jsifier: Add explicit error messages for missing/native alias targets

src/jsifier.js

@@ -350,6 +350,16 @@ function ${name}(${args}) {
             // Redirection for aliases. We include the parent, and at runtime make ourselves equal to it.
             // This avoid having duplicate functions with identical content.
             const redirectedTarget = snippet;
+            if (!(redirectedTarget in LibraryManager.library)) {
+              error(`${symbol}: alias target not found in JS library: ${redirectedTarget}`);
+            }
+            if (WASM_EXPORTS.has(redirectedTarget)) {
+              // JS symbols cannot currently alias native symbols, because
+              // the JS symbols are declared earlier in the output file.
+              // e.g. we cannot output `foo = _bar;` if `_bar` is native symbol
+              // otherwise closure compilains of JSC_REFERENCE_BEFORE_DECLARE.
+              error(`${symbol}: alias target cannot be a native symbol: ${redirectedTarget}`);
+            }
             deps.push(redirectedTarget);
             snippet = mangleCSymbolName(redirectedTarget);
           }

src/parseTools.js

@@ -838,7 +838,7 @@ function hasExportedSymbol(sym) {
 // it is a BigInt. Otherwise, we legalize into pairs of i32s.
 function defineI64Param(name) {
   if (WASM_BIGINT) {
-    return `/** @type {!BigInt} */ ${name}`;
+    return name;
   }
   return `${name}_low, ${name}_high`;
 }

system/lib/gl/webgl2.c

@@ -131,8 +131,6 @@ ASYNC_GL_FUNCTION_5(EM_FUNC_SIG_VIIIII, void, glTexStorage2D, GLenum, GLsizei, G
 ASYNC_GL_FUNCTION_6(EM_FUNC_SIG_VIIIIII, void, glTexStorage3D, GLenum, GLsizei, GLenum, GLsizei, GLsizei, GLsizei);
 VOID_SYNC_GL_FUNCTION_5(EM_FUNC_SIG_VIIIII, void, glGetInternalformativ, GLenum, GLenum, GLenum, GLsizei, GLint *);
 
-#endif // ~__EMSCRIPTEN_PTHREADS__
-
 // Extensions:
 GL_APICALL void GL_APIENTRY glVertexAttribDivisorNV(GLuint index, GLuint divisor) { glVertexAttribDivisor(index, divisor); }
 GL_APICALL void GL_APIENTRY glVertexAttribDivisorEXT(GLuint index, GLuint divisor) { glVertexAttribDivisor(index, divisor); }
@@ -153,6 +151,8 @@ GL_APICALL GLboolean GL_APIENTRY glIsVertexArrayOES(GLuint array) { return glIsV
 GL_APICALL void GL_APIENTRY glDrawBuffersEXT(GLsizei n, const GLenum *bufs) { glDrawBuffers(n, bufs); }
 GL_APICALL void GL_APIENTRY glDrawBuffersWEBGL(GLsizei n, const GLenum *bufs) { glDrawBuffers(n, bufs); }
 
+#endif // ~__EMSCRIPTEN_PTHREADS__
+
 // Returns a function pointer to the given WebGL 2 extension function, when queried without
 // a GL extension suffix such as "EXT", "OES", or "ANGLE". This function is used by
 // emscripten_GetProcAddress() to implement legacy GL emulation semantics for portability.

system/lib/gl/webgl_internal.h

@@ -7,6 +7,8 @@ EMSCRIPTEN_RESULT emscripten_webgl_do_commit_frame(void);
 EM_BOOL emscripten_supports_offscreencanvas(void);
 void _emscripten_proxied_gl_context_activated_from_main_browser_thread(EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context);
 
+#if defined(__EMSCRIPTEN_PTHREADS__) && defined(__EMSCRIPTEN_OFFSCREEN_FRAMEBUFFER__)
+
 #ifdef EMSCRIPTEN_WEBGL_TRACE
 #define GL_FUNCTION_TRACE(func) printf(#func "\n")
 #else
@@ -52,8 +54,6 @@ void _emscripten_proxied_gl_context_activated_from_main_browser_thread(EMSCRIPTE
 #define VOID_SYNC_GL_FUNCTION_10(sig, ret, functionName, t0, t1, t2, t3, t4, t5, t6, t7, t8, t9) ret functionName(t0 p0, t1 p1, t2 p2, t3 p3, t4 p4, t5 p5, t6 p6, t7 p7, t8 p8, t9 p9) { GL_FUNCTION_TRACE(functionName); if (pthread_getspecific(currentThreadOwnsItsWebGLContext)) emscripten_##functionName(p0, p1, p2, p3, p4, p5, p6, p7, p8, p9); else emscripten_sync_run_in_main_runtime_thread(sig, &emscripten_##functionName, p0, p1, p2, p3, p4, p5, p6, p7, p8, p9); }
 #define VOID_SYNC_GL_FUNCTION_11(sig, ret, functionName, t0, t1, t2, t3, t4, t5, t6, t7, t8, t9, t10) ret functionName(t0 p0, t1 p1, t2 p2, t3 p3, t4 p4, t5 p5, t6 p6, t7 p7, t8 p8, t9 p9, t10 p10) { GL_FUNCTION_TRACE(functionName); if (pthread_getspecific(currentThreadOwnsItsWebGLContext)) emscripten_##functionName(p0, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10); else emscripten_sync_run_in_main_runtime_thread(sig, &emscripten_##functionName, p0, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10); }
 
-#if defined(__EMSCRIPTEN_PTHREADS__) && defined(__EMSCRIPTEN_OFFSCREEN_FRAMEBUFFER__)
-
 #include <pthread.h>
 
 extern pthread_key_t currentActiveWebGLContext;

test/test_other.py

@@ -8656,6 +8656,7 @@ def test_closure_full_js_library(self, args):
       '-sFETCH',
       '-sFETCH_SUPPORT_INDEXEDDB',
       '-sLEGACY_GL_EMULATION',
+      '-sMAX_WEBGL_VERSION=2',
     ] + args)
 
   def test_closure_webgpu(self):