[wasm] Slighly modify some error messages

This CL revises some of our error messages to be more precise or more
aesthetically appealing.

R=titzer@chromium.org, ahaas@chromium.org

Cq-Include-Trybots: luci.chromium.try:linux-blink-rel
Bug: chromium:926311
Change-Id: I38eaee09fd37f9b67fdb08bc7b0df64a6eaf96f9
Reviewed-on: https://chromium-review.googlesource.com/c/1445980Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59249}

src/wasm/module-decoder.cc

@@ -367,7 +367,7 @@ class ModuleDecoderImpl : public Decoder {
     // Check if the section is out-of-order.
     if (section_code < next_ordered_section_ &&
         section_code < kFirstUnorderedSection) {
-      errorf(pc(), "unexpected section: %s", SectionName(section_code));
+      errorf(pc(), "unexpected section <%s>", SectionName(section_code));
       return;
     }
 
@@ -446,18 +446,18 @@ class ModuleDecoderImpl : public Decoder {
         if (enabled_features_.bulk_memory) {
           DecodeDataCountSection();
         } else {
-          errorf(pc(), "unexpected section: %s", SectionName(section_code));
+          errorf(pc(), "unexpected section <%s>", SectionName(section_code));
         }
         break;
       case kExceptionSectionCode:
         if (enabled_features_.eh) {
           DecodeExceptionSection();
         } else {
-          errorf(pc(), "unexpected section: %s", SectionName(section_code));
+          errorf(pc(), "unexpected section <%s>", SectionName(section_code));
         }
         break;
       default:
-        errorf(pc(), "unexpected section: %s", SectionName(section_code));
+        errorf(pc(), "unexpected section <%s>", SectionName(section_code));
         return;
     }
 
@@ -680,7 +680,8 @@ class ModuleDecoderImpl : public Decoder {
       switch (exp->kind) {
         case kExternalFunction: {
           WasmFunction* func = nullptr;
-          exp->index = consume_func_index(module_.get(), &func);
+          exp->index =
+              consume_func_index(module_.get(), &func, "export function index");
           module_->num_exported_functions++;
           if (func) func->exported = true;
           break;
@@ -757,7 +758,8 @@ class ModuleDecoderImpl : public Decoder {
   void DecodeStartSection() {
     WasmFunction* func;
     const byte* pos = pc_;
-    module_->start_function_index = consume_func_index(module_.get(), &func);
+    module_->start_function_index =
+        consume_func_index(module_.get(), &func, "start function index");
     if (func &&
         (func->sig->parameter_count() > 0 || func->sig->return_count() > 0)) {
       error(pos, "invalid start function: non-zero parameter or return count");
@@ -804,7 +806,8 @@ class ModuleDecoderImpl : public Decoder {
       WasmElemSegment* init = &module_->elem_segments.back();
       for (uint32_t j = 0; j < num_elem; j++) {
         WasmFunction* func = nullptr;
-        uint32_t index = consume_func_index(module_.get(), &func);
+        uint32_t index =
+            consume_func_index(module_.get(), &func, "element function index");
         DCHECK_IMPLIES(ok(), func != nullptr);
         if (!ok()) break;
         DCHECK_EQ(index, func->func_index);
@@ -1267,8 +1270,9 @@ class ModuleDecoderImpl : public Decoder {
     return count;
   }
 
-  uint32_t consume_func_index(WasmModule* module, WasmFunction** func) {
-    return consume_index("function index", module->functions, func);
+  uint32_t consume_func_index(WasmModule* module, WasmFunction** func,
+                              const char* name) {
+    return consume_index(name, module->functions, func);
   }
 
   uint32_t consume_global_index(WasmModule* module, WasmGlobal** global) {

src/wasm/streaming-decoder.cc

@@ -486,7 +486,7 @@ StreamingDecoder::SectionBuffer* StreamingDecoder::CreateNewBuffer(
   // Check the order of sections. Unknown sections can appear at any position.
   if (section_id != kUnknownSectionCode) {
     if (section_id < next_section_id_) {
-      Error("Unexpected section");
+      Error("unexpected section");
       return nullptr;
     }
     next_section_id_ = section_id + 1;

test/mjsunit/wasm/start-function.js

@@ -46,7 +46,7 @@ assertThrows(() => {instantiate(kSig_i_v, [kExprI32Const, 0]);});
   assertThrows(
       () => builder.instantiate(), WebAssembly.CompileError,
       'WebAssembly.Module(): Wasm decoding failed: ' +
-          'function index 1 out of bounds (1 entry) @+20');
+          'start function index 1 out of bounds (1 entry) @+20');
 })();
 
 
@@ -63,7 +63,7 @@ assertThrows(() => {instantiate(kSig_i_v, [kExprI32Const, 0]);});
   assertThrows(
       () => builder.instantiate(), WebAssembly.CompileError,
       'WebAssembly.Module(): Wasm decoding failed: ' +
-          'unexpected section: Start @+27');
+          'unexpected section <Start> @+27');
 })();
 
 

test/unittests/wasm/module-decoder-unittest.cc

@@ -584,7 +584,7 @@ TEST_F(WasmModuleVerifyTest, ExceptionSectionBeforeGlobal) {
 
   WASM_FEATURE_SCOPE(eh);
   ModuleResult result = DecodeModule(data, data + sizeof(data));
-  EXPECT_NOT_OK(result, "unexpected section: Global");
+  EXPECT_NOT_OK(result, "unexpected section <Global>");
 }
 
 TEST_F(WasmModuleVerifyTest, ExceptionSectionAfterMemoryBeforeGlobal) {
@@ -596,7 +596,7 @@ TEST_F(WasmModuleVerifyTest, ExceptionSectionAfterMemoryBeforeGlobal) {
 
   WASM_FEATURE_SCOPE(eh);
   ModuleResult result = DecodeModule(data, data + sizeof(data));
-  EXPECT_NOT_OK(result, "unexpected section: Global");
+  EXPECT_NOT_OK(result, "unexpected section <Global>");
 }
 
 TEST_F(WasmModuleVerifyTest, ExceptionImport) {
@@ -2291,7 +2291,7 @@ TEST_F(WasmModuleVerifyTest, DataCountSectionBeforeElement) {
                               SECTION(Element, ENTRY_COUNT(0))};
   WASM_FEATURE_SCOPE(bulk_memory);
   ModuleResult result = DecodeModule(data, data + sizeof(data));
-  EXPECT_NOT_OK(result, "unexpected section: Element");
+  EXPECT_NOT_OK(result, "unexpected section <Element>");
 }
 
 TEST_F(WasmModuleVerifyTest, DataCountSectionAfterStartBeforeElement) {
@@ -2309,7 +2309,7 @@ TEST_F(WasmModuleVerifyTest, DataCountSectionAfterStartBeforeElement) {
   };
   WASM_FEATURE_SCOPE(bulk_memory);
   ModuleResult result = DecodeModule(data, data + sizeof(data));
-  EXPECT_NOT_OK(result, "unexpected section: Element");
+  EXPECT_NOT_OK(result, "unexpected section <Element>");
 }
 
 TEST_F(WasmModuleVerifyTest, MultipleDataCountSections) {