[llvm] [RISCV] Detect duplicate extensions in parseNormalizedArchString. (PR #91416)

[Craig Topper via llvm-commits]

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@@ -492,7 +492,9 @@ RISCVISAInfo::parseNormalizedArchString(StringRef Arch) {
                                "'" + Twine(ExtName[0]) +
                                    "' must be followed by a letter");
 
-    ISAInfo->addExtension(ExtName, {MajorVersion, MinorVersion});
+    if (!ISAInfo->addExtension(ExtName, {MajorVersion, MinorVersion}))
+      return createStringError(errc::invalid_argument,
+                               "duplicate extension '" + ExtName + "'");
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topperc wrote:

> Could we inform the user which version was ultimately chosen?

We don't chose a version, we fail the parsing.

https://github.com/llvm/llvm-project/pull/91416