_signature(&mut self, sig: ir::Signature) {
+    fn declare_signature(&mut self, sig: ir::Signature) -> WasmResult<()> {
         self.info.signatures.push(sig);
+        Ok(())
     }
 
     fn declare_func_import(
@@ -376,7 +377,7 @@ impl<'data> ModuleEnvironment<'data> for DummyEnvironment {
         sig_index: SignatureIndex,
         module: &'data str,
         field: &'data str,
-    ) {
+    ) -> WasmResult<()> {
         assert_eq!(
             self.info.functions.len(),
             self.info.imported_funcs.len(),
@@ -386,32 +387,48 @@ impl<'data> ModuleEnvironment<'data> for DummyEnvironment {
         self.info
             .imported_funcs
             .push((String::from(module), String::from(field)));
+        Ok(())
     }
 
-    fn declare_func_type(&mut self, sig_index: SignatureIndex) {
+    fn declare_func_type(&mut self, sig_index: SignatureIndex) -> WasmResult<()> {
         self.info.functions.push(Exportable::new(sig_index));
+        Ok(())
     }
 
-    fn declare_global(&mut self, global: Global) {
+    fn declare_global(&mut self, global: Global) -> WasmResult<()> {
         self.info.globals.push(Exportable::new(global));
+        Ok(())
     }
 
-    fn declare_global_import(&mut self, global: Global, module: &'data str, field: &'data str) {
+    fn declare_global_import(
+        &mut self,
+        global: Global,
+        module: &'data str,
+        field: &'data str,
+    ) -> WasmResult<()> {
         self.info.globals.push(Exportable::new(global));
         self.info
             .imported_globals
             .push((String::from(module), String::from(field)));
+        Ok(())
     }
 
-    fn declare_table(&mut self, table: Table) {
+    fn declare_table(&mut self, table: Table) -> WasmResult<()> {
         self.info.tables.push(Exportable::new(table));
+        Ok(())
     }
 
-    fn declare_table_import(&mut self, table: Table, module: &'data str, field: &'data str) {
+    fn declare_table_import(
+        &mut self,
+        table: Table,
+        module: &'data str,
+        field: &'data str,
+    ) -> WasmResult<()> {
         self.info.tables.push(Exportable::new(table));
         self.info
             .imported_tables
             .push((String::from(module), String::from(field)));
+        Ok(())
     }
 
     fn declare_table_elements(
@@ -420,19 +437,27 @@ impl<'data> ModuleEnvironment<'data> for DummyEnvironment {
         _base: Option<GlobalIndex>,
         _offset: usize,
         _elements: Box<[FuncIndex]>,
-    ) {
+    ) -> WasmResult<()> {
         // We do nothing
+        Ok(())
     }
 
-    fn declare_memory(&mut self, memory: Memory) {
+    fn declare_memory(&mut self, memory: Memory) -> WasmResult<()> {
         self.info.memories.push(Exportable::new(memory));
+        Ok(())
     }
 
-    fn declare_memory_import(&mut self, memory: Memory, module: &'data str, field: &'data str) {
+    fn declare_memory_import(
+        &mut self,
+        memory: Memory,
+        module: &'data str,
+        field: &'data str,
+    ) -> WasmResult<()> {
         self.info.memories.push(Exportable::new(memory));
         self.info
             .imported_memories
             .push((String::from(module), String::from(field)));
+        Ok(())
     }
 
     fn declare_data_initialization(
@@ -441,37 +466,55 @@ impl<'data> ModuleEnvironment<'data> for DummyEnvironment {
         _base: Option<GlobalIndex>,
         _offset: usize,
         _data: &'data [u8],
-    ) {
+    ) -> WasmResult<()> {
         // We do nothing
+        Ok(())
     }
 
-    fn declare_func_export(&mut self, func_index: FuncIndex, name: &'data str) {
+    fn declare_func_export(&mut self, func_index: FuncIndex, name: &'data str) -> WasmResult<()> {
         self.info.functions[func_index]
             .export_names
             .push(String::from(name));
+        Ok(())
     }
 
