[clang] [clang][Modules] Diagnosing Module Redefinition Across ModuleMaps (PR #190085)

[Qiongsi Wu via cfe-commits]

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+// Test duplicating module decls discovered during by-name module scanning with
+// a shared compiler instance.
+// This tests covers the case where the current modulemap we are loading
+// contains a module decl that satisfies two conditions:
+// 1. The compiler has seen the module decl during previous lookups.
+// 2. The previous decl comes from a different modulemap.
+// In this case, an error is produced with no dependency information returned.
+
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: sed "s|DIR|%/t|g" %t/cdb.json.template > %t/cdb.json
+
+// Scenario setup:
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qiongsiwu wrote:

Done! 

https://github.com/llvm/llvm-project/pull/190085