[clang] [serialization] No transitive type change (PR #92511)

[Ilya Biryukov via cfe-commits]

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@@ -0,0 +1,68 @@
+// Testing that changing a type in an unused module file won't change 
+// the BMI of the current module file.
+//
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -std=c++20 %t/m-partA.cppm -emit-reduced-module-interface -o %t/m-partA.pcm
+// RUN: %clang_cc1 -std=c++20 %t/m-partA.v1.cppm -emit-reduced-module-interface -o \
+// RUN:     %t/m-partA.v1.pcm
+// RUN: %clang_cc1 -std=c++20 %t/m-partB.cppm -emit-reduced-module-interface -o %t/m-partB.pcm
+// RUN: %clang_cc1 -std=c++20 %t/m.cppm -emit-reduced-module-interface -o %t/m.pcm \
+// RUN:     -fmodule-file=m:partA=%t/m-partA.pcm -fmodule-file=m:partB=%t/m-partB.pcm
+// RUN: %clang_cc1 -std=c++20 %t/m.cppm -emit-reduced-module-interface -o %t/m.v1.pcm \
+// RUN:     -fmodule-file=m:partA=%t/m-partA.v1.pcm -fmodule-file=m:partB=%t/m-partB.pcm
+//
+// RUN: %clang_cc1 -std=c++20 %t/useBOnly.cppm -emit-reduced-module-interface -o %t/useBOnly.pcm \
+// RUN:     -fmodule-file=m=%t/m.pcm -fmodule-file=m:partA=%t/m-partA.pcm \
+// RUN:     -fmodule-file=m:partB=%t/m-partB.pcm
+// RUN: %clang_cc1 -std=c++20 %t/useBOnly.cppm -emit-reduced-module-interface -o %t/useBOnly.v1.pcm \
+// RUN:     -fmodule-file=m=%t/m.v1.pcm -fmodule-file=m:partA=%t/m-partA.v1.pcm \
+// RUN:     -fmodule-file=m:partB=%t/m-partB.pcm
+// Since useBOnly only uses partB from module M, the change in partA shouldn't affect
+// useBOnly.
+// RUN: diff %t/useBOnly.pcm %t/useBOnly.v1.pcm &> /dev/null
+
+//--- m-partA.cppm
+export module m:partA;
+
+//--- m-partA.v1.cppm
+export module m:partA;
+
+namespace NS {
+    class A {
+        public:
+            int getValue() {
+                return 43;
+            }
+    };
+}
+
+//--- m-partB.cppm
+export module m:partB;
+
+export inline int getB() {
+    return 430;
+}
+
+//--- m.cppm
+export module m;
+export import :partA;
+export import :partB;
+
+//--- useBOnly.cppm
+export module useBOnly;
+import m;
+
+export inline int get() {
+    return getB();
+}
+
+//--- useAOnly.cppm
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ilya-biryukov wrote:

This does not seem to be used. Should we remove it?

https://github.com/llvm/llvm-project/pull/92511