-    fn declare_table_export(&mut self, table_index: TableIndex, name: &'data str) {
+    fn declare_table_export(
+        &mut self,
+        table_index: TableIndex,
+        name: &'data str,
+    ) -> WasmResult<()> {
         self.info.tables[table_index]
             .export_names
             .push(String::from(name));
+        Ok(())
     }
 
-    fn declare_memory_export(&mut self, memory_index: MemoryIndex, name: &'data str) {
+    fn declare_memory_export(
+        &mut self,
+        memory_index: MemoryIndex,
+        name: &'data str,
+    ) -> WasmResult<()> {
         self.info.memories[memory_index]
             .export_names
             .push(String::from(name));
+        Ok(())
     }
 
-    fn declare_global_export(&mut self, global_index: GlobalIndex, name: &'data str) {
+    fn declare_global_export(
+        &mut self,
+        global_index: GlobalIndex,
+        name: &'data str,
+    ) -> WasmResult<()> {
         self.info.globals[global_index]
             .export_names
             .push(String::from(name));
+        Ok(())
     }
 
-    fn declare_start_func(&mut self, func_index: FuncIndex) {
+    fn declare_start_func(&mut self, func_index: FuncIndex) -> WasmResult<()> {
         debug_assert!(self.info.start_func.is_none());
         self.info.start_func = Some(func_index);
+        Ok(())
     }
 
     fn define_function_body(
diff --git a/cranelift/wasm/src/environ/mod.rs b/cranelift/wasm/src/environ/mod.rs
index 831fa0ef5e..4b7405ea7b 100644
--- a/cranelift/wasm/src/environ/mod.rs
+++ b/cranelift/wasm/src/environ/mod.rs
@@ -1,6 +1,7 @@
 //! Support for configurable wasm translation.
 
 mod dummy;
+#[macro_use]
 mod spec;
 
 pub use crate::environ::dummy::DummyEnvironment;
diff --git a/cranelift/wasm/src/environ/spec.rs b/cranelift/wasm/src/environ/spec.rs
index c1aa9e8dd7..c94131fa9f 100644
--- a/cranelift/wasm/src/environ/spec.rs
+++ b/cranelift/wasm/src/environ/spec.rs
@@ -60,7 +60,7 @@ pub enum WasmError {
     ///
     /// Embedding environments may have their own limitations and feature restrictions.
     #[fail(display = "Unsupported feature: {}", _0)]
-    Unsupported(&'static str),
+    Unsupported(std::string::String),
 
     /// An implementation limit was exceeded.
     ///
@@ -76,6 +76,13 @@ pub enum WasmError {
     User(std::string::String),
 }
 
+/// Return an `Err(WasmError::Unsupported(msg))` where `msg` the string built by calling `format!`
+/// on the arguments to this macro.
+#[macro_export]
+macro_rules! wasm_unsupported {
+    ($($arg:tt)*) => { return Err($crate::environ::WasmError::Unsupported(format!($($arg)*))) }
+}
+
 impl From<BinaryReaderError> for WasmError {
     /// Convert from a `BinaryReaderError` to a `WasmError`.
     fn from(e: BinaryReaderError) -> Self {
@@ -289,14 +296,18 @@ pub trait ModuleEnvironment<'data> {
 
     /// Provides the number of signatures up front. By default this does nothing, but
     /// implementations can use this to preallocate memory if desired.
-    fn reserve_signatures(&mut self, _num: u32) {}
+    fn reserve_signatures(&mut self, _num: u32) -> WasmResult<()> {
+        Ok(())
+    }
 
     /// Declares a function signature to the environment.
-    fn declare_signature(&mut self, sig: ir::Signature);
+    fn declare_signature(&mut self, sig: ir::Signature) -> WasmResult<()>;
 
     /// Provides the number of imports up front. By default this does nothing, but
     /// implementations can use this to preallocate memory if desired.
-    fn reserve_imports(&mut self, _num: u32) {}
+    fn reserve_imports(&mut self, _num: u32) -> WasmResult<()> {
+        Ok(())
+    }
 
     /// Declares a function import to the environment.
     fn declare_func_import(
@@ -304,73 +315,113 @@ pub trait ModuleEnvironment<'data> {
         sig_index: SignatureIndex,
         module: &'data str,
         field: &'data str,
-    );
+    ) -> WasmResult<()>;
 
