[COFF] Check errorCount before committing the output file

[mstorsjo]

Summary

This avoids producing an output file if errors appeared late in the linking process (e.g. while fixing relocations, or as in the test, while checking for multiple resources). If an output file is produced, build tools might not retry building it on rebuilds, even if a previous build failed due to the error return code.

[rnk]

lgtm

[ruiu]

LGTM

Thanks!

[thakis]

Thanks for doing this! :)

[thakis]

https://llvm.org/viewvc/llvm-project?view=revision&revision=369752 merged this to 9.0, since the dupe res obj file detection is new in 9.0.

COFF/Writer.cpp

void Writer::run() {
   if (!config->pdbPath.empty() && config->debug) {
     assert(buildId);
     createPDB(symtab, outputSections, sectionTable, buildId->buildId);
   }
   writeBuildId();
 
   writeMapFile(outputSections);
 
+  if (errorCount())
+    return;
+
   ScopedTimer t2(diskCommitTimer);
   if (auto e = buffer->commit())
     fatal("failed to write the output file: " + toString(std::move(e)));
 }
 
 static StringRef getOutputSectionName(StringRef name) {
   StringRef s = name.split('$').first;
 

test/COFF/multiple-resource-objs.test

 # RUN: llvm-cvtres /out:%t_resource.obj %S/Inputs/resource.res
 # RUN: llvm-cvtres /out:%t_id.obj %S/Inputs/id.res
+# RUN: rm -f %t.exe
 # RUN: not lld-link /out:%t.exe /dll /noentry %t_id.obj %t_resource.obj 2>&1 | \
 # RUN:     FileCheck --check-prefix=TWOOBJ %s
+# RUN: not test -f %t.exe
 
 TWOOBJ: error: {{.*}}_resource.obj: more than one resource obj file not allowed, already got {{.*}}_id.obj
 
 # RUN: not lld-link /out:%t.exe /dll /noentry %S/Inputs/id.res %t_resource.obj 2>&1 | \
 # RUN:     FileCheck --check-prefix=OBJRES %s
 
 OBJRES: error: internal .obj file created from .res files: more than one resource obj file not allowed, already got {{.*}}_resource.obj