allow exporting an import (#1326)

Author: kripken

src/wasm/wasm-validator.cpp

@@ -926,16 +926,13 @@ static void validateExports(Module& module, ValidationInfo& info) {
   for (auto& exp : module.exports) {
     Name name = exp->value;
     if (exp->kind == ExternalKind::Function) {
-      bool found = false;
-      for (auto& func : module.functions) {
-        if (func->name == name) {
-          found = true;
-          break;
-        }
-      }
-      info.shouldBeTrue(found, name, "module function exports must be found");
+      Import* imp;
+      info.shouldBeTrue(module.getFunctionOrNull(name) ||
+                        ((imp = module.getImportOrNull(name)) && imp->kind == ExternalKind::Function), name, "module function exports must be found");
     } else if (exp->kind == ExternalKind::Global) {
-      info.shouldBeTrue(module.getGlobalOrNull(name), name, "module global exports must be found");
+      Import* imp;
+      info.shouldBeTrue(module.getGlobalOrNull(name) ||
+                        ((imp = module.getImportOrNull(name)) && imp->kind == ExternalKind::Global), name, "module global exports must be found");
     } else if (exp->kind == ExternalKind::Table) {
       info.shouldBeTrue(name == Name("0") || name == module.table.name, name, "module table exports must be found");
     } else if (exp->kind == ExternalKind::Memory) {

test/export-import.wast

@@ -0,0 +1,8 @@
+(module
+ (type $v (func))
+ (import "env" "test1" (func $test1))
+ (import "env" "test2" (global $test2 i32))
+ (export "test1" (func $test1))
+ (export "test2" (global $test2))
+)
+

test/export-import.wast.from-wast

@@ -0,0 +1,9 @@
+(module
+ (type $v (func))
+ (type $FUNCSIG$v (func))
+ (import "env" "test1" (func $test1))
+ (import "env" "test2" (global $test2 i32))
+ (memory $0 0)
+ (export "test1" (func $test1))
+ (export "test2" (global $test2))
+)

test/export-import.wast.fromBinary

@@ -0,0 +1,10 @@
+(module
+ (type $0 (func))
+ (type $1 (func))
+ (import "env" "test2" (global $import$1 i32))
+ (import "env" "test1" (func $test1))
+ (memory $0 0)
+ (export "test1" (func $test1))
+ (export "test2" (global $import$1))
+)
+

test/export-import.wast.fromBinary.noDebugInfo

@@ -0,0 +1,10 @@
+(module
+ (type $0 (func))
+ (type $1 (func))
+ (import "env" "test2" (global $import$1 i32))
+ (import "env" "test1" (func $import$0))
+ (memory $0 0)
+ (export "test1" (func $import$0))
+ (export "test2" (global $import$1))
+)
+