     /// Declares a table import to the environment.
-    fn declare_table_import(&mut self, table: Table, module: &'data str, field: &'data str);
+    fn declare_table_import(
+        &mut self,
+        table: Table,
+        module: &'data str,
+        field: &'data str,
+    ) -> WasmResult<()>;
 
     /// Declares a memory import to the environment.
-    fn declare_memory_import(&mut self, memory: Memory, module: &'data str, field: &'data str);
+    fn declare_memory_import(
+        &mut self,
+        memory: Memory,
+        module: &'data str,
+        field: &'data str,
+    ) -> WasmResult<()>;
 
     /// Declares a global import to the environment.
-    fn declare_global_import(&mut self, global: Global, module: &'data str, field: &'data str);
+    fn declare_global_import(
+        &mut self,
+        global: Global,
+        module: &'data str,
+        field: &'data str,
+    ) -> WasmResult<()>;
 
     /// Notifies the implementation that all imports have been declared.
-    fn finish_imports(&mut self) {}
+    fn finish_imports(&mut self) -> WasmResult<()> {
+        Ok(())
+    }
 
     /// Provides the number of defined functions up front. By default this does nothing, but
     /// implementations can use this to preallocate memory if desired.
-    fn reserve_func_types(&mut self, _num: u32) {}
+    fn reserve_func_types(&mut self, _num: u32) -> WasmResult<()> {
+        Ok(())
+    }
 
     /// Declares the type (signature) of a local function in the module.
-    fn declare_func_type(&mut self, sig_index: SignatureIndex);
+    fn declare_func_type(&mut self, sig_index: SignatureIndex) -> WasmResult<()>;
 
     /// Provides the number of defined tables up front. By default this does nothing, but
     /// implementations can use this to preallocate memory if desired.
-    fn reserve_tables(&mut self, _num: u32) {}
+    fn reserve_tables(&mut self, _num: u32) -> WasmResult<()> {
+        Ok(())
+    }
 
     /// Declares a table to the environment.
-    fn declare_table(&mut self, table: Table);
+    fn declare_table(&mut self, table: Table) -> WasmResult<()>;
 
     /// Provides the number of defined memories up front. By default this does nothing, but
     /// implementations can use this to preallocate memory if desired.
-    fn reserve_memories(&mut self, _num: u32) {}
+    fn reserve_memories(&mut self, _num: u32) -> WasmResult<()> {
+        Ok(())
+    }
 
     /// Declares a memory to the environment
-    fn declare_memory(&mut self, memory: Memory);
+    fn declare_memory(&mut self, memory: Memory) -> WasmResult<()>;
 
     /// Provides the number of defined globals up front. By default this does nothing, but
     /// implementations can use this to preallocate memory if desired.
-    fn reserve_globals(&mut self, _num: u32) {}
+    fn reserve_globals(&mut self, _num: u32) -> WasmResult<()> {
+        Ok(())
+    }
 
     /// Declares a global to the environment.
-    fn declare_global(&mut self, global: Global);
+    fn declare_global(&mut self, global: Global) -> WasmResult<()>;
 
     /// Provides the number of exports up front. By default this does nothing, but
     /// implementations can use this to preallocate memory if desired.
-    fn reserve_exports(&mut self, _num: u32) {}
+    fn reserve_exports(&mut self, _num: u32) -> WasmResult<()> {
+        Ok(())
+    }
 
     /// Declares a function export to the environment.
-    fn declare_func_export(&mut self, func_index: FuncIndex, name: &'data str);
+    fn declare_func_export(&mut self, func_index: FuncIndex, name: &'data str) -> WasmResult<()>;
 
     /// Declares a table export to the environment.
-    fn declare_table_export(&mut self, table_index: TableIndex, name: &'data str);
+    fn declare_table_export(&mut self, table_index: TableIndex, name: &'data str)
+        -> WasmResult<()>;
 
     /// Declares a memory export to the environment.
-    fn declare_memory_export(&mut self, memory_index: MemoryIndex, name: &'data str);
+    fn declare_memory_export(
+        &mut self,
+        memory_index: MemoryIndex,
+        name: &'data str,
+    ) -> WasmResult<()>;
 
