[libc] Enable 'sscanf' on the GPU #100211

Summary:
We can enable the sscanf function on the GPU now. This required adding
the configs to the scanf list so that the GPU build didn't do float
conversions.

Author: jhuber6

libc/config/gpu/entrypoints.txt

@@ -186,6 +186,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.stdio.sprintf
     libc.src.stdio.vsnprintf
     libc.src.stdio.vsprintf
+    libc.src.stdio.sscanf
     libc.src.stdio.feof
     libc.src.stdio.ferror
     libc.src.stdio.fflush

libc/docs/gpu/support.rst

@@ -234,10 +234,11 @@ printf         |check|    |check|
 vprintf        |check|    |check|
 fprintf        |check|    |check|
 vfprintf       |check|    |check|
-sprintf        |check|    |check|
-snprintf       |check|    |check|
-vsprintf       |check|    |check|
-vsnprintf      |check|    |check|
+sprintf        |check|
+snprintf       |check|
+vsprintf       |check|
+vsnprintf      |check|
+sscanf         |check|
 putchar        |check|    |check|
 fclose         |check|    |check|
 fopen          |check|    |check|

libc/test/src/stdio/CMakeLists.txt

@@ -261,6 +261,13 @@ add_libc_test(
     ${use_system_file}
 )
 
+if(LIBC_CONF_SCANF_DISABLE_FLOAT)
+  list(APPEND sscanf_test_copts "-DLIBC_COPT_SCANF_DISABLE_FLOAT")
+endif()
+if(LIBC_CONF_SCANF_DISABLE_INDEX_MODE)
+  list(APPEND sscanf_test_copts "-DLIBC_COPT_SCANF_DISABLE_INDEX_MODE")
+endif()
+
 add_libc_test(
   sscanf_test
   SUITE
@@ -271,6 +278,8 @@ add_libc_test(
     libc.src.stdio.sscanf
   LINK_LIBRARIES
     LibcFPTestHelpers
+  COMPILE_OPTIONS
+    ${sscanf_test_copts}
 )
 
 add_libc_test(

libc/test/src/stdio/sscanf_test.cpp

@@ -226,6 +226,7 @@ TEST(LlvmLibcSScanfTest, IntConvNoWriteTests) {
   EXPECT_EQ(result, 0);
 }
 
+#ifndef LIBC_COPT_SCANF_DISABLE_FLOAT
 TEST(LlvmLibcSScanfTest, FloatConvSimple) {
   int ret_val;
   float result = 0;
@@ -580,7 +581,9 @@ TEST(LlvmLibcSScanfTest, FloatConvNoWrite) {
   ret_val = LIBC_NAMESPACE::sscanf("Not a float", "%*f", &result);
   EXPECT_EQ(ret_val, 0);
 }
+#endif
 
+#ifndef LIBC_COPT_SCANF_DISABLE_INDEX_MODE
 TEST(LlvmLibcSScanfTest, CurPosCombined) {
   int ret_val;
   int result = -1;
@@ -628,6 +631,7 @@ TEST(LlvmLibcSScanfTest, CurPosCombined) {
   EXPECT_EQ(ret_val, 1);
   EXPECT_EQ(result, 320);
 }
+#endif
 
 TEST(LlvmLibcSScanfTest, PointerConvCombined) {
   int ret_val;