[clang-tools-extra] [clang-doc] Remove uses of consumeError (PR #168759)

[Paul Kirth via cfe-commits]

https://github.com/ilovepi created https://github.com/llvm/llvm-project/pull/168759

In BitcodeReader, we were using consumeError(), which drops the error
and hides it from normal usage. To avoid that, we can just slightly
tweak the API to return an Expected<T>, and propagate the error
accordingly.

>From f6a508eb3266be28d4715856f2665a9f0db19946 Mon Sep 17 00:00:00 2001
From: Paul Kirth <paulkirth at google.com>
Date: Wed, 19 Nov 2025 11:00:51 -0800
Subject: [PATCH] [clang-doc] Remove uses of consumeError

In BitcodeReader, we were using consumeError(), which drops the error
and hides it from normal usage. To avoid that, we can just slightly
tweak the API to return an Expected<T>, and propagate the error
accordingly.
---
 clang-tools-extra/clang-doc/BitcodeReader.cpp | 46 ++++++++-----------
 clang-tools-extra/clang-doc/BitcodeReader.h   |  2 +-
 2 files changed, 21 insertions(+), 27 deletions(-)

diff --git a/clang-tools-extra/clang-doc/BitcodeReader.cpp b/clang-tools-extra/clang-doc/BitcodeReader.cpp
index 4efbbd34730cf..0af7aeb1d3500 100644
--- a/clang-tools-extra/clang-doc/BitcodeReader.cpp
+++ b/clang-tools-extra/clang-doc/BitcodeReader.cpp
@@ -847,9 +847,11 @@ llvm::Error ClangDocBitcodeReader::readBlock(unsigned ID, T I) {
 
   while (true) {
     unsigned BlockOrCode = 0;
-    Cursor Res = skipUntilRecordOrBlock(BlockOrCode);
+    llvm::Expected<Cursor> C = skipUntilRecordOrBlock(BlockOrCode);
+    if (!C)
+      return C.takeError();
 
-    switch (Res) {
+    switch (*C) {
     case Cursor::BadBlock:
       return llvm::createStringError(llvm::inconvertibleErrorCode(),
                                      "bad block found");
@@ -985,45 +987,39 @@ llvm::Error ClangDocBitcodeReader::readSubBlock(unsigned ID, T I) {
   }
 }
 
-ClangDocBitcodeReader::Cursor
+llvm::Expected<ClangDocBitcodeReader::Cursor>
 ClangDocBitcodeReader::skipUntilRecordOrBlock(unsigned &BlockOrRecordID) {
   llvm::TimeTraceScope("Reducing infos", "skipUntilRecordOrBlock");
   BlockOrRecordID = 0;
 
   while (!Stream.AtEndOfStream()) {
-    Expected<unsigned> MaybeCode = Stream.ReadCode();
-    if (!MaybeCode) {
-      // FIXME this drops the error on the floor.
-      consumeError(MaybeCode.takeError());
-      return Cursor::BadBlock;
-    }
+    Expected<unsigned> Code = Stream.ReadCode();
+    if (!Code)
+      return Code.takeError();
 
-    unsigned Code = MaybeCode.get();
-    if (Code >= static_cast<unsigned>(llvm::bitc::FIRST_APPLICATION_ABBREV)) {
+    if (*Code >= static_cast<unsigned>(llvm::bitc::FIRST_APPLICATION_ABBREV)) {
       BlockOrRecordID = Code;
       return Cursor::Record;
     }
-    switch (static_cast<llvm::bitc::FixedAbbrevIDs>(Code)) {
+    switch (static_cast<llvm::bitc::FixedAbbrevIDs>(*Code)) {
     case llvm::bitc::ENTER_SUBBLOCK:
       if (Expected<unsigned> MaybeID = Stream.ReadSubBlockID())
         BlockOrRecordID = MaybeID.get();
-      else {
-        // FIXME this drops the error on the floor.
-        consumeError(MaybeID.takeError());
-      }
+      else
+        return MaybeID.takeError();
       return Cursor::BlockBegin;
     case llvm::bitc::END_BLOCK:
       if (Stream.ReadBlockEnd())
-        return Cursor::BadBlock;
+        return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                       "error at end of block");
       return Cursor::BlockEnd;
     case llvm::bitc::DEFINE_ABBREV:
-      if (llvm::Error Err = Stream.ReadAbbrevRecord()) {
-        // FIXME this drops the error on the floor.
-        consumeError(std::move(Err));
-      }
+      if (llvm::Error Err = Stream.ReadAbbrevRecord())
+        return std::move(Err);
       continue;
     case llvm::bitc::UNABBREV_RECORD:
-      return Cursor::BadBlock;
+      return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                     "found unabbreviated record");
     case llvm::bitc::FIRST_APPLICATION_ABBREV:
       llvm_unreachable("Unexpected abbrev id.");
     }
@@ -1149,10 +1145,8 @@ ClangDocBitcodeReader::readBitcode() {
         return std::move(Err);
       continue;
     default:
-      if (llvm::Error Err = Stream.SkipBlock()) {
-        // FIXME this drops the error on the floor.
-        consumeError(std::move(Err));
-      }
+      if (llvm::Error Err = Stream.SkipBlock())
+        return std::move(Err);
       continue;
     }
   }
diff --git a/clang-tools-extra/clang-doc/BitcodeReader.h b/clang-tools-extra/clang-doc/BitcodeReader.h
index 4947721f0a06d..0f7f4f256f15b 100644
--- a/clang-tools-extra/clang-doc/BitcodeReader.h
+++ b/clang-tools-extra/clang-doc/BitcodeReader.h
@@ -59,7 +59,7 @@ class ClangDocBitcodeReader {
 
   // Helper function to step through blocks to find and dispatch the next record
   // or block to be read.
-  Cursor skipUntilRecordOrBlock(unsigned &BlockOrRecordID);
+  llvm::Expected<Cursor> skipUntilRecordOrBlock(unsigned &BlockOrRecordID);
 
   // Helper function to set up the appropriate type of Info.
   llvm::Expected<std::unique_ptr<Info>> readBlockToInfo(unsigned ID);