     /// Declares a global export to the environment.
-    fn declare_global_export(&mut self, global_index: GlobalIndex, name: &'data str);
+    fn declare_global_export(
+        &mut self,
+        global_index: GlobalIndex,
+        name: &'data str,
+    ) -> WasmResult<()>;
 
     /// Notifies the implementation that all exports have been declared.
-    fn finish_exports(&mut self) {}
+    fn finish_exports(&mut self) -> WasmResult<()> {
+        Ok(())
+    }
 
     /// Declares the optional start function.
-    fn declare_start_func(&mut self, index: FuncIndex);
+    fn declare_start_func(&mut self, index: FuncIndex) -> WasmResult<()>;
 
     /// Provides the number of element initializers up front. By default this does nothing, but
     /// implementations can use this to preallocate memory if desired.
-    fn reserve_table_elements(&mut self, _num: u32) {}
+    fn reserve_table_elements(&mut self, _num: u32) -> WasmResult<()> {
+        Ok(())
+    }
 
     /// Fills a declared table with references to functions in the module.
     fn declare_table_elements(
@@ -379,7 +430,7 @@ pub trait ModuleEnvironment<'data> {
         base: Option<GlobalIndex>,
         offset: usize,
         elements: Box<[FuncIndex]>,
-    );
+    ) -> WasmResult<()>;
 
     /// Provides the contents of a function body.
     ///
@@ -393,7 +444,9 @@ pub trait ModuleEnvironment<'data> {
 
     /// Provides the number of data initializers up front. By default this does nothing, but
     /// implementations can use this to preallocate memory if desired.
-    fn reserve_data_initializers(&mut self, _num: u32) {}
+    fn reserve_data_initializers(&mut self, _num: u32) -> WasmResult<()> {
+        Ok(())
+    }
 
     /// Fills a declared memory with bytes at module instantiation.
     fn declare_data_initialization(
@@ -402,5 +455,5 @@ pub trait ModuleEnvironment<'data> {
         base: Option<GlobalIndex>,
         offset: usize,
         data: &'data [u8],
-    );
+    ) -> WasmResult<()>;
 }
diff --git a/cranelift/wasm/src/func_translator.rs b/cranelift/wasm/src/func_translator.rs
index a2ecdd06b3..7f62f5cfe0 100644
--- a/cranelift/wasm/src/func_translator.rs
+++ b/cranelift/wasm/src/func_translator.rs
@@ -5,9 +5,10 @@
 //! WebAssembly module and the runtime environment.
 
 use crate::code_translator::translate_operator;
-use crate::environ::{FuncEnvironment, ReturnMode, WasmError, WasmResult};
+use crate::environ::{FuncEnvironment, ReturnMode, WasmResult};
 use crate::state::{TranslationState, VisibleTranslationState};
 use crate::translation_utils::get_vmctx_value_label;
+use crate::wasm_unsupported;
 use cranelift_codegen::entity::EntityRef;
 use cranelift_codegen::ir::{self, Ebb, InstBuilder, ValueLabel};
 use cranelift_codegen::timing;
@@ -176,7 +177,7 @@ fn declare_locals(
         I64 => builder.ins().iconst(ir::types::I64, 0),
         F32 => builder.ins().f32const(ir::immediates::Ieee32::with_bits(0)),
         F64 => builder.ins().f64const(ir::immediates::Ieee64::with_bits(0)),
-        _ => return Err(WasmError::Unsupported("unsupported local type")),
+        ty => wasm_unsupported!("unsupported local type {:?}", ty),
     };
 
