[clang] [clang] Expand invalid PCM diagnostic (PR #69489)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Nuri Amari (NuriAmari)

<details>
<summary>Changes</summary>

Summary:

When a PCM file is loaded, it can go wrong in various ways. The current diagnostic only produces the name of the malformed PCM, not why it is malformed. Expand the diagnostic to display what went wrong!

There is only one call site for this diagnostic, and it already passes the error message:

https://github.com/llvm/llvm-project/blob/main/clang/lib/Serialization/ASTReader.cpp#L4763-L4764

Test Plan:

The modified LIT test.

---
Full diff: https://github.com/llvm/llvm-project/pull/69489.diff


2 Files Affected:

- (modified) clang/include/clang/Basic/DiagnosticSerializationKinds.td (+1-1) 
- (modified) clang/test/Modules/explicit-build.cpp (+1-1) 


``````````diff
diff --git a/clang/include/clang/Basic/DiagnosticSerializationKinds.td b/clang/include/clang/Basic/DiagnosticSerializationKinds.td
index a1ae23a62802104..1c049792d16eda4 100644
--- a/clang/include/clang/Basic/DiagnosticSerializationKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSerializationKinds.td
@@ -62,7 +62,7 @@ def err_ast_file_out_of_date : Error<
   "%select{PCH|module|AST}0 file '%1' is out of date and "
   "needs to be rebuilt%select{|: %3}2">, DefaultFatal;
 def err_ast_file_invalid : Error<
-  "file '%1' is not a valid precompiled %select{PCH|module|AST}0 file">, DefaultFatal;
+  "file '%1' is not a valid precompiled %select{PCH|module|AST}0 file: '%2'">, DefaultFatal;
 def note_module_file_imported_by : Note<
   "imported by %select{|module '%2' in }1'%0'">;
 def err_module_file_not_module : Error<
diff --git a/clang/test/Modules/explicit-build.cpp b/clang/test/Modules/explicit-build.cpp
index 16eb604708c9d83..42444369dc92c5f 100644
--- a/clang/test/Modules/explicit-build.cpp
+++ b/clang/test/Modules/explicit-build.cpp
@@ -161,7 +161,7 @@
 // RUN:            -fmodule-file=%t/not.pcm \
 // RUN:            %s 2>&1 | FileCheck --check-prefix=CHECK-BAD-FILE %s
 //
-// CHECK-BAD-FILE: fatal error: file '{{.*}}not.pcm' is not a valid precompiled module file
+// CHECK-BAD-FILE: fatal error: file '{{.*}}not.pcm' is not a valid precompiled module file: 'file too small to contain AST file magic'
 
 // RUN: not %clang_cc1 -x c++ -std=c++11 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -Rmodule-build -fno-modules-error-recovery \
 // RUN:            -fmodule-file=%t/nonexistent.pcm \

``````````

</details>


https://github.com/llvm/llvm-project/pull/69489