Make check_symbols not accept dynamic c++ symbols

Turns out our static usearch library still depended on the cpp runtime
library libstdc++ dynamically.
This usually did not cause issues since postgres
commonly links libstdc++ dynamically so c++ symbols in our .so would be
resolved dynamically, when loaded.

This did cause issues for when postgres was not linked with libstdc++. I
do not know when exactly this happens but it seems this at least happens
when building postgres from source under certain circumstances

This commit makes sure that we do not use libstdc++ symbols from
postgres dynamic library dependency and actually enforce that all c++
symbols we require are in the sahred object we build

scripts/check_symbols.sh

@@ -6,7 +6,9 @@ SCRIPT=$(realpath "$0")
 THIS_DIR=$(dirname "$SCRIPT")
 
 # get all the symbols our shared library assumes are externally provided
-MAYBE_EXTERN=$(nm -D $1 | grep ' U ' | awk '{print $2}' | sed -e 's/@.*//')
+# libraries in extern_defined.sh use two @ symbols to separate symbol name from
+# version. the sed fixes the discrepancy between here and extern_defined.sh
+MAYBE_EXTERN=$(nm -D $1 | grep ' U ' | awk '{print $2}' | sed -e 's/@/@@/')
 
 # get all the symbols that are externally provided
 EXTERN_PROVIDED=$($THIS_DIR/extern_defined.sh)

scripts/extern_defined.sh

@@ -34,27 +34,50 @@ IFS=$'\n\t'
 # 3. use platorm specific equivalent of nm, ldd, awk
 
 PG_BIN=$(pg_config --bindir)/postgres
-
+SED_PATTERN='s/@/@/p' # noop pattern
 # " T " - text symbol
-nm -D  $PG_BIN | grep " T " | awk '{print $3}' | sed -e 's/@.*$//p'
+nm -D --with-symbol-versions $PG_BIN | grep " T " | awk '{print $3}' | sed -e "$SED_PATTERN"
 # global bss symbol in postgres
-nm -D  $PG_BIN | grep " B " | awk '{print $3}' | sed -e 's/@.*$//p'
+nm -D --with-symbol-versions $PG_BIN | grep " B " | awk '{print $3}' | sed -e "$SED_PATTERN"
 # postgres weak symbols
-nm -D  $PG_BIN | grep " w " | awk '{print $2}' | sed -e 's/@.*$//p'
+nm -D --with-symbol-versions $PG_BIN | grep " w " | awk '{print $2}' | sed -e "$SED_PATTERN"
 
 # Get a list of shared library dependencies using ldd
 dependencies=$(ldd "$PG_BIN" | awk '{print $3}' | grep -v "not a dynamic executable")
 
 # Loop through the dependencies and extract symbols
 for dependency in $dependencies; do
+   SED_PATTERN='s/@/@/p' # noop pattern
+   if grep -q "libstdc++" <<< "$dependency"; then
+      # even if postgres is linked against libstdc++, we should not use those and should
+      # always have our statically linked libstdc++ as postgres may not always be linked
+      # against libstdc++
+      continue
+   fi
+
+   if grep -q "libm" <<< "$dependency"; then
+      #libm does not use symbol versioning
+	   SED_PATTERN='s/@.*$//p'
+   fi
    # " U " - undefined symbol
-   nm -D "$dependency" | awk '/ U / {print $3}' | sed -e 's/@.*$//p'
+   nm -D --with-symbol-versions "$dependency" | awk '/ U / {print $3}' | sed -e "$SED_PATTERN"
    # " i " - the symbol is an indirect reference to another symbol. This is often used for compiler-generated code
-   nm -D "$dependency" | awk '/ i / {print $3}' | sed -e 's/@.*$//p'
+   nm -D --with-symbol-versions "$dependency" | awk '/ i / {print $3}' | sed -e "$SED_PATTERN"
    # " T " - The symbol is a text (code) symbol, representing a function or code that can be executed
-   nm -D "$dependency" | awk '/ T / {print $3}' | sed -e 's/@.*$//p'
+   nm -D --with-symbol-versions "$dependency" | awk '/ T / {print $3}' | sed -e "$SED_PATTERN"
    # " V " - the symbol is a weak object
-   nm -D "$dependency" | awk '/ V / {print $3}' | sed -e 's/@.*$//p'
+   nm -D --with-symbol-versions "$dependency" | awk '/ V / {print $3}' | sed -e "$SED_PATTERN"
    # " W " - the symbol is a weak symbol that has not been specifically tagged as weak object symbol
-   nm -D "$dependency" | awk '/ W / {print $3}' | sed -e 's/@.*$//p'
+   nm -D --with-symbol-versions "$dependency" | awk '/ W / {print $3}' | sed -e "$SED_PATTERN"
+   # " B " global bss symbol. e.g. __libc_single_threaded@@GLIBC_2.32
+   nm -D --with-symbol-versions "$dependency" | awk '/ B / {print $3}' | sed -e "$SED_PATTERN"
+   # " D " weak symbol. e.g. stderr@@GLIBC_2.2.5
+   nm -D --with-symbol-versions "$dependency" | awk '/ D / {print $3}' | sed -e "$SED_PATTERN"
 done
+
+# We link libstdc++ statically and it uses the symbol below from ld-linux
+# Now we need to add ld-linux symbols to extern_defined. Since this is the only symbol we use,
+# we can just filter and add only that one
+# " T " text symbol. e.g. __tls_get_addr
+LD_LINUX=$(ldd $(pg_config --bindir)/postgres| grep ld-linux | awk '{print $1}')
+nm -D --with-symbol-versions "$LD_LINUX" | awk '/ T / {print $3}' | sed -e "$SED_PATTERN" | grep __tls_get_addr