     let ty = builder.func.dfg.value_type(zeroval);
diff --git a/cranelift/wasm/src/sections_translator.rs b/cranelift/wasm/src/sections_translator.rs
index f0975d9643..4ca8a66b87 100644
--- a/cranelift/wasm/src/sections_translator.rs
+++ b/cranelift/wasm/src/sections_translator.rs
@@ -7,11 +7,12 @@
 //! The special case of the initialize expressions for table elements offsets or global variables
 //! is handled, according to the semantics of WebAssembly, to only specific expressions that are
 //! interpreted on the fly.
-use crate::environ::{ModuleEnvironment, WasmError, WasmResult};
+use crate::environ::{ModuleEnvironment, WasmResult};
 use crate::translation_utils::{
     tabletype_to_type, type_to_type, FuncIndex, Global, GlobalIndex, GlobalInit, Memory,
     MemoryIndex, SignatureIndex, Table, TableElementType, TableIndex,
 };
+use crate::wasm_unsupported;
 use core::convert::TryFrom;
 use cranelift_codegen::ir::{self, AbiParam, Signature};
 use cranelift_entity::EntityRef;
@@ -29,7 +30,7 @@ pub fn parse_type_section(
     types: TypeSectionReader,
     environ: &mut dyn ModuleEnvironment,
 ) -> WasmResult<()> {
-    environ.reserve_signatures(types.get_count());
+    environ.reserve_signatures(types.get_count())?;
 
     for entry in types {
         match entry? {
@@ -49,9 +50,9 @@ pub fn parse_type_section(
                         .expect("only numeric types are supported in function signatures");
                     AbiParam::new(cret_arg)
                 }));
-                environ.declare_signature(sig);
+                environ.declare_signature(sig)?;
             }
-            _ => return Err(WasmError::Unsupported("unsupported type in type section")),
+            ty => wasm_unsupported!("unsupported type in type section: {:?}", ty),
         }
     }
     Ok(())
@@ -62,7 +63,7 @@ pub fn parse_import_section<'data>(
     imports: ImportSectionReader<'data>,
     environ: &mut dyn ModuleEnvironment<'data>,
 ) -> WasmResult<()> {
-    environ.reserve_imports(imports.get_count());
+    environ.reserve_imports(imports.get_count())?;
 
     for entry in imports {
         let import = entry?;
@@ -71,7 +72,11 @@ pub fn parse_import_section<'data>(
 
         match import.ty {
             ImportSectionEntryType::Function(sig) => {
-                environ.declare_func_import(SignatureIndex::from_u32(sig), module_name, field_name);
+                environ.declare_func_import(
+                    SignatureIndex::from_u32(sig),
+                    module_name,
+                    field_name,
+                )?;
             }
             ImportSectionEntryType::Memory(MemoryType {
                 limits: ref memlimits,
@@ -85,7 +90,7 @@ pub fn parse_import_section<'data>(
                     },
                     module_name,
                     field_name,
-                );
+                )?;
             }
             ImportSectionEntryType::Global(ref ty) => {
                 environ.declare_global_import(
@@ -96,7 +101,7 @@ pub fn parse_import_section<'data>(
                     },
                     module_name,
                     field_name,
-                );
+                )?;
             }
             ImportSectionEntryType::Table(ref tab) => {
                 environ.declare_table_import(
@@ -110,12 +115,12 @@ pub fn parse_import_section<'data>(
                     },
                     module_name,
                     field_name,
-                );
+                )?;
             }
         }
     }
 
-    environ.finish_imports();
+    environ.finish_imports()?;
     Ok(())
 }
 
@@ -124,11 +129,11 @@ pub fn parse_function_section(
     functions: FunctionSectionReader,
     environ: &mut dyn ModuleEnvironment,
 ) -> WasmResult<()> {
-    environ.reserve_func_types(functions.get_count());
+    environ.reserve_func_types(functions.get_count())?;
 
     for entry in functions {
         let sigindex = entry?;
-        environ.declare_func_type(SignatureIndex::from_u32(sigindex));
+        environ.declare_func_type(SignatureIndex::from_u32(sigindex))?;
     }
 
     Ok(())
@@ -139,7 +144,7 @@ pub fn parse_table_section(
     tables: TableSectionReader,
     environ: &mut dyn ModuleEnvironment,
 ) -> WasmResult<()> {
-    environ.reserve_tables(tables.get_count());
+    environ.reserve_tables(tables.get_count())?;
 
     for entry in tables {
         let table = entry?;
@@ -150,7 +155,7 @@ pub fn parse_table_section(
             },
             minimum: table.limits.initial,
             maximum: table.limits.maximum,
-        });
+        })?;
     }
 
