[clang] [clang][analyzer] Support `fputs` in the StreamChecker (PR #73335)

[Balázs Kéri via cfe-commits]

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@@ -141,6 +141,24 @@ void error_fputc(void) {
   fputc('A', F); // expected-warning {{Stream might be already closed}}
 }
 
+void error_fputs(void) {
+  FILE *F = tmpfile();
+  if (!F)
+    return;
+  int Ret = fputs("XYZ", F);
+  if (Ret >= 0) {
+    clang_analyzer_eval(feof(F) || ferror(F)); // expected-warning {{FALSE}}
+    fputs("QWD", F);                           // no-warning
+  } else {
+    clang_analyzer_eval(Ret == EOF); // expected-warning {{TRUE}}
+    clang_analyzer_eval(ferror(F));  // expected-warning {{TRUE}}
+    clang_analyzer_eval(feof(F));    // expected-warning {{FALSE}}
+    fputs("QWD", F);                 // expected-warning {{might be 'indeterminate'}}
+  }
+  fclose(F);
+  fputs("ABC", F);                   // expected-warning {{Stream might be already closed}}
+}
+
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balazske wrote:

One type of test is missing, where the stream is in EOF state (`StreamTesterChecker_make_feof_stream(F)` can be used to get such a stream `F`) and a `fputc` or `fputs` is called. Then no error and no warning should be generated, and the state after the call should be non-error and non-EOF.

https://github.com/llvm/llvm-project/pull/73335