     Ok(())
@@ -161,7 +166,7 @@ pub fn parse_memory_section(
     memories: MemorySectionReader,
     environ: &mut dyn ModuleEnvironment,
 ) -> WasmResult<()> {
-    environ.reserve_memories(memories.get_count());
+    environ.reserve_memories(memories.get_count())?;
 
     for entry in memories {
         let memory = entry?;
@@ -169,7 +174,7 @@ pub fn parse_memory_section(
             minimum: memory.limits.initial,
             maximum: memory.limits.maximum,
             shared: memory.shared,
-        });
+        })?;
     }
 
     Ok(())
@@ -180,7 +185,7 @@ pub fn parse_global_section(
     globals: GlobalSectionReader,
     environ: &mut dyn ModuleEnvironment,
 ) -> WasmResult<()> {
-    environ.reserve_globals(globals.get_count());
+    environ.reserve_globals(globals.get_count())?;
 
     for entry in globals {
         let wasmparser::Global {
@@ -199,14 +204,16 @@ pub fn parse_global_section(
             Operator::GetGlobal { global_index } => {
                 GlobalInit::GetGlobal(GlobalIndex::from_u32(global_index))
             }
-            ref s => panic!("unsupported init expr in global section: {:?}", s),
+            ref s => {
+                wasm_unsupported!("unsupported init expr in global section: {:?}", s);
+            }
         };
         let global = Global {
             ty: type_to_type(content_type).unwrap(),
             mutability: mutable,
             initializer,
         };
-        environ.declare_global(global);
+        environ.declare_global(global)?;
     }
 
     Ok(())
@@ -217,7 +224,7 @@ pub fn parse_export_section<'data>(
     exports: ExportSectionReader<'data>,
     environ: &mut dyn ModuleEnvironment<'data>,
 ) -> WasmResult<()> {
-    environ.reserve_exports(exports.get_count());
+    environ.reserve_exports(exports.get_count())?;
 
     for entry in exports {
         let Export {
@@ -231,20 +238,24 @@ pub fn parse_export_section<'data>(
         // becomes a concern here.
         let index = index as usize;
         match *kind {
-            ExternalKind::Function => environ.declare_func_export(FuncIndex::new(index), field),
-            ExternalKind::Table => environ.declare_table_export(TableIndex::new(index), field),
-            ExternalKind::Memory => environ.declare_memory_export(MemoryIndex::new(index), field),
-            ExternalKind::Global => environ.declare_global_export(GlobalIndex::new(index), field),
+            ExternalKind::Function => environ.declare_func_export(FuncIndex::new(index), field)?,
+            ExternalKind::Table => environ.declare_table_export(TableIndex::new(index), field)?,
+            ExternalKind::Memory => {
+                environ.declare_memory_export(MemoryIndex::new(index), field)?
+            }
+            ExternalKind::Global => {
+                environ.declare_global_export(GlobalIndex::new(index), field)?
+            }
         }
     }
 
-    environ.finish_exports();
+    environ.finish_exports()?;
     Ok(())
 }
 
 /// Parses the Start section of the wasm module.
 pub fn parse_start_section(index: u32, environ: &mut dyn ModuleEnvironment) -> WasmResult<()> {
-    environ.declare_start_func(FuncIndex::from_u32(index));
+    environ.declare_start_func(FuncIndex::from_u32(index))?;
     Ok(())
 }
 
@@ -253,7 +264,7 @@ pub fn parse_element_section<'data>(
     elements: ElementSectionReader<'data>,
     environ: &mut dyn ModuleEnvironment,
 ) -> WasmResult<()> {
-    environ.reserve_table_elements(elements.get_count());
+    environ.reserve_table_elements(elements.get_count())?;
 
     for entry in elements {
         let Element { kind, items } = entry?;
@@ -268,7 +279,9 @@ pub fn parse_element_section<'data>(
                 Operator::GetGlobal { global_index } => {
                     (Some(GlobalIndex::from_u32(global_index)), 0)
                 }
-                ref s => panic!("unsupported init expr in element section: {:?}", s),
+                ref s => {
+                    wasm_unsupported!("unsupported init expr in element section: {:?}", s);
+                }
             };
             let items_reader = items.get_items_reader()?;
             let mut elems = Vec::with_capacity(usize::try_from(items_reader.get_count()).unwrap());
@@ -281,9 +294,9 @@ pub fn parse_element_section<'data>(
                 base,
                 offset,
                 elems.into_boxed_slice(),
-            )
+            )?
         } else {
-            panic!("unsupported passive elements section");
+            wasm_unsupported!("unsupported passive elements section: {:?}", kind);
         }
     }
     Ok(())
@@ -308,7 +321,7 @@ pub fn parse_data_section<'data>(
     data: DataSectionReader<'data>,
     environ: &mut dyn ModuleEnvironment<'data>,
 ) -> WasmResult<()> {
-    environ.reserve_data_initializers(data.get_count());
+    environ.reserve_data_initializers(data.get_count())?;
 
     for entry in data {
         let Data { kind, data } = entry?;
@@ -323,16 +336,16 @@ pub fn parse_data_section<'data>(
                 Operator::GetGlobal { global_index } => {
                     (Some(GlobalIndex::from_u32(global_index)), 0)
                 }
-                ref s => panic!("unsupported init expr in data section: {:?}", s),
+                ref s => wasm_unsupported!("unsupported init expr in data section: {:?}", s),
             };
             environ.declare_data_initialization(
                 MemoryIndex::from_u32(memory_index),
                 base,
                 offset,
                 data,
-            );
+            )?;
         } else {
-            panic!("unsupported passive data section");
+            wasm_unsupported!("unsupported passive data section: {:?}", kind);
         }
     }
 
diff --git a/cranelift/wasm/src/translation_utils.rs b/cranelift/wasm/src/translation_utils.rs
index a41c70c4d9..90967d4102 100644
--- a/cranelift/wasm/src/translation_utils.rs
+++ b/cranelift/wasm/src/translation_utils.rs
@@ -1,5 +1,6 @@
 //! Helper functions and structures for the translation.
-use crate::environ::{WasmError, WasmResult};
+use crate::environ::WasmResult;
+use crate::wasm_unsupported;
 use core::u32;
 use cranelift_codegen::entity::entity_impl;
 use cranelift_codegen::ir;
@@ -119,7 +120,7 @@ pub fn type_to_type(ty: wasmparser::Type) -> WasmResult<ir::Type> {
         wasmparser::Type::I64 => ir::types::I64,
         wasmparser::Type::F32 => ir::types::F32,
         wasmparser::Type::F64 => ir::types::F64,
-        _ => return Err(WasmError::Unsupported("unsupported wasm type")),
+        ty => wasm_unsupported!("unsupported wasm type {:?}", ty),
     })
 }
 
@@ -132,7 +133,7 @@ pub fn tabletype_to_type(ty: wasmparser::Type) -> WasmResult<Option<ir::Type>> {
         wasmparser::Type::F32 => Some(ir::types::F32),
         wasmparser::Type::F64 => Some(ir::types::F64),
         wasmparser::Type::AnyFunc => None,
-        _ => return Err(WasmError::Unsupported("unsupported table wasm type")),
+        ty => wasm_unsupported!("unsupported table wasm type {:?}", ty),
     })
 }
 
@@ -141,7 +142,7 @@ pub fn blocktype_to_type(ty: wasmparser::TypeOrFuncType) -> WasmResult<ir::Type>
     match ty {
         wasmparser::TypeOrFuncType::Type(ty) => type_to_type(ty),
         wasmparser::TypeOrFuncType::FuncType(_) => {
-            Err(WasmError::Unsupported("multi-value block signatures"))
+            wasm_unsupported!("multi-value block signature {:?}", ty);
         }
     }
 }
@@ -165,10 +166,10 @@ pub fn num_return_values(ty: wasmparser::TypeOrFuncType) -> WasmResult<usize> {
             | wasmparser::Type::F32
             | wasmparser::Type::I64
             | wasmparser::Type::F64 => Ok(1),
-            _ => Err(WasmError::Unsupported("unsupported return value type")),
+            ty => wasm_unsupported!("unsupported return value type {:?}", ty),
         },
         wasmparser::TypeOrFuncType::FuncType(_) => {
-            Err(WasmError::Unsupported("multi-value block signatures"))
+            wasm_unsupported!("multi-value block signature {:?}", ty);
         }
     }
 }